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Femtosecond-multiphoton-ultrafast presentations at Photonics West 2009

Micromachining with Femtosecond Lasers
Date: Monday, 26 January 2009
Time: 1:30 PM – 5:30 PM

Author(s): Stefan Nolte, Friedrich-Schiller-Univ. Jena (Germany); Christopher B. Schaffer, Cornell Univ. (United States)


Femtosecond laser microstructuring of titanium surfaces for middle ear ossicular replacement prosthesis
Paper 7161C-304 of Conference 7161C
Date: Saturday, 24 January 2009
Time: 9:00 AM – 9:20 AM

Author(s): Justus F. R. Ilgner, Slavomir Biedron, Univ. Hospital Aachen (Germany); Elena Fadeeva, Boris N. Chichkov, Laser Zentrum Hannover e.V. (Germany); Martin Westhofen M.D., Univ. Hospital Aachen (Germany)

This study was performed to evaluate the effect of microstructures on titanium surfaces in contact with adjacent biological tissue. Titanium samples of 5mm diameter and 0,25mm thickness were structured by means of a Ti:Sapphire femtosecond laser with lines of parabolic shape (cross-sectional) of 5µm (parallel), 5µm (cross-hatch) and 10µm width (parallel). The inter-groove distance between two maxima was exactly twice the line width. Lines smaller than 5µm were not feasible due to the natural irregularity of the basic material with pits and level changes of up to 2µm.
The process showed little debris and constant microstructure shape over the whole structured area (2x2mm). Further studies will focus on chondrocyte growth on microstructured material.

Further progress in the development of the femtosecond-lentotomy treatment
Paper 7163-34 of Conference 7163
Date: Sunday, 25 January 2009
Time: 9:30 AM – 9:45 AM

Author(s): Silvia Schumacher, Michael Fromm, Laser Zentrum Hannover e.V. (Germany); Uwe Oberheide, Laserforum Köln (Germany); Patricia Bock, Ilka Imbschweiler, Univ. of Veterinary Medicine Hannover (Germany); Heike Hoffmann, Laser Zentrum Hannover e.V. (Germany); Georg Gerten, Laserforum Köln (Germany); Andreas Beineke, Univ. of Veterinary Medicine Hannover (Germany); Alfred R. Wegener, Univ. of Bonn (Germany); Holger Lubatschowski, Laser Zentrum Hannover e.V. (Germany)

One concept to treat presbyopia based on the Helmholtz theory of accommodation is the femtosecond-lentotomy. Femtosecond laser pulse induced micro incisions inside the crystalline lens create gliding planes which increase the flexibility of the hardened tissue.
Our aim was to evaluate the changes of the crystalline lens due to the fs-lentotomy treatment and its safety aspects. We used a 100 kHz repetition rate laser system to create microincisions in crystalline lenses of living rabbit eyes. The treated in vivo rabbit eyes were analysed using OCT and Scheimpflug imaging as well as histological sections up to three months postoperatively.

Femtosecond pulse shaping for single molecule measurements
Paper 7185-26 of Conference 7185
Date: Sunday, 25 January 2009
Time: 9:45 AM – 10:05 AM

Author(s): Fernando D. Stefani, Institut de Ciències Fotòniques (Spain) and Ludwig-Maximilians-Univ. München (Germany); Daan Brinks, Niek F. van Hulst, Institut de Ciències Fotòniques (Spain)

We developed a femtosecond pulse shaping scheme suitable for measurements at the nanoscale, therefore allowing new experiments on individual nano-systems and molecules. We demonstrate control over excitation probability of single molecules by shaping pulses on the femtosecond to picoseconds timescale. Unprecedented information about the ultrafast dynamics and spectral properties of the single molecules is obtained.

OCT-aided femtosecond laser micromachining device
Paper 7203-6 of Conference 7203
Date: Sunday, 25 January 2009
Time: 11:00 AM – 11:20 AM

Author(s): Ole Massow, Laser Zentrum Hannover e.V. (Germany); Fabian Will, Holger Lubatschowski, Rowiak GmbH (Germany)

Due to nonlinear interaction with biological tissue the femtosecond laser technology can be used for high precision micro machining. The resolution of a typical Optical Coherence Tomography system lies within the low µm range as well as the accuracy of the fs laser micro machining system. We demonstrate the setup and use of a system consisting of a fs-laser and a Fourier Domain OCT using the same high NA objective for both, cutting and imaging. Examples of in situ OCT images of the surgery area before and after treatment as well as OCT aided cuts in various biological tissue will be shown.

Multiphoton fluorescence microscopy using compact femtosecond fiber laser
Paper 7203-7 of Conference 7203
Date: Sunday, 25 January 2009
Time: 11:20 AM – 11:40 AM

Author(s): Cheryl Zhan, Chulmin Joo, Siavash Yazdanfar, GE Global Research (United States); Mikhail Berezin, Sam Achilefu, Washington Univ. in St. Louis School of Medicine (United States)

We developed a new MPM imaging system operating in the spectral window around 1550 nm, which features the optimal balance between scattering and absorption, and minimized the contribution of autofluorescence. This NIR window coincides with the primary telecommunications window, resulting in a plethora of available light sources including compact, turnkey femtosecond fiber lasers. The fluorescence emission is in the NIR wavelengths, which extends the penetration depth.

We synthesized new carbocyanine NIR fluorescent probes optimized at this particular window, and measured their two-photon fluorescence intensity and lifetime with time-correlated single photon counting.

Near-infrared femtosecond laser ablation of urinary calculi with submicron debris
Paper 7203-8 of Conference 7203
Date: Sunday, 25 January 2009
Time: 11:40 AM – 12:00 PM

Author(s): Jinze Qiu, The Univ. of Texas at Austin (United States); Joel M. Teichman, The Univ. of British Columbia (Canada); Roman V. Kuranov, Austin B. McElroy, Volcano Corp. (United States); Tianyi Wang, Amit S. Paranjape, Thomas E. Milner, The Univ. of Texas at Austin (United States)

Light emitted from a near infrared (800nm) femtosecond laser is capable of plasma induced ablation of various materials. We used a commercially available hollow core glass fiber to deliver femtosecond pulses and induced ablation on the surface of human urinary calculi. Femtosecond laser interaction with urinary calculi was investigated with various pulsed energy levels and number of applied pulses. Spectral-domain optical coherence tomography was used to image the cross sections of ablation craters on the surface of urinary calculi.

Femtosecond-laser nano-axotomy lab-on-a-chip for in-vivo nerve regeneration studies
Paper 7203-9 of Conference 7203
Date: Sunday, 25 January 2009
Time: 1:30 PM – 2:00 PM

Author(s): Samuel X. Guo, Frederic G. Bourgeois, The Univ. of Texas at Austin (United States); Trushal Chokshi, Univ. of Michigan (United States); Nicholas J. Durr, The Univ. of Texas at Austin (United States); Massimo Hilliard, The Univ. of Queensland (Australia); Nikos Chronis, Univ. of Michigan (United States); Adela Ben-Yakar, The Univ. of Texas at Austin (United States)

A thorough understanding of nerve regeneration in Caenorhabditis elegans requires performing femtosecond laser nanoaxotomy while minimally affecting the worm. We present a microfluidic device that fulfills such criteria and can easily be automated to enable high-throughput genetic and pharmacological screenings. We performed for the first time in-vivo nanoaxotomy and subsequent time-lapse imaging of regrowing axons in the absence of anesthetics, with the same precision and accuracy as previously achieved on agar pad with anesthetics. We discovered that axonal regeneration occurs much faster than previously described, and notably, the distal fragment of the severed axon regrows in the absence of anesthetics.

Probing cilia-driven flow in living embryos using femtosecond laser ablation and fast imaging
Paper 7203-10 of Conference 7203
Date: Sunday, 25 January 2009
Time: 2:00 PM – 2:30 PM

Author(s): Willy Supatto, Scott E. Fraser, Julien Vermot, California Institute of Technology (United States)

We devised an all-optical approach for probing microscopic fluid flows in vivo compatible with both normal biology and in vivo imaging. Sub-cellular femtosecond laser ablation deep inside an embryo was used to generate fluorescent micro-debris seeding the fluid. The seeded flow was subsequently imaged and quantified using fast confocal imaging and 3D-particle tracking. We illustrate this approach by investigating the flow generated within the zebrafish left-right organizer, a micrometer scale ciliated vesicle located deep inside the embryo and involved in breaking left-right embryonic symmetry. More generally, this all-optical strategy opens new opportunities for investigating microscopic flows in living tissues.

The femtosecond laser scalpel for proteomic and metabolomic mass spectrometry
Paper 7203-11 of Conference 7203
Date: Sunday, 25 January 2009
Time: 2:30 PM – 2:50 PM

Author(s): Christine L. Kalcic, Tissa C. Gunaratne, Gavin E. Reid, A. Daniel Jones, Marcos M. Dantus, Michigan State Univ. (United States)

In this presentation we will demonstrate how an amplified Ti:Al2O3 laser can be used as an excitation source for reproducible photodissociation MS/MS experiments of peptide cations. In particular, we will show how this approach, unlike CID, is able to cleave strong chemical bonds while leaving weaker bonds with high biological relevance intact. We will also present data for which spectral phase shaping is used to enhance ion activation using an adaptive pulse shaper. This work takes the first steps towards the realization of the “laser scalpel” – a tool that will allow mass spectrometrists to interrogate molecular structures with unprecedented precision using a single instrument.

Ablation of targeted neural processes in the zebrafish hindbrain using femtosecond laser pulses
Paper 7203-41 of Conference 7203
Date: Sunday, 25 January 2009
Time: 2:50 PM – 3:20 PM

Author(s): Jennifer Shum, Minoru Koyama, Francesca Minale, Nozomi Nishimura, Joseph Fetcho, Christopher B. Schaffer, Cornell Univ. (United States)

It remains difficult to study the causal link between neural circuitry and behavior. A common method is to lesion neurons and observe the behavioral consequences. However, interpreting effects after removing entire neurons poses some difficulties; killing a neuron removes a node from a highly interconnected network, abolishing all information flow into and out of the neuron. A more precise intervention would be to snip individual neural processes in the neural circuit, blocking information transmission at specific cut-points without killing cells.
This can be accomplished using femtosecond laser ablation as an in vivo light scalpel with submicrometer precision. Femtosecond laser ablation has been used to cut individual neural processes in the nematode worm, C. elegans. Here, we use femtosecond laser ablation to cut the lateral or ventral dendrite of the Mauthner (M) cell in zebrafish larvae, while leaving the cell alive and surrounding structures intact. The M cell is a neuron that triggers a fast start escape behavior, causing the fish to swim away from a threatening stimulus with reaction times of less than 10 ms. The lateral dendrite of this cell is thought to receive primarily tactile and auditory stimulus input, while the ventral dendrite receives primarily visual input. By studying changes in this escape behavior and in the cell electrphysiology in response to tactile and visual stimuli after cutting the lateral or ventral dendrite, we hope to determine the mechanisms by which this cell integrates stimulus information and triggers an escape response.
We determined that cutting the lateral or ventral dendrite of the M cell in 4 day old zebrafish larvae, while leaving the cell alive, is best achieved by irradiation with one laser pulse at an energy between 50 to 60 nJ, targeted at about three-quarters of the way along the dendrite, away from the cell body. The laser pulses were focused with a 0.95NA objective and generated from a Ti:Sapphire system operating at a 1-kHz repetition-rate with a 100-fs pulse duration. One pulse at this energy range gave a 50% success rate for cutting the dendrite, with about 10% showing no cell change and about 40% resulting in cell death. These fish were then evaluated using behavioral assays that determine the speed of the fast-start escape behavior in response to tactile stimulus as well as using whole-cell patch clamp electrophysiology to determine changes in response to both tactile and visual stimuli. Our initial results suggest a more complex role for the lateral dendrite in this neuronal circuit than that suggested by the anatomical connectivity.

Femtosecond laser writing of integrated Bragg-grating waveguides and microfluidic channels for optofluidic sensing
Paper 7203-12 of Conference 7203
Date: Monday, 26 January 2009
Time: 8:30 AM – 8:50 AM

Author(s): Jason R. Grenier, Valeria A. Maselli, Stephen Ho, Shicong Yang, Peter R. Herman, Univ. of Toronto (Canada)

Femtosecond laser writing was optimized in fused silica to integrate microfluidic channels and Bragg Grating Waveguides (BGWs) to form 3D optofluidic sensing microsystems. BGW devices were simultaneously formed in parallel lines with microfluidic channels to enable strong evanescent field penetration of the waveguide mode for refractive index characterization of the fluidic medium in the 1 to 1.442 range. BPM and FDTD waveguide modelling facilitated device design for enhancing refractive index response at 1550-nm wavelength, while S-bend waveguides with spectrally narrowed Bragg resonant responses were further engineered to improved device accuracy. 3D Optofluidic microsystems with reference gratings for temperature and strain compensation are presented as a new direction for optical sensing in biochips, chemical reactors, and general fluidic applications.

High-power multicrystal cw and femtosecond mode-locked oscillators based on Yb:KYW
Paper 7193-21 of Conference 7193
Date: Monday, 26 January 2009
Time: 8:30 AM – 8:50 AM

Author(s): Katrin S. Wentsch, Anne-Laure I. Calendron, Maximilian J. Lederer, High Q Laser Production GmbH (Austria)

We present results from diode-pumped cw and ultrashort pulse lasers using multiple bulk Yb:KYW crystals in a resonator optimised for this operation. From a dual-crystal resonator we obtain nearly 23W of cw-power in a diffraction limited beam and a maximum power of more than 24W limited by the available pump power. Mode-locked in the soliton regime using a semiconductor saturable absorber mirror (SESAM) we obtain more than 14.6W average power with a pulsewidth of 440fs at a repetition rate of 79MHz whilst the same oscillator delivered 15.3W in the positive dispersion regime with a similar pulsewidth.

The propagation properties of TW-femtosecond multiple laser pulses named "Azimuthons" in air
Paper 7200-2 of Conference 7200
Date: Monday, 26 January 2009
Time: 8:30 AM – 8:50 AM

Author(s): Xusheng Zhou, Jifeng Zu, Shanghai Institute of Optics and Fine Mechanics (China)

In this paper, we introduced the concept of Optical Vortex (OV) to control the filament. The propagation properties of a TW femtosecond laser multi pulses named “Azimuthons” are numerically demonstrated via the (2D+1) model for the first time. By changing some factors of the pulses, such as the distance and phase difference among the pulses, etc., the distances and stability of the propagation of the pulses in air are discussed. By using some kinds of step-phase plates (SPPs) to segement spatially the phase of the input laser pulse, the pulse behaving like a vortex is found, and at last, some comparisons between the single pulse with the SPP and the “Azimuthons” are also given.

Nanostructure formation processes in femtosecond laser ablation of thin film surfaces
Paper 7201-1 of Conference 7201
Date: Monday, 26 January 2009
Time: 8:40 AM – 9:20 AM

Author(s): Godai Miyaji, Kenzo Miyazaki, Kyoto Univ. (Japan)

We have studied the origin of periodic nanostructure formation on thin film surfaces in femtosecond laser ablation at low fluence. Using diamondlike carbon films patterned with submicrometer-size stripes, we have observed that the nanoscale ablation is preferentially initiated by a local electric field enhanced on the stripe surface with high curvature. The experimental results for the initial stage of nanostructuring show that the nanoscale ablation can be developed with the periodic enhancement of local fields through the excitation of surface plasmon polaritons in the surface layer. The estimated field periodicity is in good agreement with the observed size of nanostructures.

Femtosecond laser direct written diffractive optical elements and their integration in oxide glass
Paper 7203-13 of Conference 7203
Date: Monday, 26 January 2009
Time: 8:50 AM – 9:10 AM

Author(s): Jiyeon Choi, Martin C. Richardson, College of Optics & Photonics/Univ. of Central Florida (United States)

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Femtosecond laser direct writing is a unique technique to produce volumetric structural modification with high spatial resolution in a transparent medium. Hence it is suitable to generate not only periodical structures but also non-periodically distributed refractive index change in glass such as volumetric Diffractive Optical Elements (DOEs). We investigate the fabrication and characterization of photo-written Fresnel Zone Plates (FZPs) by using various femtosecond lasers. Diffraction Efficiency (DE) is investigated as functions of laser and writing parameters. Integration of more than two FZPs to improve diffraction efficiency and to modify beam distribution is described as well.

Integrating optics and micro-fluidic channels using femtosecond laser irradiation
Paper 7203-15 of Conference 7203
Date: Monday, 26 January 2009
Time: 9:30 AM – 10:00 AM

Author(s): Troy P. Anderson, M. Ramme, College of Optics & Photonics/Univ. of Central Florida (United States); Nathan Carlie, Clemson Univ. (United States); Jiyeon Choi, C. Faris, College of Optics & Photonics/Univ. of Central Florida (United States); Laeticia C. Petit, Kathleen Richardson, Clemson Univ. (United States); Martin C. Richardson, College of Optics & Photonics/Univ. of Central Florida (United States)

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The ability to integrate micro-channels for fluid transport with optical elements is attractive for the development of compact and portable chip-based sensors. Femtosecond Laser Direct Writing (FLDW) in transparent materials is a powerful fabrication technique for the fabrication of such integrated devices. We demonstrate the use of FLDW to fabricate coupled micro-fluidic channels and optical waveguides towards an integrated sensing device for molecular detection. Waveguides were directly written into the host material and channels were formed by modifying the molecular structure through FLDW followed by wet chemical etching. Multiple host materials including Chalcogenide glasses for IR detection are discussed.

Femtosecond laser written chirped fiber Bragg gratings
Paper 7203-18 of Conference 7203
Date: Monday, 26 January 2009
Time: 11:10 AM – 11:30 AM

Author(s): Christian Voigtländer, Jens U. Thomas, Elodie Wikszak, Stefan Nolte, Friedrich-Schiller-Univ. Jena (Germany); Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany) and Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)

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Fiber Bragg gratings (FBGs) are key components in optical communication systems. In recent years they have also become important as cavity mirrors for laser systems. Chirped fiber Bragg gratings (CFBGs) are attractive for dispersion control and compensation.

Here we report on two different approaches to inscribe CFBGs in non photosensitive fibers by femtosecond laser pulses like bending the fiber in the interference pattern of a periodic phase mask. Another approach is based on a polymer phase mask with a high thermal expansion coefficient in order to tune the period by changing the temperature.

High-strength fused-silica flexures manufactured by femtosecond laser
Paper 7203-19 of Conference 7203
Date: Monday, 26 January 2009
Time: 11:30 AM – 11:50 AM

Author(s): Yves Bellouard, Eindhoven Univ. of Technology (Netherlands); Ali A. Said, Mark A. Dugan, Philippe Bado, Translume, Inc. (United States)

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Flexures are mechanical elements used in micro- and precision-engineering to precisely guide the motion of micro-parts. They consist of slender bodies that deform elastically upon the application of a force. Although counter-intuitive at first, fused silica is an attractive material for flexure. We report on high-aspect ratio fused silica flexures manufactured by femtosecond laser combined with chemical etching.

The manufactured elements show outstanding mechanical properties with flexural strengths largely exceeding those obtained with other technologies and materials. Fused silica flexures offer a mean to combine integrated optics with micro-mechanics in a single monolithic substrate.

Density modulation of transparent polymers by irradiation of femtosecond laser
Paper 7203-20 of Conference 7203
Date: Monday, 26 January 2009
Time: 11:50 AM – 12:10 PM

Author(s): Hiroyuki Mochizuki, Wataru Watanabe, National Institute of Advanced Industrial Science and Technology (Japan); Yasuyuki Ozeki, Kazuyoshi Itoh, Osaka Univ. (Japan); Katsumi Matsuda, Satoshi Hirono, Omron Corp. (Japan)

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Bragg-type gratings were prepared by femtosecond laser irradiation in a series of optical polymers. The diffraction efficiency of polymethylpentene (PMP) was an order of magnitude higher than those of other polymers. Repeated scanning irradiation with femtosecond laser light formed gratings by refractive index changes inside the polymers. In PMP, whose density was the lowest among the polymers examined, large volume contraction by femtosecond laser irradiation was observed with TEM. The larger refractive index change of PMP was attributed to its large volume contraction based on its low density.

Femtosecond-laser surface structuring of biocompatible metals
Paper 7203-21 of Conference 7203
Date: Monday, 26 January 2009
Time: 1:40 PM – 2:00 PM

Author(s): Anatoliy Y. Vorobyev, Chunlei Guo, Univ. of Rochester (United States)

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We perform femtosecond laser surface structuring of a number of metals for biomedical applications. The effects of laser fluence and the number of applied pulses on laser-induced surface topography are studied using scanning electron microscopy. We find that the femtosecond laser produces a large variety of nano-, micro-, and periodic-structures. Our results suggest that femtosecond laser treatment of metals produces a richer variety of surface structures that are beneficial for biomedical applications than long-pulse laser treatments.

Monitoring of microplasma formation and filamentation of tightly focused femtosecond laser pulses in dielectrics
Paper 7214-27 of Conference 7214
Date: Monday, 26 January 2009
Time: 1:48 PM – 2:16 PM

Author(s): Saulius Juodkazis, Vygantas Mizeikis, Hokkaido Univ. (Japan); Hiroaki Misawa, Hokkiado Univ. (Japan); Sergey I. Kudryashov, Vladimir D. Zvorykin, Andrei A. Ionin, P.N. Lebedev Physical Institute (Russian Federation)

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We report acoustic characterization of phenomena accompanying optical damage in solid dielectric crystals and glasses by tightly focused femtosecond laser pulses. Generation of the free-carrier plasma and filamentation of the laser pulse These phenomena are omnipresent in femtosecond laser microfabrication, which becomes increasingly popular tool for micro- and nano-structuring of optically transparent dielectrics. In our studies, contact acoustic monitoring technique was employed to perform spatially-resolved in situ detection of micro-plasma formation and filamentation of focused femtosecond laser pulses with supercritical powers in bulk dielectrics.

Soft x-ray source for nanostructure imaging using femtosecond-laser-irradiated clusters
Paper 7214-28 of Conference 7214
Date: Monday, 26 January 2009
Time: 2:16 PM – 2:44 PM

Author(s): Yuji Fukuda, Japan Atomic Energy Agency (Japan)

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The intense soft x-ray light source using the supersonic expansion of the mixed gas of helium and carbon dioxide,
when irradiated by a femtosecond Ti:sapphire laser pulse, is observed to enhance the radiation of soft x-rays from the carbon dioxide clusters. Using this soft x-ray emissions, nanostructure images of 100-nm-thick Mo foils in a wide field of view (square millimeter scale) with high spatial resolution (800 nm) are obtained with high dynamic range LiF crystal detectors. The local inhomogeneities of soft x-ray absorption by the nanometer-thick foils is measured with an accuracy of less than 3 %.

High performance multi-modal CARS microscopy using a single femtosecond source
Paper 7183-35 of Conference 7183
Date: Monday, 26 January 2009
Time: 2:20 PM – 2:35 PM

Author(s): Adrian F. Pegoraro, National Research Council Canada (Canada) and Queen's Univ. (Canada); Andrew Ridsdale, Douglas J. Moffatt, John P. Pezacki, National Research Council Canada (Canada); Albert Stolow, National Research Council Canada (Canada) and Queen's Univ. (Canada)

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We demonstrate high performance CARS microscopy using a simple fs Ti:Sapphire laser source combined with a photonic crystal fiber. Using optimally chirped fs pump and Stokes laser pulses, we achieve high quality multi-modal imaging (simultaneous CARS, two-photon fluorescence, and second harmonic generation) of live cells and tissues. Chirp as a control parameter permits simultaneous optimization of the spectral resolution and signal levels of these imaging modalities. We will show applications of our multi-modal CARS imaging technique to biomedical problems and discuss the optimization of these various microscopies for particular problems.

Ultrafast imaging of plasmas produced in conditions of femtosecond waveguide writing in dielectrics
Paper 7203-23 of Conference 7203
Date: Monday, 26 January 2009
Time: 2:20 PM – 2:40 PM

Author(s): Wojciech Gawelda, Daniel Puerto Garcia, Jan Siegel, Alejandro Ruiz de la Cruz, Andrés Ferrer Moreu, Marcial Galván Sosa, Francisco Javier Solís Céspedes, Consejo Superior de Investigaciones Cientificas (Spain)

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The filament by phase segmentation spatially for femtosecond laser pulses in air
Paper 7200-14 of Conference 7200
Date: Monday, 26 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Xusheng Zhou, Jifeng Zu, Shanghai Institute of Optics and Fine Mechanics (China)

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We numerically investigated multiple filamentation of a TW femtosecond laser pulse by phase segmentation spatially. Specific devices for this function could be random phase plates (RPPs) and step phase plates (SPPs), so the shapes of several cells for the phase segmentation spatially are designed. The simulation of the propagation of the laser pulses is realized via a reduced (2D+1) model. We found that the phase segmentation make the filaments split fast due to the un-absorptive boundary condition. The pulse could gain one-magnitude higher peak intensities than an identical free-propagation pulse. Also we noticed that there is the energy flow in the case of the SPP for the first time.

Two-beam interferometric inscription of UV-femtosecond fiber-Bragg gratings
Paper 7195-12 of Conference 7195
Date: Monday, 26 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Eric Lindner, Martin Becker, Sven Brückner, Joachim Bergmann, Manfred W. Rothhardt, Hartmut Bartelt, Institute of Photonic Technology (Germany)

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The inscription of fiber Bragg gratings with femtosecond laser radiation gives access to a wide range of new materials. The use of UV femtosecond laser radiation would give direct access to one-photon absorption in doped silica materials and could achieve gratings with high spatial resolution. Besides the choice of the inscription laser wavelength, also the inscription method is of importance. We have therefore investigated the use of an interferometric technique in combination with UV femtosecond laser pulses. The laser coherence has been considered and the wavelength tuning and reflection properties have been tested for several different types of fibers.

High-energy and high-power Yb:KGW femtosecond regenerative amplifier
Paper 7203-27 of Conference 7203
Date: Monday, 26 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Taisuke Miura, Shinji Ito, OMRON Laserfront Inc. (Japan)

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We are developing directly diode-pumped femtosecond lasers for industrial applications.
A mode-locked Yb:KYW laser with the pulse duration of 130fs has been developed as a seed laser. The Yb:KGW crystal in the regenerative amplifier is pumped by a 75-W fiber-coupled laser diode.

The 4-nJ seed pulse was amplified to 0.82mJ at the repetition rate of 1kHz. At the repetition rate of 100kHz, the averaged output achieved more than 3W after the pulse compression. Furthermore, the amplified pulse was compressed to nearly Fourier transform limit. The calculated transform limited pulse width and the measured pulse width was 319fs and 339fs, respectively.

Femtosecond fiber laser system for medical applications
Paper 7203-29 of Conference 7203
Date: Monday, 26 January 2009
Time: 4:50 PM – 5:10 PM

Author(s): Clemens Hönninger, JT Optical Engine GmbH & Co. KG (Germany); Marco Plötner, Bülend Ortac, Roland Ackermann, Robert Kammel, Jens Limpert, Stefan Nolte, Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)

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We report on the realization of a femtosecond fiber laser system delivering 5-µJ, sub-400-fs pulses at pulse repetition rates higher than 200 kHz. The system is monolithically integrated from the oscillator to the last booster amplifier stage. The 25 MHz pulse train of the oscillator is temporally stretched in a fiber-based stretcher, down-counted to the desired pulse repetition rate by using a fiber-coupled acousto-optic modulator, and amplified by a pre-amplifier stage followed by a large mode area booster amplifier. A temporal pulse compression takes place in a grating-based bulk compressor. The system was applied for the treatment of presbyopia.

Atmospheric pressure femtosecond laser imaging mass spectrometry
Paper 7182-68 of Conference 7182
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Yves Coello, Tissa C. Gunaratne, Marcos M. Dantus, Michigan State Univ. (United States)

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We present a novel atmospheric pressure femtosecond laser imaging mass spectrometry system able to ionize and fragment molecules regardless of their size via direct multiphoton excitation, without the need for a sample matrix. Our uses amplified femtosecond laser pulses and is able to deliver transform-limited (TL) 30fs focused pulses to the sample thanks to a multiphoton intrapulse interference phase scan (MIIPS) pulse shaper that characterizes and corrects the spectral phase distortions of the pulses, ensuring efficient and reproducible ionization within the focal volume. Various samples including biological tissue have been imaged with 10 um resolution using this approach.

Femtosecond laser surgery on the anterior segment of the eye: laser parameters and tissue optics
Paper 7163-67 of Conference 7163
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Karsten Plamann, Valeria Nuzzo, Florent Deloison, Donald A. Peyrot, Florent Aptel, Caroline Crotti, Ecole Nationale Supérieure de Techniques Avancées (France); Laurent Arnaud, Benoît C. Forget, René Descartes Univ. (France); Michèle Savoldelli, Jean-Marc Legeais, Hôpital Hôtel Dieu (France)

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Both corneal transplant and glaucoma surgery by femtosecond lasers have to overcome the difficulty of maintaining a good beam quality while focussing into strongly scattering tissue. Our objective is to elucidate the optimal beam parameters and to provide optimised laser devices. We will present surgical experiments as well as total and direct transmission spectra on tissues of the anterior segment. The results will be compared to a microstructural analysis of the tissues and a mathematical study of the long and short range order within these tissues, combined with calculations linking the macroscopic optical properties to the tissular microstructure.

Nonequilibrium/metastable high-pressure phase quenching of condensed matters using femtosecond laser-driven shock compression
Paper 7203-17 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 8:00 AM – 8:30 AM

Author(s): Tomokazu Sano, Akio Hirose, Osaka Univ. (Japan)

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Strong shock wave is driven during femtosecond laser ablation of condensed matters as a recoil pressure, and propagates into the material. Rising the pressure and the temperature in the shock wave, the material transforms to its high-pressure phase. The high-pressure phase once induced remains in the solid as a nonequilibrium/metastable material after the pressure release depending on the materials and conditions. We have quenched some high-pressure phases of solid materials such as iron, carbon, and titanium using femtosecond laser-driven shock wave. We will introduce the properties of the femtosecond laser-driven shock wave, experimental results, and thermodynamic estimation of states such as the pressure and the temperature in the shock wave in the talk.

Nonequilibrium/metastable high-pressure phase quenching of condensed matters using femtosecond laser-driven shock compression
Paper 7201-17 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 8:00 AM – 8:30 AM

Author(s): Tomokazu Sano, Akio Hirose, Osaka Univ. (Japan)

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Strong shock wave is driven during femtosecond laser ablation of condensed matters as a recoil pressure, and propagates into the material. Rising the pressure and the temperature in the shock wave, the material transforms to its high-pressure phase. The high-pressure phase once induced remains in the solid as a nonequilibrium/metastable material after the pressure release depending on the materials and conditions. We have quenched some high-pressure phases of solid materials such as iron, carbon, and titanium using femtosecond laser-driven shock wave. We will introduce the properties of the femtosecond laser-driven shock wave, experimental results, and thermodynamic estimation of states such as the pressure and the temperature in the shock wave in the talk.

Dynamics of femtosecond laser-induced breakdowns in water
Paper 7203-19 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 8:50 AM – 9:10 AM

Author(s): Akihiro Takita, Yoshio Hayasaki, Utsunomiya Univ. (Japan)

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To investigate dynamics of laser-induced phenomena on parallel femtosecond laser processing is important for fast and precise processing. A pump-probe interference microscope was used to measure time variations of intensity and phase distribution of water around laser focus. When two femtosecond laser pulses were irradiated simultaneously, an addition of shock waves and reflection of a shock wave at a center bubble were observed. Refractive index variation of overlapping shock waves became twice as high as that of a single shock wave.

Dynamics of femtosecond laser-induced breakdowns in water
Paper 7201-19 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 8:50 AM – 9:10 AM

Author(s): Akihiro Takita, Yoshio Hayasaki, Utsunomiya Univ. (Japan)

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To investigate dynamics of laser-induced phenomena on parallel femtosecond laser processing is important for fast and precise processing. A pump-probe interference microscope was used to measure time variations of intensity and phase distribution of water around laser focus. When two femtosecond laser pulses were irradiated simultaneously, an addition of shock waves and reflection of a shock wave at a center bubble were observed. Refractive index variation of overlapping shock waves became twice as high as that of a single shock wave.

Femtosecond laser doping of silicon beyond the solubility limit
Paper 7203-20 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 9:10 AM – 9:30 AM

Author(s): Mark T. Winkler, Meng-Ju Sher, Eric D. Mazur, Harvard Univ. (United States)

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Using femtosecond laser irradiation, we dope silicon with sulfur to ~1% atomic; a level beyond the equilibrium solubility limit by several orders of magnitude. This nonequilibrium phase of silicon exhibits many intriguing optical properties, such as near-unity absorbtance over a broad wavelength range (250 - 2500 nm). Remarkable optoelectronic devices have already been fabricated using this laser-doping technique, such as photodetectors exhibiting large photoconductive gain as well as infrared response at wavelengths as long as 1500nm. We believe additional devices are possible, such as a silicon-based solar cell that absorbs the infrared portion of the solar spectrum, where almost 30% of the sun's energy resides, and which passes directly through conventional silicon cells.

Femtosecond laser doping of silicon beyond the solubility limit
Paper 7201-20 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 9:10 AM – 9:30 AM

Author(s): Mark T. Winkler, Meng-Ju Sher, Eric D. Mazur, Harvard Univ. (United States)

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Using femtosecond laser irradiation, we dope silicon with sulfur to ~1% atomic; a level beyond the equilibrium solubility limit by several orders of magnitude. This nonequilibrium phase of silicon exhibits many intriguing optical properties, such as near-unity absorbtance over a broad wavelength range (250 - 2500 nm). Remarkable optoelectronic devices have already been fabricated using this laser-doping technique, such as photodetectors exhibiting large photoconductive gain as well as infrared response at wavelengths as long as 1500nm. We believe additional devices are possible, such as a silicon-based solar cell that absorbs the infrared portion of the solar spectrum, where almost 30% of the sun's energy resides, and which passes directly through conventional silicon cells.

Linear micromirror array for broadband femtosecond pulse shaping in phase and amplitude
Paper 7208-3 of Conference 7208
Date: Tuesday, 27 January 2009
Time: 9:20 AM – 9:40 AM

Author(s): Stefan M. Weber, Univ. de Genève (Switzerland); Severin Waldis, Wilfried Noell, Univ. de Neuchâtel (Switzerland); Denis Kiselev, Jérôme Extermann, Luigi Bonacina, Jean-Pierre Wolf, Univ. de Genève (Switzerland); Nicolaas F. de Rooij, Univ. de Neuchâtel (Switzerland)

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We are developing an SOI-based MEMS micromirror array designed for optical, femtosecond laser pulse shaping applications. It is a bulk-micromachined device, allowing to retard or diminish certain laser frequencies in order to perform phase and amplitude modulation within a frequency band spanning the UV to the near-infrared. The individual mirrors are fixed on either side by springs with two degrees of freedom: out-of-plane motion for phase shift and rotational motion for binary amplitude modulation, realized using independent sets of vertical comb drives. The first applications will include femtosecond discrimination experiments on biomolecules.

Nano-hemi-shell arrays produced by femtosecond laser microprocessing for SERS applications
Paper 7203-21 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 9:30 AM – 9:50 AM

Author(s): Tetsuo Sakai, Keio Univ. (Japan); Eric D. Diebold, Kevin Vora, Harvard Univ. (United States); Yuji Nishizawa, Henry Nugroho, Minoru Obara, Keio Univ. (Japan); Eric D. Mazur, Harvard Univ. (United States)

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Nano-scale periodic structures produce a greatly enhanced near-field at the surface and therefore they are very promising for applications involving Surface Enhanced Raman Scattering (SERS). The ideal shape of the structure is a sphere, a rod, a needle or a hemi-shell. Nano hemi-shell structures obtained by evaporating a thin metal film on small dielectric particles, in particular, have attracted much attention. We fabricate isolated, clusters of two or three particles and hexagonally-arranged nano hemi-shells on a glass substrate. We perform Raman spectroscopy to investigate the optical properties of 2D nano hemi-shell arrays composed of small polystyrene particles coated with gold and measure the electric field distribution around the structure using femtosecond laser pulses.

Nano-hemi-shell arrays produced by femtosecond laser microprocessing for SERS applications
Paper 7201-21 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 9:30 AM – 9:50 AM

Author(s): Tetsuo Sakai, Keio Univ. (Japan); Eric D. Diebold, Kevin Vora, Harvard Univ. (United States); Yuji Nishizawa, Henry Nugroho, Minoru Obara, Keio Univ. (Japan); Eric D. Mazur, Harvard Univ. (United States)

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Nano-scale periodic structures produce a greatly enhanced near-field at the surface and therefore they are very promising for applications involving Surface Enhanced Raman Scattering (SERS). The ideal shape of the structure is a sphere, a rod, a needle or a hemi-shell. Nano hemi-shell structures obtained by evaporating a thin metal film on small dielectric particles, in particular, have attracted much attention. We fabricate isolated, clusters of two or three particles and hexagonally-arranged nano hemi-shells on a glass substrate. We perform Raman spectroscopy to investigate the optical properties of 2D nano hemi-shell arrays composed of small polystyrene particles coated with gold and measure the electric field distribution around the structure using femtosecond laser pulses.

Near-field nanostructure processing with femtosecond laser excitation: metallic versus dielectric particle
Paper 7203-22 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 9:50 AM – 10:10 AM

Author(s): Yuto Tanaka, Yuji Nishizawa, Tomoya Miyanishi, Keio Univ. (Japan); Nikolay N. Nedyalkov, Petar A. Atanasov, Keio Univ. (Japan) and Bulgarian Academy of Sciences (Bulgaria); Minoru Obara, Keio Univ. (Japan)

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In this paper we present experimental and theoretical results on the processing properties by the optical near field induced by gold nanoparticles and transparent dielectric particles excited by ultrashort laser pulse. We will compare nano-plasmonic processing with dielectric near-field processing.

Near-field nanostructure processing with femtosecond laser excitation: metallic versus dielectric particle
Paper 7201-22 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 9:50 AM – 10:10 AM

Author(s): Yuto Tanaka, Yuji Nishizawa, Tomoya Miyanishi, Keio Univ. (Japan); Nikolay N. Nedyalkov, Petar A. Atanasov, Keio Univ. (Japan) and Bulgarian Academy of Sciences (Bulgaria); Minoru Obara, Keio Univ. (Japan)

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In this paper we present experimental and theoretical results on the processing properties by the optical near field induced by gold nanoparticles and transparent dielectric particles excited by ultrashort laser pulse. We will compare nano-plasmonic processing with dielectric near-field processing.

Discrete optics in femtosecond-laser written waveguide arrays
Paper 7203-23 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 10:40 AM – 11:10 AM

Author(s): Alexander Szameit, Friedrich-Schiller-Univ. Jena (Germany)

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During the last years, a variety of concepts for imaging, all-optical routing and switching were presented, utilizing the so-called “discrete optical” light propagation in integrated optical waveguides. As a very promising approach for the realization of the required truly three-dimensional devices, the femtosecond waveguide direct-writing technique experiences growing interest. Such laser-written structures provide many prospects not only for sophisticated applications, but also for fundamental research. In particular the possibility to variably create precise arrays of waveguides allows for the experimental investigation of many discrete optical phenomena based on evanescent coupling between the individual lattice sites, which will be reviewed in this presentation.

Discrete optics in femtosecond-laser written waveguide arrays
Paper 7201-23 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 10:40 AM – 11:10 AM

Author(s): Alexander Szameit, Friedrich-Schiller-Univ. Jena (Germany)

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During the last years, a variety of concepts for imaging, all-optical routing and switching were presented, utilizing the so-called “discrete optical” light propagation in integrated optical waveguides. As a very promising approach for the realization of the required truly three-dimensional devices, the femtosecond waveguide direct-writing technique experiences growing interest. Such laser-written structures provide many prospects not only for sophisticated applications, but also for fundamental research. In particular the possibility to variably create precise arrays of waveguides allows for the experimental investigation of many discrete optical phenomena based on evanescent coupling between the individual lattice sites, which will be reviewed in this presentation.

Volumetric photonic structures fabricated with femtosecond lasers
Paper 7203-24 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 11:10 AM – 11:40 AM

Author(s): Timothy Gerke, Rafael Piestun, Univ. of Colorado at Boulder (United States)

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Ultrashort pulse lasers enable the fabrication of volumetric arrangements within homogeneous and heterogeneous dielectric materials. We report on the design and fabrication of novel functional structures that include computer-generated volume holograms and aperiodic photonic crystals.

Volumetric photonic structures fabricated with femtosecond lasers
Paper 7201-24 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 11:10 AM – 11:40 AM

Author(s): Timothy Gerke, Rafael Piestun, Univ. of Colorado at Boulder (United States)

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Ultrashort pulse lasers enable the fabrication of volumetric arrangements within homogeneous and heterogeneous dielectric materials. We report on the design and fabrication of novel functional structures that include computer-generated volume holograms and aperiodic photonic crystals.

Investigating new sources of femtosecond fiber lasers in multiphoton microscopy
Paper 7183-56 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 11:15 AM – 11:30 AM

Author(s): Shuo Tang, Univ. of British Columbia (Canada) and Univ. of California, Irvine (United States); Jian Liu, PolarOnyx, Inc. (United States); Zhongping Chen, Bruce J. Tromberg, Univ. of California, Irvine (United States)

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Femtosecond fiber lasers have emerged as a promising light source for MPM applications. The laser system is reliable, compact, low-cost, and portable because it uses mostly fiber connected components from telecommunications. We have implemented compact, all-fiber based femtosecond fiber lasers in multiphoton imaging at the wavelength bands of 1030 nm and 1560 nm. Intrinsic second-harmonic generation signal is excited from rat tail tendon and human skin samples. Two-photon excited fluorescence images are obtained from tissues stained with exogenous fluorophores. Our results show that the femtosecond fiber lasers have the great potential of applications in developing all-fiber based, portable multiphoton endoscopes.

Memory effects in femtosecond collective spin rotation in ferromagnetic semiconductors
Paper 7214-37 of Conference 7214
Date: Tuesday, 27 January 2009
Time: 11:28 AM – 11:56 AM

Author(s): Jigang Wang, Lawrence Berkeley National Lab. (United States)

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We present a femtosecond response in photoinduced collective magnetization rotation in the ferromagnetic
semiconductor GaMnAs, which allows for detection of a four-state magnetic memory at the femtosecond
time scale. The temporal profile of this cooperative magnetization rotation exhibits a
discontinuity that reveals two distinct temporal regimes, marked by the transition from a highly
non-equilibrium, carrier-mediated regime within the first 200 fs, to a thermal, lattice-heating picosecond
regime

Toward femtosecond laser micromachined opto-fluidic devices for detection and identification of algae
Paper 7201-34 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 2:10 PM – 2:40 PM

Author(s): Yves Bellouard, Vijay K. Pahilwani, Eindhoven Univ. of Technology (Netherlands); Thomas Rohrlack, Norwegian Institute for Water Research (Norway); Ali A. Said, Mark A. Dugan, Philippe Bado, Translume, Inc. (United States)

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We explore the prospects of a miniaturized fluid channel with an integrated waveguide as a rudimentary but compact tool for beads and biological cell (algae) detection, counting and to a certain extent, identification.

A curved optical waveguide is used to illuminate particles flowing inside a fluidic channel. The changes in the transmitted signal are monitored using a four-quadrant photo-detector. The relative quadrant signals give rise to distinct wavelets which can be processed to distinguish different families of cells. In addition, simple information like flow direction can be stated.

The channel and waveguide are fabricated out of a monolithic fused-silica substrate using femtosecond laser writing process combined with chemical etching.

This chip is a robust proof-of-concept and paves the way for a more elaborate femtosecond laser-based analytical opto-fluidic device having a network of waveguides which would for fluorescence or metrology.

Toward femtosecond laser micromachined opto-fluidic devices for detection and identification of algae
Paper 7203-34 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 2:10 PM – 2:40 PM

Author(s): Yves Bellouard, Vijay K. Pahilwani, Eindhoven Univ. of Technology (Netherlands); Thomas Rohrlack, Norwegian Institute for Water Research (Norway); Ali A. Said, Mark A. Dugan, Philippe Bado, Translume, Inc. (United States)

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We explore the prospects of a miniaturized fluid channel with an integrated waveguide as a rudimentary but compact tool for beads and biological cell (algae) detection, counting and to a certain extent, identification.

A curved optical waveguide is used to illuminate particles flowing inside a fluidic channel. The changes in the transmitted signal are monitored using a four-quadrant photo-detector. The relative quadrant signals give rise to distinct wavelets which can be processed to distinguish different families of cells. In addition, simple information like flow direction can be stated.

The channel and waveguide are fabricated out of a monolithic fused-silica substrate using femtosecond laser writing process combined with chemical etching.

This chip is a robust proof-of-concept and paves the way for a more elaborate femtosecond laser-based analytical opto-fluidic device having a network of waveguides which would for fluorescence or metrology.


Wavelength dependence of nanosecond and femtosecond optical breakdown in water
Paper 7175-36 of Conference 7175
Date: Tuesday, 27 January 2009
Time: 3:30 PM – 4:00 PM

Author(s): Norbert Linz, Sebastian Freidank, Univ. zu Lübeck (Germany); Hannes Vogelmann, Thomas Trickl, Forschungszentrum Karlsruhe (Germany); Cord L. Arnold, Laser Zentrum Hannover e.V. (Germany); Alfred Vogel, Univ. zu Lübeck (Germany)

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Local force detection of femtosecond laser-induced stress wave using atomic force microscope
Paper 7201-37 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 3:50 PM – 4:10 PM

Author(s): Yoichiroh Hosokawa, Nara Institute of Science and Technology (Japan); Kazunori Okano, Nara Institute of Science and Technology (Japan) and Tohoku Fukushi Univ. (Japan); Hiroshi M. Masuhara, Nara Institute of Science and Technology (Japan) and National Chiao Tung Univ. (Taiwan)

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When an intense femtosecond laser is focused on the cell culture medium, an impulsive stress wave is induced by the propagation of the shockwave and generation and collapse of the cavitation bubble. We have applied the impulsive force to individual separation and transportation of animal cell which adheres on extra cellular matrix. In this work, the time and spatial evaluation of the impulsive force was investigated by using atomic force microscope and considered with results of high-speed imaging.

Local force detection of femtosecond laser-induced stress wave using atomic force microscope
Paper 7203-37 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 3:50 PM – 4:10 PM

Author(s): Yoichiroh Hosokawa, Nara Institute of Science and Technology (Japan); Kazunori Okano, Nara Institute of Science and Technology (Japan) and Tohoku Fukushi Univ. (Japan); Hiroshi M. Masuhara, Nara Institute of Science and Technology (Japan) and National Chiao Tung Univ. (Taiwan)

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When an intense femtosecond laser is focused on the cell culture medium, an impulsive stress wave is induced by the propagation of the shockwave and generation and collapse of the cavitation bubble. We have applied the impulsive force to individual separation and transportation of animal cell which adheres on extra cellular matrix. In this work, the time and spatial evaluation of the impulsive force was investigated by using atomic force microscope and considered with results of high-speed imaging.

Ultrasound characterization of cavitation microbubbles produced by femtosecond laser pulses
Paper 7175-38 of Conference 7175
Date: Tuesday, 27 January 2009
Time: 4:00 PM – 4:20 PM

Author(s): Andrei B. Karpiouk, Salavat R. Aglyamov, Frederic G. Bourgeois, Adela Ben-Yakar, Stanislav Y. Emelianov, The Univ. of Texas at Austin (United States)

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The ultrasound-based technique to monitor cavitation microbubbles induced by nanosecond laser was evaluated to characterize the microbubbles produced in water by a 100-fs single laser pulses with energies of 40-200 nJ and a wavelength of 780 nm using an 63x-objective with NA of 1.4. Temporal characteristics of passive acoustic emission and pulse/echo probing detected by a 48 MHz single-element ultrasound transducer with fractional bandwidth of 60%, an f-number of 1.4, and a focal distance of 5.5 mm were used to assess the microbubble location and size. The results agreed with theoretical predictions indicating the ultrasound technique's applicability to quantitatively assess 10 to 30-micrometers microbubbles.

Optical coherence microscopy for nondestructive 3D imaging of femtosecond laser written structures
Paper 7201-39 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 4:30 PM – 4:50 PM

Author(s): Jiyeon Choi, Kye-Sung Lee, Supraja Murali, Troy P. Anderson, Jannick P. Rolland, Martin C. Richardson, College of Optics & Photonics/Univ. of Central Florida (United States)

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Optical Coherence Microscopy (OCM) has become a powerful nondestructive 3D imaging technique for its high lateral and depth resolution. We investigate the feasibility of a use of OCM as a diagnostic tool for femtosecond laser direct writing to evaluate the quality of photo-induced volumetric structures produced within a transparent substrate. 3D structures of either refractive index change or optical breakdown were formed with the size from 10 to 100 m in a fused silica. 3D images of photo-written structures were obtained with high S/N ratio since the substrate has transparent window at both writing and probe laser wavelength.

Optical coherence microscopy for nondestructive 3D imaging of femtosecond laser written structures
Paper 7203-39 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 4:30 PM – 4:50 PM

Author(s): Jiyeon Choi, Kye-Sung Lee, Supraja Murali, Troy P. Anderson, Jannick P. Rolland, Martin C. Richardson, College of Optics & Photonics/Univ. of Central Florida (United States)

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Optical Coherence Microscopy (OCM) has become a powerful nondestructive 3D imaging technique for its high lateral and depth resolution. We investigate the feasibility of a use of OCM as a diagnostic tool for femtosecond laser direct writing to evaluate the quality of photo-induced volumetric structures produced within a transparent substrate. 3D structures of either refractive index change or optical breakdown were formed with the size from 10 to 100 m in a fused silica. 3D images of photo-written structures were obtained with high S/N ratio since the substrate has transparent window at both writing and probe laser wavelength.

High-power, low-noise, all-fiber, femtosecond supercontinuum source
Paper 7195-35 of Conference 7195
Date: Tuesday, 27 January 2009
Time: 5:20 PM – 5:40 PM

Author(s): Jeffrey W. Nicholson, Jayesh C. Jasapara, Keisuke Tominaga, Clifford Headley III, OFS Labs. (United States)

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We present an all-fiber femtosecond supercontinuum with average power greater than 2 W. While the power is significantly higher than traditional femtosecond erbium-fiber based supercontinuum sources, the relative intensity noise is substantially lower than a continuous-wave supercontinuum with comparable average power.

A novel metal separation membrane by femtosecond laser microprocessing
Paper 7204-30 of Conference 7204
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Xichen M. Yang, Gang Wang, Jianbo Lei, Tianjin Polytechnic Univ. (China)

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The separation and filtration membrane is widely used in bio-medicine, purification of water and foodstuff industry. However, conventional membrane made from polymer, sintered metal and ceramic materials have some disadvantages: tortuous holes, smaller permeate flux and short using life. A novel metal membrane by fs laser microprocessing is presented to compete with conventional membrane. Three metal film of stainless, Al and Cu with 10~25μm are used as novel membrane materials. Laser microprocessing parameters have been optimized. It is shown that stainless film of 25μm thickness is the best membrane materials, its permeate flux has been increased by 6 times.

Ablation of aluminum-nitride films by nanosecond and femtosecond laser pulses
Paper 7201-46 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Vitaly E. Gruzdev, Robert D. Tzou, Univ. of Missouri, Columbia (United States); Ildar Salakhutdinov, Yuriy Danylyuk, Gregory W. Auner, Erik McCullen, Wayne State Univ. (United States)

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We present results of study of laser-induced ablation of AlN films with variable content of oxygen. The ablation was done by single nanosecond pulse at wavelength 248 nm, and by single femtosecond pulse at wavelength 775 nm in air at normal pressure. Ablation craters were inspected by Raman spectrometer, AFM, SEM, and Nomarski microscope. Chemical modification of material by nanosecond pulses around the ablation craters was detected for all samples with total absence of thermo-mechanical fracturing near the crater edges. The femtosecond pulses produced very gentle ablation with no signs of thermal or thermo-mechanical effects. We discuss mechanisms responsible for the observed effects.

Chirped-pulse long cavity femtosecond Cr:forsterite oscillator
Paper 7193-98 of Conference 7193
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Vladislav I. Shcheslavskiy, Denis A. Ivanov, Theo Lasser, Ecole Polytechnique Fédérale de Lausanne (Switzerland); Alexander N. Vasil'ev, Alexey M. Zheltikov, Lomonosov Moscow State Univ. (Russian Federation)

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Broadening the ultrashort laser pulses in Kerr-lens mode-locked Ti:sapphire lasers by net positive group delay dispersion has proven to be a fruitful concept for scaling the pulse energy directly obtainable from a laser. This paper presents for the first time theoretical and experimental results on high-energy low repetition rate (14MHz) Cr:forsterite oscillator operating in positive dispersion regime. Accurate dispersion adjustment is provided by intracavity prisms. The laser generates spectrum of 100nm and 40fs pulses. Output pulse energy is 30nJ, which is the highest energy per pulse obtained directly from Cr:forsterite oscillators up to date.

Development of a tool for nanostructuring and multiphoton imaging with nanojoule femtosecond laser pulses
Paper 7201-2 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): David Bruneel, Martin Schwarz, Fraunhofer-Institut für Biomedizinische Technik (Germany); Eric Audouard, Lab. Hubert Curien (France); Ronan Le Harzic, Fraunhofer-Institut für Biomedizinische Technik (Germany)

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An integrated tool combining control and diagnostic for nanoprocessing of bio-compatible and biological materials and also allowing multiphoton large area laser scanner microscopy has been developped. This multi-function compact device is of prime interest and can be considered as a novel tool for nanoprocessing in material science, nanobiotechnology, nanomedicine. Applications in biomedicine include, for example, optoporation, cells nanodrilling, nanocutting transfection of cells, deactivation of cell organelles or investigation of cell dynamics but also potentially useful in material science for the manufacture of waveguides, gratings, micro fluidic devices, nanocontainers, data storage, nanolithography, nanomarking,…

Optimizing stable mode-locked operation of Yb-doped femtosecond fiber laser
Paper 7195-90 of Conference 7195
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Mohamad Abdelalim, Yury Logvin, Univ. of Ottawa (Canada); Diaa A. Khalil, Ain Shams Univ. (Egypt); Hanan Anis, Univ. of Ottawa (Canada)

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We report on a novel simple configuration of an Yb-doped fiber laser cavity comprising only Yb-doped fiber and a saturable absorber element. Numerical results show that stable mode-locked operation does exist in such a laser cavity in a reasonable range of parameters. The conditions to obtain stable pulses are investigated as a function of the Yb-fiber bandwidth, length, and gain coefficient. The temporal and spectral behavior of the femtosecond pulses are also studied for different input parameters. The instability dynamics of the mode-locked pulse is also elucidated.

Parallel femtosecond laser processing with a computer-generated hologram
Paper 7201-48 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Satoshi Hasegawa, Utsunomiya Univ. (Japan)

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A computer-generated hologram provides the futures of high throughput and high light-use efficiency to femtosecond laser processing. In parallel femtosecond laser processing with a hologram, a precise control of diffraction peaks is indispensable to fabricate enormous numbers of nanometer-scale structures simultaneously. The optimized hologram has high uniformity of the diffraction peaks in a computer reconstruction. However, the uniformity is decreased by the spatial and temporal properties of the optical system. In this paper, we propose some optimization methods of the hologram to improve the uniformity and demonstrate the processing performance.

Self-phase modulation of mid-infrared femtosecond pulses in semiconductor materials
Paper 7197-44 of Conference 7197
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Satoshi Ashihara, Tokyo Univ. of Agriculture and Technology (Japan) and Japan Science and Technology Agency (Japan); Yusuke Kawahara, Tokyo Univ. of Agriculture and Technology (Japan)

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We investigate the self-phase modulation of mid-infrared pulses in semiconductor materials of Si, Ge, GaAs, and ZnSe, respectively. The mid-infrared pulses of 100 fs duration and 200 cm-1 bandwidth at the center wavelength around 3-7 micron are generated by the nonlinear frequency mixings. The generated mid-infrared pulses with micro-joule pulse energy are focused onto the semiconductor materials. At the peak intensity of more than 10 GW/cm2, the spectral reshaping and broadening are observed for Si, Ge, and GaAs. The output spectral bandwidth extends over 800 cm-1, accompanied by the nonlinear absorption. ZnSe shows weaker self-phase modulation, but has higher transmittance.

Waveguide fabrication with femtosecond laser pulse shaped by computer-generated hologram
Paper 7201-47 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Jun'ichi Suzuki, Masahiro Yamaji, Shuhei Tanaka, New Glass Forum (Japan)

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Femtosecond laser micromachining in glasses has been studied to fabricate optical devices, such as waveguides, splitters, resonators, and so on. These devices are written with irradiating many laser pulses whose energy is adequately reduced from maximum laser energy.
In this work, we fabricate an optical waveguide using a computer-generated hologram (CGH). We develop the CGH that can convert an intensity distribution of an input femtosedond laser beam into that of a line beam. The line beam shaped by the CGH is focused inside fused silica, and consequently, a linear waveguide of more than 1 mm long is created. This fabrication technique with CGH can provide higher laser energy efficiency and shorter machining time, since a single femtosecond laser pulse is used. Although the dot structure fabricated with CGH has been reported, the waveguide fabrication using CGH is first achievement, to our knowledge.

Tunable high-energy femtosecond soliton fiber laser based on hollow-core photonic bandgap fiber
Paper 7195-36 of Conference 7195
Date: Wednesday, 28 January 2009
Time: 8:00 AM – 8:30 AM

Author(s): Pascal Dupriez, Fianium Ltd. (United Kingdom); Frédéric Gérôme, Univ. de Limoges (France); Jonathan C. Knight, Univ. of Bath (United Kingdom); John Clowes, Fianium Ltd. (United Kingdom); William J. Wadsworth, Univ. of Bath (United Kingdom)

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A high power tunable femtosecond soliton-based source using a simple combination of a high energy fiber laser and hollow-core photonic bandgap fiber (HC-PBGF) is reported. Fiber amplified 5.5 ps pulses emitted at 1064 nm and strongly chirped by self-phase modulation are compressed in anomalously dispersive HC-PBGF enabling formation of 450 fs solitons. Wavelength tuneability is demonstrated through Raman self-frequency shift above 220nJ of input pulse energy. These solitonic pulses are then frequency doubled with remarkable conversion efficiency in a nonlinear crystal to demonstrate a femtosecond green laser tunable from 534 nm to 548 nm.

Femtosecond fiber CPA system with 325-W average power
Paper 7195-39 of Conference 7195
Date: Wednesday, 28 January 2009
Time: 9:10 AM – 9:30 AM

Author(s): Tino Eidam, Fabian Röser, Enrico Seise, Thomas Gottschall, Steffen Hädrich, Jan Rothhardt, Friedrich-Schiller-Univ. Jena (Germany); Thomas Schreiber, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany); Jens Limpert, Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)

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We report on an ytterbium-doped fiber CPA system delivering 325 W of average power at 40 MHz repetition rate corresponding to 8.2 µJ pulse energy. The pulse duration is as short as 375 fs resulting in 22 MW of peak power. To the best of our knowledge this is the highest average output power of a solid state laser in the ultra-short pulse regime.

Energy scaling of femtosecond and picosecond fiber oscillators beyond the microjoule level
Paper 7195-40 of Conference 7195
Date: Wednesday, 28 January 2009
Time: 9:30 AM – 9:50 AM

Author(s): Bülend Ortac, Martin Baumgartl, Oliver Schmidt, Friedrich-Schiller-Univ. Jena (Germany); Ammar A. Hideur, Univ. de Rouen (France); Isabelle Sagnes, Ctr. National de la Recherche Scientifique (France); Arnaud Garnache, Univ. Montpellier II (France); Jens Limpert, Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)

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We report on the generation of microjoule level picosecond and sub-picosecond pulses from a mode-locked Yb-doped LMA fiber laser operating in the purely normal dispersion regime. The self-starting oscillator stabilized with slow relaxation semiconductor SAM emits 11 W of average power at a pulse repetition rate of 10 MHz, corresponding to a pulse energy of 1.1 µJ. The laser produces a 0.4 nm narrow emission line with 310 ps output pulses. In femtosecond operation, the oscillator stabilized with fast relaxation SAM emits 9 W of average power at a pulse repetition rate of 9.7 MHz, corresponding to a pulse energy of 927 nJ. The laser produces positively chirped output pulses of 8 ps, which are compressed down to 711 fs, corresponding to megawatt peak power. To our knowledge this is the first time that mode-locked fiber oscillators can generate higher pulse energies of beyond microjoule-level at high average output power.

All polarization-maintaining fiber chirped-pulse amplification system for microjoule femtosecond pulses
Paper 7195-41 of Conference 7195
Date: Wednesday, 28 January 2009
Time: 9:50 AM – 10:10 AM

Author(s): Shian Zhou, Cornell Univ. (United States) and Sunx Ltd. (Japan); Tetsuji Takamido, Rakesh Bhandari, Sunx Ltd. (Japan); Andy Chong, Frank W. Wise, Cornell Univ. (United States)

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We report a practical fiber source of femtosecond pulses with microjoule energies. The all-fiber system produces 480 fs pulses at 220 kHz repetition rate and 5 J pulse energy. The system employs polarization-maintaining fiber for stability, and the double-clad amplifier is pumped via fiber combiners. In addition to the main performance parameters, this integrated system offers excellent beam quality (M2 < 1.1), pulse contrast (40 dB), polarization extinction ratio (36 dB), and environmental stability for long-term operation.

Femtosecond carrier dynamics in quasi-one-dimensional topological compounds
Paper 7214-52 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 11:11 AM – 11:39 AM

Author(s): Yasunori Toda, Hokkaido Univ. (Japan)

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Due to the recent progress of material science, quasi-one-dimensional (1D) materials provide an opportunity for investigating the influence of topology and dimensionality of materials on their optical and electrical properties. In this study, we report the phase transition properties of such quasi-1D compounds by utilizing an ultrafast optical spectroscopy. Photoinduced nonequilibrium carrier dynamics yield characteristic features around the phase transition temperatures. We also discuss the influence of topology and dimensionality on the phase transitions by using polarization and excitation energy dependences of the transient signals and their spatial characteristics.

Multiscale modeling of phase changes during femtosecond laser metal interaction
Paper 7202-10 of Conference 7202
Date: Wednesday, 28 January 2009
Time: 4:00 PM – 4:30 PM

Author(s): Lan Jiang, Xin Li, Beijing Institute of Technology (China); Hai-Lung Tsai, Missouri Univ. of Science and Technology (United States)

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A femtosecond pulse in some aspects fundamentally changes the laser-material interaction mechanism compared with a long pulse. Although many studies have been conducted, it remains a challenge to fundamentally understand the dissipation of the absorbed energy into lattice and the corresponding phase change mechanisms. This paper studies the femtosecond laser pulse-train processing of the metal thin films. In our multiscale model, molecular dynamics simulation is employed in the ablation subsystem and the improved two-temperature model is applied to heat conduction subsystem. The phase change mechanisms are investigated with the focus on melting and vaporization.

MEMS for femtosecond pulse shaping applications
Paper 7209-8 of Conference 7209
Date: Wednesday, 28 January 2009
Time: 4:40 PM – 5:00 PM

Author(s): Ariana Rondi, Jérôme Extermann, Stefan M. Weber, Univ. de Genève (Switzerland); Jonathan D. Roslund, Matthias H. Roth, Princeton Univ. (United States); Luigi Bonacina, Univ. de Genève (Switzerland); Herschel A. Rabitz, Princeton Univ. (United States); Jean-Pierre Wolf, Univ. de Genève (Switzerland)

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There are many potential applications for MEMS micromirror devices for femtosecond pulse shaping applications. Their broadband reflectivity gives them an advantage in comparison to devices such as liquid crystal- and acousto-optical modulators because of the possibility to directly address UV-absorbing molecules. The identification and discrimination of biomolecules which exhibit almost the same spectra has sparked some interest in the last years as it allows real-time, environmental, optical monitoring. With quantum control schemes, a distinction between quasi identical biomolecules (Riboflavin and Flavin Mono Nucleotide) could be performed. Here, we present the last developments using the FhG-IPMS MEMS phase former capable of accomplishing such goals.

Investigation of the photorefractive effect in lithium-niobate crystals using femtosecond laser pulses
Paper 7197-29 of Conference 7197
Date: Wednesday, 28 January 2009
Time: 5:20 PM – 5:40 PM

Author(s): Dominik Maxein, Johanna Bückers, Daniel Haertle, Karsten Buse, Univ. Bonn (Germany)

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The photorefractive effect plays an important role in many applications of lithium niobate crystals (LiNbO3). We compare in this contribution writing and erasure of gratings in Fe-doped LiNbO3 with fs laser pulses and with continuous-wave light: Holographic scattering is pronounced for cw, but weaker or even absent in some samples for fs pulses.
Furthermore, in oxidized LiNbO3:Fe, the writing times with pulses are much smaller than those obtained with cw light.
Supported by the DFG and the Deutsche Telekom AG.

Probing photoelectronic emission from nanostructures based on conductive atomic force microscopy and femtosecond laser illumination
Paper 7201-39 of Conference 7201
Date: Wednesday, 28 January 2009
Time: 5:20 PM – 5:40 PM

Author(s): Nipun Misra, David J. Hwang, Costas P. Grigoropoulos, Univ. of California, Berkeley (United States); Emmanuel Stratakis, Emmanuel Spanakis, Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (Greece) and Univ. of Crete (Greece) and Technological Educational Institute of Crete (Greece); Costas Fotakis, Panagiotis Tzanetakis, Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (Greece)

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Transient optical absorption upon femtosecond pulse irradiation in lithium-niobate crystals
Paper 7197-37 of Conference 7197
Date: Thursday, 29 January 2009
Time: 10:00 AM – 10:20 AM

Author(s): Satoshi Ashihara, Tokyo Univ. of Agriculture and Technology (Japan) and Japan Science And Technology Agency (Japan); Satoru Sasamoto, Tokyo Univ. of Agriculture and Technology (Japan); Junji Hirohashi, Oxide NIMS Corp. (Japan)

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Transient optical absorption induced by two-photon excitation of carriers in lithium niobates is investigated by the pump-probe experiments. The measured samples are the undoped and MgO-doped lithium niobates of either congruent or stoichiometric composition. In any of the samples, the absorption at the wavelength of 800 nm builds up within 100 fs and lasts for longer than 100 ps. The pump-intensity dependence as well as the amplitude of the induced absorption is similar among the measured samples regardless of the Li/Nb ratio or the MgO-doping. The results give new insight into the carrier relaxation dynamics in this ferroelectric crystal.

Femtosecond pump-probe characterization of high-pressure grown AlxGa1-xN single crystals
Paper 7216-60 of Conference 7216
Date: Thursday, 29 January 2009
Time: 12:00 PM – 12:15 PM

Author(s): Roman Sobolewski, Jie Zhang, Univ. of Rochester (United States); Andrey Belousov, Jan Jun, Kathrin Hametner, Detlef Günther, Janusz Karpinski, Bertram Batlogg, ETH Zürich (Switzerland)

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We report our experimental studies on the time-resolved carrier dynamics in high quality AlxGa1-xN single crystals, grown using a solution technique in a high nitrogen gas pressure system. Our optical measurements were performed using a femtosecond, pump-probe spectroscopy, by invoking a two-photon absorption of the pump beam and scanning the transient differential transmissivity (ΔT/T) signal of the probe beam. We were able to determine that the optical bandgap of AlxGa1-xN (x = 0.83-0.85) was in the 5.904-5.961 eV range. Our time-resolved ΔT/T transients, consisted of an initial 125-fs electron-phonon relaxation, followed by a much slower, ~75-ps-long, decay.

High speed analog-to-digital conversion with silicon photonics
Paper 7220-10 of Conference 7220
Date: Monday, 26 January 2009
Time: 1:30 PM – 2:00 PM

Author(s): Charles W. Holzwarth, Reja Amatya, Mohammad Araghchini, Jonathan R. Birge, Hyunil Byun, Li-Jin Chen, Marcus S. Dahlem, Nicole A. DiLello, Fuwan Gan, Judy L. Hoyt, Erich P. Ippen, Franz X. Kärtner, Anatoly M. Khilo, Jung Won Kim, Meekyung Kim, Ali R. Motamedi, Jason S. Orcutt, Matthew J. Park, Michael H. Perrott, Milos A. Popovic, Rajeev J. Ram, Henry I. Smith, Guirong Zhou, Massachusetts Institute of Technology (United States); Steven J. Spector, Theodore M. Lyszczarz, Michael W. Geis, Donna M. Lennon, Jung U. Yoon, Matthew E. Grein, Robert T. Schulein, MIT Lincoln Lab. (United States)

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Sampling rates of high-performance electronic analog-to-digital converters (ADC) are fundamentally limited by the timing jitter of the electronic clock. This limit is overcome in photonic ADC’s by taking advantage of the ultra-low timing jitter of femtosecond lasers. We have developed designs and strategies for a photonic ADC that is capable of 40 GSa/sec at 8 bits. This system requires a femtosecond laser with a repetition rate of 2 GHz and timing jitter below 30 fs. In addition to a femtosecond laser this system calls for the integration of multiple photonic components including: a broadband modulator, optical filter banks, and photodetectors.

In vivo multiphoton tomography using a high NA GRIN microendoscope
Paper 7183-44 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 8:00 AM – 8:25 AM

Author(s): Karsten König, JenLab GmbH (Germany)

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Multiphoton tomographs based on femtosecond laser and GRIN lens technology in combination with flexible scan heads have been developed for clinical high-resolution tissue imaging and small animal research. The novel multiphoton tissue tomograph possesses an articulated mirror arm in combination with a flexible scan head which includes galvoscanner, a piezodriven focusing optics and a PMT photodetector as well as a rigid GRIN microendoscope. 250 MHz fiber based femtosecond lasers as well as 80 MHz tunable Ti:Sa lasers have been tested as source for two-photon SHG , autofluorescence, and FLIM imaging

Optimizing CARS signal using coherent control methods
Paper 7183-25 of Conference 7183
Date: Monday, 26 January 2009
Time: 9:45 AM – 10:00 AM

Author(s): Vladimir S. Malinovsky, MagiQ Technologies, Inc. (United States)

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Recently we have shown that linearly chirped ultrafast pulses can be utilized to maximize CARS coherence. The method, uses the chirp sign variation at the central time, and gives robust adiabatic excitation of the resonant vibrational mode. Here we analyze influence of fast decoherence in the molecular samples and compare robustness and selectivity of the method to other excitation proposals. We demonstrate that the proposed adiabatic method allows achieving chemical sensitivity with high resolution and can be used to obtain CARS signal in molecular systems with coherence times of several hundred of femtoseconds.

Ultrafast Fiber Lasers
Date: Wednesday, 28 January 2009
Time: 1:30 PM – 5:30 PM

Author(s): Martin E. Fermann, IMRA America, Inc. (United States)

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Evaluation of effects of microstructures on titanium surfaces, applied by femtosecond laser, on human auricular chondrocytes by in-vitro cell culture
Paper 7161C-305 of Conference 7161C
Date: Saturday, 24 January 2009
Time: 9:20 AM – 9:40 AM

Author(s): Slavomir Biedron, Justus F. R. Ilgner, Univ. Hospital Aachen (Germany); Elena Fadeeva, Boris N. Chichkov, Laser Zentrum Hannover e.V. (Germany); Martin Westhofen M.D., Univ. Hospital Aachen (Germany)

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This study was performed to evaluate how the influence of selected microstructures on titanium surfaces on the growth of human auricular chondrocytes can be studied in vitro. Human chondrocytes were seeded on tissue culture dishes and cultured for up to 3 passages. The phenotype was monitored by means of light microscopy and immunohistochemistry. Titanium discs in samples of 5mm diameter and 0,25mm thickness were structured by means of a Ti:Sapphire femtosecond laser. These samples were incubated with subcultured chondrocytes and the cells were grown to confluence. If the cells are seeded on titanium samples at a density of 0,5 x 10e4 cells/cm2 it takes 5-7 days until the discs are overgrown. Using freshly harvested cartilage about 10e7 cells/g can be obtained.

Selective cellular membrane ablation by the enhanced near-field scattering of femtosecond laser light by membrane-bound gold nanostructures
Paper 7203-3 of Conference 7203
Date: Sunday, 25 January 2009
Time: 9:20 AM – 9:40 AM

Author(s): Daniel S. Eversole, Ozgur Ekici, Rick Harrison, Nicholas J. Durr, Adela Ben-Yakar, The Univ. of Texas at Austin (United States)

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The intense near-field scattering by noble-metal nanoparticles in the near-infrared wavelength regime can be exploited to initiate plasma-mediated ablation for the precise manipulation of cellular membranes. We describe a novel, non-thermal femtosecond laser ablation process for selective cancer removal utilizing gold nanoparticles. The membrane of epithelial breast cancer cells (MDA-MB-468) was targeted in-vitro with 50 nm gold nanospheres functionalized with anti-EGFR antibodies. We observed photoinduced permeability of cellular membranes upon exposure to 250-fs, 760 nm laser pulses with as little as 1.4 mJ/cm2 laser fluence, as determined by FITC-Dextran intake. Labeled cells showed 33 times reduction in laser fluence necessary for membrane permeability when compared to unlabeled cells.

Ultrafast semiconductor quantum optics
Paper 7214-13 of Conference 7214
Date: Sunday, 25 January 2009
Time: 3:12 PM – 3:40 PM

Author(s): Rudolf Bratschitsch, Univ. Konstanz (Germany)

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Semiconductor quantum dots are promising systems for robust and scalable quantum information processing. Ultrafast sequences of coherent quantum operations may be envisioned with femtosecond light pulses, if the involved quantum states are separated by at least tens of meV. We present two-color femtosecond pump-probe spectroscopy on a single self-assembled CdSe/ZnSe quantum dot. The transient quantum dynamics is probed with resonant excitation and detection. Ultrafast Coulomb renormalization and single exciton gain are observed with these first resonant pump-probe measurements on a single-electron system. We will also discuss strategies to increase the light-quantum dot coupling via optical nanoantennas and microresonators.

High-throughput on-chip In vivo neural regeneration studies using femtosecond laser nano-surgery and microfluidics
Paper 7203-42 of Conference 7203
Date: Sunday, 25 January 2009
Time: 3:20 PM – 3:50 PM

Author(s): C. Rohde, C. Gilleland, C. Samara, F. Zeng, Mehmet F. Yanik, Massachusetts Institute of Technology (United States)

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We present on-chip technologies for high-throughput screening of small-animal (C. elegans), and also use of these technologies for in vivo discovery of genetic/drug factors in neural regeneration. We demonstrate high speed microfluidic sorters, which can rapidly isolate and immobilize awake animals in a well-defined geometry for screening phenotypic features at sub-cellular resolutions non-invasively without use of anesthesia or cooling. We show use of these technologies for three-dimensional two-photon imaging and femtosecond laser nano-surgery on awake animals for high-throughput neural degeneration and regeneration studies. We show integrated chips containing individually addressable screening-chambers for incubation and exposure of individual worms to RNAi/compounds, and high-resolution time-lapse imaging of many immobilized animals on a single chip without anesthesia. We report devices for delivery of compound libraries in standard multi-well plates to microfluidic devices, and also for rapid dispensing of screened animals into multi-well plates. When used in various combinations, these devices facilitate a variety of high-throughput assays including mutagenesis, RNAi and drug screens at sub-cellular resolution on awake animals, as well as large-scale on-chip in vivo neural degeneration and regeneration studies using femtosecond laser microsurgery. We will report the recent advances we made using these technologies.

Ultra-compact (palm-top size), low-cost, maintenance-free (>3000 h), 1.5-kW-peak-power diode-pumped femtosecond solid-state laser source for multiphoton microscopy
Paper 7183-114 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Shogo Yamazoe, Tadashi Kasamatsu, FUJIFILM Advanced Research Labs. (Japan)

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We demonstrate a novel practical femtosecond laser source, which is, to our knowledge, the smallest size and potentially low cost. The innovation is the simple linear-cavity design utilizing soliton mode-locking induced by precise group velocity dispersion control. Average output power of 680 mW and pulse width of 162 fs were obtained at around 1045 nm from a 980-nm diode-pumped Yb3+:KY(WO4)2 laser. The pulse repetition rate was 2.8 GHz, leading to a pulse peak power of 1.5 kW, which is sufficient for biomedical imaging. The laser module including the laser diode pump system has a footprint of only 8×4 cm2. Stable operation of 3000 hours was demonstrated with fluctuation of less than 10%.

Enhancing two-color absorption, self-phase modulation, and Raman microscopy signatures in tissue with femtosecond laser pulse shaping
Paper 7183-31 of Conference 7183
Date: Monday, 26 January 2009
Time: 1:00 PM – 1:25 PM

Author(s): Warren S. Warren, Sr., Martin C. Fischer, Duke Univ. (United States); Ivan Piletic, Stanford Univ. (United States); Dan Fu, Thomas E. Matthews, Prathyush Samenini, Duke Univ. (United States)

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Nonlinear microscopies (most commonly, two-photon fluorescence, second harmonic generation, and CARS) have had notable successes in imaging a variety of endogenous and exogenous targets in recent years. These methods which generate light at a color different from any of the exciting laser pulses, which makes the signal relatively easy to detect. Our work has focused on developing microscopy techniques using a wider range of nonlinear signatures (two-photon absorption of nonfluorescence species, self phase modulation) which have some specific advantages- for example, in recent papers we have shown that we can differentiate between different types of melanin in pigmented lesions, can image hemoglobin and its oxygenation, and can measure neuronal firing. In general, these signatures do not generate light at a different color, and we rely on the advantages of femtosecond laser pulse shaping methods to amplify the signals and make them visible (for example, using heterodyne detection of the induced signal with one of the copropagating laser pulses). Here we extend this work to stimulated Raman and minimal-color CARS geometries. In the simplest experiments, both colors arise from filtering a single fs laser pulse, then modulating afterwards; in other cases, we demonstrate that spectral hole refilling can retain high frequency resolution in Raman and CARS geometries with femtosecond laser pulses.

Synthesis of size-tunable polymer protected metallic nano-alloys by femtosecond laser-based ablation and seed growth
Paper 7192-22 of Conference 7192
Date: Tuesday, 27 January 2009
Time: 8:40 AM – 9:00 AM

Author(s): Sébastien Besner, Andrei V. Kabashin, Ecole Polytechnique de Montréal (Canada); Francoise M. Winnik, Univ. of Montréal (Canada); Michel Meunier, Ecole Polytechnique de Montréal (Canada)

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A green femtosecond laser-based method has been developed to produce stable, size tunable (3 to ~100nm) and low dispersed gold nanoparticles. This method implies the formation of initial nano-sized seeds (<10nm) by laser ablation of a gold target immersed in an aqueous solution of biopolymers and the ripening of those seeds by a secondary femtosecond supercontinuum irradiation. The formation of several nano-alloys (AgAu, AuCu, AuCo, etc.) was also achieved by irradiating a mixture of different elemental colloidal compounds. Biopolymers of different concentration enabled in-situ surface functionalization and size control during the process. Such nanoparticles are for great interest in biomedical applications.

On the use of femtosecond lasers to fabricate small optical instruments made from fused-silica monoliths
Paper 7203-25 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 11:40 AM – 12:10 PM

Author(s): Philippe Bado, Mark A. Dugan, Ali A. Said, Thomas F. Haddock, Translume, Inc. (United States)

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We present some small optical instruments fabricated with femtosecond laser pulses. These instruments, made from monolithic fused silica substrates, incorporate an extensive collection of optical and micro-mechanical elements. A single manufacturing step was used to define both the optical and the mechanical features. This approach dramatically simplifies overall fabrication and eliminates alignment issues associated with sequential fabrication processes.

On the use of femtosecond lasers to fabricate small optical instruments made from fused-silica monoliths
Paper 7201-25 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 11:40 AM – 12:10 PM

Author(s): Philippe Bado, Mark A. Dugan, Ali A. Said, Thomas F. Haddock, Translume, Inc. (United States)

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We present some small optical instruments fabricated with femtosecond laser pulses. These instruments, made from monolithic fused silica substrates, incorporate an extensive collection of optical and micro-mechanical elements. A single manufacturing step was used to define both the optical and the mechanical features. This approach dramatically simplifies overall fabrication and eliminates alignment issues associated with sequential fabrication processes.

Integration of Bragg grating waveguides and microfluidic channels with femtosecond laser irradiation for refractive index sensing
Paper 7207-17 of Conference 7207
Date: Tuesday, 27 January 2009
Time: 2:00 PM – 2:20 PM

Author(s): Valeria A. Maselli, Jason R. Grenier, Stephen Ho, Peter R. Herman, Univ. of Toronto (Canada)

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Microfluidic channels and Bragg Grating Waveguides (BGWs) were simultaneously fabricated inside fused silica glass by means of femtosecond laser exposure followed by HF chemical etching. Evanescent field penetration of the waveguide mode into the parallel microfluidic channel induced Bragg resonant wavelength shifts which enabled refractive index characterization of the fluidic medium in the 1 to 1.442 range. Device geometry, wall smoothness and Bragg resonance were optimized for high sensitivity sensing at 1550 nm wavelength, while reference gratings were employed for temperature and strain compensation. The device opens new directions for optical sensing in 3D optofluidic and reactor microsystems.

Two-photon polymerization for fabrication of three-dimensional micro- and nanostructures over a large area
Paper 7204-13 of Conference 7204
Date: Tuesday, 27 January 2009
Time: 2:20 PM – 2:40 PM

Author(s): Mangirdas Malinauskas, Vytautas Purlys, Marius Rutkauskas, Roaldas Gadonas, Vilnius Univ. (Lithuania)

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Two-photon polymerization has emerged as a technology for rapid fabrication of three-dimensional micro-structures with nano-scale resolution. In most cases, femtosecond Ti:Sapphire laser was applied as an irradiation source to solidify the photoresin. Here, we present a system for two-photon polymerization which utilizes Yb:KGW femtosecond laser’s second harmonic to initiate nonlinear polymerization. Shorter irradiation wavelength enables one to focus laser beam to a smaller spot. High repetition rate and high average power capacitates to fabricate three-dimensional structures over large area rapidly. Results proving resolution to be up to ~100 nm and some micro-structures over millimeter area are presented in this talk.

Chirped four-wave mixing in the largely normal dispersion regime from femtosecond pulse-pumped photonic crystal fiber
Paper 7195-99 of Conference 7195
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Haohua Tu, Zhi Jiang, Daniel L. Marks, Stephen A. Boppart M.D., Univ. of Illinois at Urbana-Champaign (United States)

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A four-wave mixing process of 4700 cm-1 Stokes-shift is stimulated by pumping a 20-cm commercial large-mode-area photonic crystal fiber with amplified Ti:sapphire femtosecond pulses. The phase-matching condition is realized through an intermodal scheme which promotes the process in the largely normal dispersion regime of the fiber. The walk-off effect of the interacting pulses is minimized by introducing an initial chirp to the pump pulses. Conversion efficiency over 7% from near-infrared pump input to visible anti-Stokes signal can be achieved.

Continuum generation in optical fiber for high-resolution holographic coherence domain imaging application
Paper 7197-50 of Conference 7197
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Linghui Li, Vitaly E. Gruzdev, Ping Yu, Jinn K. Chen, Univ. of Missouri, Columbia (United States)

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High pulse energy continuum generation in a conventional silica-based optical fiber is studied and applied to a holographic coherence domain imaging system. In our experiment, the pump laser is a femtosecond laser with a pulse width of 180 fs, wavelength of 775 nm and repetition rate of 1 KHz. The FWHM of the femtosecond laser is 5.4 nm. We measured the FWHM of the continuum generation as a function of incident pulse energy. The maximum FWHM is about 8x higher than that of the input pulses. The stability was analyzed by using a frequency domain Fourier transform method.

Femtosecond, nanosecond, and continuous-wave nonlinear optical properties of (H2)2SnPc, Sn(OH)2Pc, Sn(Cl)2Pc studied using Z-scan technique
Paper 7197-40 of Conference 7197
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Venugopal R. Soma, Univ. of Hyderabad (India)

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Phthalocyanines and their analogues/derivatives are macromolecules with large number of delocalized electrons possessing attractive third-order nonlinear optical properties with prominent applications in the areas of optical limiting and ultrafast all-optical switching. Here we present our results on the femtosecond, nanosecond, and continuous wave (cw) experimental nonlinear optical studies of Sn(H2)2Pc, Sn(OH)2Pc, and Sn(Cl)2Pc using the Z-scan technique

Temperature-dependent properties of fiber-Bragg gratings generated with UV-femtosecond pulses and with UV-nanosecond pulses
Paper 7195-67 of Conference 7195
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Eric Lindner, Martin Becker, Sven Brückner, Manfred W. Rothhardt, Hartmut Bartelt, Institute of Photonic Technology (Germany)

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The temperature dependent properties of fiber Bragg gratings are not only of importance for understanding the general stability and degradation properties of such gratings, but are also essential for sensor applications, such as for direct temperature measurements or for general fiber sensing at high temperatures. We have therefore compared the annealing properties of fiber Bragg gratings made under different interferometric inscription conditions, namely with UV femtosecond and with UV nanosecond pulses in a modified Talbot interferometer setup. Different types of fibers such as Ge doped fibers and pure silica fibers have been used for comparison of the achieved properties. The gratings inscribed with a UV nanosecond excimer laser show specific annealing properties depending on the energy density and exposure duration besides the expected color center formation (for low energy density TypeI gratings) or the structural damages in the glass material (for high energy density TypeII gratings). Furthermore, nanosecond gratings with certain characteristics show temperature induced grating reflectivity changes which indicate stress in the exposed area of the fiber. The classification of refractive index modifications in the fiber and of grating types (TypeI/II) is investigated and compared for both the UV femtosecond and the nanosecond laser pulse inscribed gratings.

Demonstration of inscription and ablation of phase masks for the production of 1st, 2nd, and 3rd order FBG gratings using femtosecond light
Paper 7205-36 of Conference 7205
Date: Wednesday, 28 January 2009
Time: 3:50 PM – 4:10 PM

Author(s): Graham N. Smith, Aston Univ. (United Kingdom); Kyriacos Kalli, Cyprus Institute of Technology (Cyprus); Ian Bennion, Kate Sugden, Aston Univ. (United Kingdom)

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We present, to our knowledge, the first example of femtosecond inscription/ablation of phase masks used to produce 1st, 2nd and 3rd order Fibre Bragg Gratings in SMF-28. The work demonstrates the proof of concept and flexibility for the use of femtosecond lasers to make complex and reproducible phase masks. This approach has the potential to rival e-beam fabrication of phase masks and has the advantage of not requiring an acid etch stage.

Using these phase masks, 1st and higher order fibre Bragg gratings were inscribed in a hydrogen loaded photosensitive fibre and reflectivities over 30dB were attained.

Ultrafast far-infrared optics of carbon nanotubes
Paper 7214-9 of Conference 7214
Date: Sunday, 25 January 2009
Time: 1:20 PM – 1:48 PM

Author(s): Christian Frischkorn, Freie Univ. Berlin (Germany)

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Time-resolved THz spectroscopy is used to investigate the carrier dynamics in carbon nanotubes, which allows to monitor the energy relaxation of the optically excited electrons. The energy of the pump pulse initially deposited into the electronic system is rapidly dissipated to only few strongly coupled optical phonons which heat up within few hundreds of femtoseconds. Subsequent cooling of these phonon modes is observed on a picosecond time-scale which is substantially faster in nanotubes than in graphite pointing to stronger lattice anharmonicities. Temperature dependent measurements show the hot phonon decay proceeding via generation of cold phonons like high-frequency optical phonon and radial breathing modes.

Imaging neuronal population activity with random access two-photon microscope
Paper 7186-26 of Conference 7186
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Shaoqun Zeng, Huazhong Univ. of Science and Technology (China)

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Two-photon microscopy has grown up to be an important technique in biology research, particularly in exploring the neuronal functions of the neurons. With large penetration depth and three-dimensional selectivity, this technique has been able to address the neuro-computing in brain slice or even in live animals. However, its imaging rate is limited by the mechanic scanning mechanism and cannot satisfy the requirement for imaging the encoding pattern of the neuron populations or integrating sites such as the spines. Laser beam steering with acousto-optic deflector (AOD) provides a fast scanning rate, as well as high precision, and high stability due to its inertial-free scanning mechanism. Moreover, 2D AOD scanning allows fast random access to each site of interest, and can thus devote dwell time to pixels of interest and increase both the signal-to-noise ratio and the frame-capture rate. However, scanning femtosecond laser beam with AOD is frustrated by the dispersive nature of the acousto-optic effect and crystal material. This presentation first shows a novel method to solve the problem of dispersion compensation. Based on this dispersion compensated AOD scanner, a random scanning two-photon microscope has been implemented to provide fast and flexible imaging rate with higher signal to noise ratio. A theoretical analysis is presented to explain the evolution of the femtosecond laser pulse in this kind of microscope. Finally, biological experiment is demonstrated to show the potential of recording fast neuronal activities with this technique.

In vivo multiphoton tomography in skin aging studies
Paper 7161A-116 of Conference 7161A
Date: Saturday, 24 January 2009
Time: 2:15 PM – 2:30 PM

Author(s): Karsten König, JenLab GmbH (Germany)

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Multiphoton tomography based on high resolution optical sectioning of the epidermis and the upper dermis has been used to analyze the morphology of the epidermal-dermal junction as well as the ratio of elastin to collagen (SAAID index).
The signal of elastin and intracellular endogenous fluorophores was obtained by two-photon excitation whereas collagen structures were imaged by the detection of second harmonic generation (SHG).
The in vivo measurements on volunteers were performed with the novel multiphoton tissue tomograph based on a compact femtosecond near infrared laser system and a flexible scan and detector head.

Ultrafast adaptive nanooptics
Paper 7214-10 of Conference 7214
Date: Sunday, 25 January 2009
Time: 1:48 PM – 2:16 PM

Author(s): Walter Pfeiffer, Univ. Bielefeld (Germany); Tobias Brixner, Dmitri V. Voronine, Univ. Würzburg (Germany); F. Javier Garcia de Abajo, Consejo Superior de Investigaciones Científicas (Spain); Martin Aeschlimann, Univ. Kaiserslautern (Germany); Michael K. Bauer, Christian-Albrechts-Univ. zu Kiel (Germany)

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Control of spatial and temporal properties of near-fields provides fascinating possibilities for nanoscale spectroscopy and manipulation of quantum systems. Recent progress to flexibly control such near-fields using optimally polarization-shaped femtosecond laser pulses is presented.

Photoinduced ultrafast structural dynamics of nanomaterials
Paper 7214-14 of Conference 7214
Date: Sunday, 25 January 2009
Time: 4:00 PM – 4:28 PM

Author(s): Jau Tang, Pying Yu, Po-Tze Tai, Sheng-Hsien Lin, Academia Sinica (Taiwan)

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We will report our study of photoinduced structural dynamics of nanomaterials of various shapes and sizes by a femtosecond laser heating pulse as detected by time-resolved electron diffraction or transient optical absorption. This work improves the understanding of nanoscale heat transfer and the ultrafast structural dynamics in nanomaterials such as thin films, spheres, prisms, disks, rods, pyramids and cubes. This work allows us to elucidate the roles of dynamic expansion/contraction and the more well-known static linear expansion.

Multiphoton microscopy of near infrared dyes
Paper 7183-110 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Siavash Yazdanfar, Chun Zhan, Chulmin Joo, GE Global Research (United States); Mikhail Berezin, Samuel Achilefu, Washington Univ. in St. Louis School of Medicine (United States)

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We describe multiphoton microscopy using a compact, turnkey femtosecond fiber to excite a new class of near infrared carbocyanine dyes. This system offers advantages in penetration depth, contrast, and simplicity as compared to conventional multiphoton microscopy.

New method to measure laser-beam spatial parameters
Paper 7194-6 of Conference 7194
Date: Monday, 26 January 2009
Time: 11:10 AM – 11:30 AM

Author(s): George Nemes, ASTiGMAT (United States); Magda Ulmeanu, Marian Zamfirescu, National Institute for Lasers, Plasma and Radiation Physics (Romania)

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A new method to measure the laser beam spatial parameters (waist size, divergence, Rayleigh range, beam propagation ratio) is proposed and experimentally verified. The method is based on rotating cylindrical optics (VariSpot by ASTiGMAT) and measuring the beam sizes in a fixed plane, as opposed to the conventional method of measuring different beam sizes at different positions along the beam axis. Experimental results on a femtosecond laser beam measured using both the classical and the new method reveal a satisfactory agreement between the two methods.

Random lasing from quantum-dot colloids suspended polymer
Paper 7194-11 of Conference 7194
Date: Monday, 26 January 2009
Time: 1:50 PM – 2:10 PM

Author(s): Seiji Takeda, Minoru Obara, Keio Univ. (Japan)

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We experimentally demonstrate Random Lasing (RL) using quantum dots (QD) colloids as laser gain medium. QD will cover the whole visible range of the spectrum. QD colloids (CdSe coated by ZnS) are suspended inside polymer (PMMA) with scatterers (TiO2 particles), and stimulated by SHG of Ti: sapphire femtosecond laser pulses. We measured the emission intensity and spectrum from the medium, and discuss the oscillating modes with FDTD methods. Our results will show the possibility of RL application for new light emitting device.

Large aperture chirped-Bragg gratings in PTR glass for fs-pulse stretching/compression
Paper 7195-11 of Conference 7195
Date: Monday, 26 January 2009
Time: 2:20 PM – 2:40 PM

Author(s): Vadim I. Smirnov, Ion Cohanoshi, Eugeniu V. Rotari, OptiGrate (United States); Leonid B. Glebov, College of Optics & Photonics/Univ. of Central Florida (United States)

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This paper reports on latest developments of chirped Bragg gratings manufactured in photo thermo refractive glass for femtosecond pulses stretching/compression. High efficiency 30 mm thick gratings are developed for 1050 and 1550 nm with bandwidth exceeding 20 nm.

Enhanced three-photon-excited photoluminescence in transition-metal-doped semiconductor quantum dots
Paper 7224-21 of Conference 7224
Date: Monday, 26 January 2009
Time: 2:30 PM – 3:00 PM

Author(s): Wei Ji, National Univ. of Singapore (Singapore)

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We present a theoretical model on three-photon absorption (3PA) cross-sections in semiconductor quantum dots (QDs) and compare it to the femtosecond Z-scan data on CdSe, ZnS and ZnSe/ZnS QDs. In addition, we also demonstrate the enhancement of 3PA in transition-metal doped ZnSe/ZnS QDs. Taking into account of the enhancement in three-photo-excited photoluminescence, such double enhancements make ZnSe/ZnS QDs doped with transition-metal ions a promising candidate for bio-imaging applications.

Fiber lasers for CARS microscopy
Paper 7183-24 of Conference 7183
Date: Monday, 26 January 2009
Time: 5:20 PM – 5:45 PM

Author(s): Frank W. Wise, Cornell Univ. (United States)

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Development toward a stable fiber source of tunable pulses for CARS microscopy will be reported. A stable oscillator supplies high-energy and transform-limited picosecond or femtosecond pulses. Initial results on the generation of synchronized tunable pulses for Raman excitation will be presented.

Rotational second harmonic generation endoscopy with 1µm fiber laser system
Paper 7172-24 of Conference 7172
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Gangjun Liu, Tuqiang Xie, Lingfeng Yu, Ivan V. Tomov, Beckman Laser Institute (United States); Jianping Su, Univ. of California, Irvine (United States); Zhongping Chen, Beckman Laser Institute (United States) and Univ. of California, Irvine (United States)

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We present a kind of rotational two photon mciroendoscopy for 1µm fiber femtosecond laser. The fiber laser provide ultrashort femto-second pulses with center wavelength at 1.034µm and repetition rate of 50MH. The rotational probe is based on double cladding photonic crystal fiber (CD PCF) fiber, Grin lens , microprism and rotational MEMS motor.

Imaging skin tissue in vivo with video-rate two-photon autofluorescence microscopy
Paper 7183-48 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 9:25 AM – 9:45 AM

Author(s): Chunqiang Li, Massachusetts General Hospital (United States); Costas M. Pitsillides, Boston Univ. (United States) and Massachusetts General Hospital (United States); Judith M. Runnels, Dana-Farber Cancer Institute (United States) and Massachusetts General Hospital (United States); Mehron Puoris’haag M.D., Massachusetts General Hospital (United States); Daniel Côté, Univ. Laval Robert-Giffard (Canada); Charles P. Lin, Massachusetts General Hospital (United States)

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We report in vivo mouse skin imaging with two-photon fluorescence microscopy by using endogenous tryptophan as the fluorophore. With a femtosecond laser at 600 nm wavelength as the excitation source we obtain non-invasive images of skin tissue at video-rate which provide structural information on skin components such as epidermal cells, hair follicles, fibroblast cells. Comparing with in vivo NADH fluorescence imaging, this new method provides epidermal cells and fibroblasts images with better cell morphology. We also obtain images of blood vessels and muscle cells with this method.

Generation of nanostructured surfaces by interfering and no-interfering ultra-short pulse laser processing
Paper 7201-50 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Yoshiki Nakata, Takuya Hiromoto, Noriaki Miyanaga, Osaka Univ. (Japan)

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Top down technology of ultra-short pulse laser processing was applied to induce liquidly process and generate new nanostructures such as nano-waterdrop, nanocrown, and nano-web structure. For example, a nano-waterdrop was generated by a single shot ps laser irradiation and had the narrow dieter of about 50 nm. In the case of nanocrown, whiskers were standing at the edge of a nanohole, and the diameter of the whiskers was around 100 nm. In addition, nano-sized web like structure was generated in a single shot of femtosecond laser irradiation.

Ultrafast response of negative-index metamaterials in the near infrared
Paper 7205-30 of Conference 7205
Date: Wednesday, 28 January 2009
Time: 11:20 AM – 11:40 AM

Author(s): David J. Cho, Feng Wang, Xiang Zhang, Yuen-Ron Shen, Univ. of California, Berkeley (United States); Wei Wu, Ekaterina Ponizovskaya, Hewlett-Packard Labs. (United States); Pratik Chaturvedi, Univ. of Illinois at Urbana-Champaign (United States); Alexander M. Bratkovksy, Shih-Yuan Wang, Hewlett-Packard Labs. (United States)

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Nanoimprint lithography is used to fabricate a metamaterial with the “fishnet” structure composed of Ag/α-Si/Ag layers that exhibits negative refractive index in the near-infrared. We have carried out a femtosecond pump-probe experiment to measure the transient photo-induced response of this structure. With a pump fluence of 330uJ/cm2 at 800 nm, the transmission at the magnetic resonance is increased by ~15.4%. The induced change originated from carrier excitation in the α-Si layer has a fast decay constant of 1.1ps.

The nonlinear coefficient d36 of CdSiP2
Paper 7197-21 of Conference 7197
Date: Wednesday, 28 January 2009
Time: 2:00 PM – 2:20 PM

Author(s): Valentin P. Petrov, Frank Noack, Ivaylo Tunchev, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany); Peter G. Schunemann, Kevin Zawilski, BAE Systems (United States)

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The new nonlinear crystal for the mid-IR CdSiP2 was discovered only very recently but the interest in this chalcopyrite is enormous because it possesses most of the attractive properties of the related ZnGeP2 but allows in addition pumping at 1064 nm without two-photon absorption and uncritical phase-matching for 6 µm generation with maximized effective nonlinearity. We measured its nonlinear coefficient using SHG near 4.6 µm and femtosecond pulses generated from a seeded KNbO3 optical parametric amplifier. The result, d36( CdSiP2) ˜d36(ZnGeP2), is rather unexpected having in mind the larger band-gap of CdSiP2.

Stochastic models of exciton dynamics in a 5-μm long single air-suspended single-walled carbon nanotube (SWCNT)
Paper 7201-37 of Conference 7201
Date: Wednesday, 28 January 2009
Time: 4:40 PM – 5:00 PM

Author(s): Yee-fang Xiao, Tam Nhan, Mark Wilson, James Fraser, Queen's Univ. (Canada)

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To avoid ensemble heterogeneities and environmental effects, we optically excite and monitor a single air-suspended SWCNT (typical length 5 μm) to resolve its fundamental optoelectronic parameters such as absorption cross section, quantum efficiency and exciton lifetime. We assume the laser pulses stochastically create different numbers of excitons that follow a Poissonian distribution. The probability of having N excitons in a SWCNT decays by both linear and nonlinear processes. We compare different models of nonlinear exciton relaxation with and without exciton diffusion to the experimental results from the femtosecond excitation correlation studies.

Terahertz Wave Technology and Applications
Date: Wednesday, 28 January 2009
Time: 8:30 AM – 12:30 PM

Author(s): Xi-Cheng Zhang, Rensselaer Polytechnic Institute (United States)

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Nanoplasmonics
Date: Thursday, 29 January 2009
Time: 8:30 AM – 5:30 PM

Author(s): Mark I. Stockman, Georgia State Univ. (United States)

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Medical multiphoton microscopic endoscopes and diagnostics
Paper 7183-3 of Conference 7183
Date: Sunday, 25 January 2009
Time: 9:20 AM – 9:45 AM

Author(s): Watt W. Webb, Hyungsik Lim, Chris Xu, Cornell Univ. (United States)

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The intrinsic tissue fluorescence and second harmonic generation (SHG) excited by femtosecond infrared pulse trains from mode-locked lasers provides laser scanning microscopy images of intrinsic fluorescence that are widely applied in biophysical and biomedical research. This capability can now be adapted for Multiphoton Microscopic imaging (MPM) of human tissue in vivo via Medical Multiphoton Microscopic Endoscopes (M-MPM-E) designed to fit anatomical limitations for various medical surgery specialties. The intrinsic MPM imaging capabilities illustrate their applicability for identification and diagnostics of malignancy. The optical design of a flexible 5mm diameter M-MPM-Endoscope applies to internal organs, such as bladder through the urethra.

Carrier dynamics and photoexcited emission efficiency of ZnO:Zn phosphor powders
Paper 7214-4 of Conference 7214
Date: Sunday, 25 January 2009
Time: 9:24 AM – 9:52 AM

Author(s): John V. Foreman, Henry O. Everitt, U.S. Army Aviation and Missile Research, Development and Engineering Ctr. (United States) and Duke Univ. (United States); Jianqiu Yang, Jie Liu, Duke Univ. (United States)

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Nonstoichiometric ZnO with an excess of Zn atoms (ZnO:Zn) has a history of use as a green/monochrome phosphor in electron-excited applications. The advent of ultraviolet lasers and light emitting diodes presents the possibility of photoexciting the highly efficient green emission in ZnO:Zn. Here we study experimentally the time-integrated quantum efficiency and the photoluminescence decays of both band edge and defect emission in ZnO:Zn nano-powders under femtosecond pulsed excitation. A comparison of results using one-photon versus two-photon excitation elucidates how the quantum efficiencies depend on material properties, such as the spatial distribution of defects, and on optical effects, such as reabsorption.

Two-photon luminescence imaging of molecularly-targeted gold nanoparticles using a miniaturized imaging and microsurgery probe
Paper 7183-102 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Christopher L. Hoy, Nicholas J. Durr, The Univ. of Texas at Austin (United States); Wibool Piyawattanametha, Hyejun Ra, Olav D. Solgaard, Stanford Univ. (United States); Adela Ben-Yakar, The Univ. of Texas at Austin (United States)

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Two-photon luminescence (TPL) from gold nanoparticles presents a bright source of contrast for multiphoton microscopy. To better exploit this technique clinically, molecularly-targeted TPL imaging can be conducted through a miniaturized two-photon microscopy probe. Furthermore, the addition of cellular-level microsurgery capabilities presents the potential for a novel “seek-and-treat” tool capable of diagnosing pathologies such as cancer at the cellular level and non-thermally ablating diseased cells while leaving neighboring cells intact. Here, we present TPL imaging of molecularly-targeted gold nanoparticles through a miniaturized optical probe capable of two-photon microscopy as well as femtosecond laser microsurgery.

Label-free biochemical imaging of arterial tissues using photonic crystal fiber (PCF) based nonlinear optical microscopic system
Paper 7182-3 of Conference 7182
Date: Monday, 26 January 2009
Time: 8:40 AM – 9:00 AM

Author(s): Alex Chun-Te Ko, Andrew Ridsdale, Adrian F. Pegoraro, Michael S. D. Smith, Bernie J. Schattka, Mark D. Hewko, Albert Stolow, Michael G. Sowa, National Research Council Canada (Canada)

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Nonlinear optics provides a minimally invasive optical method for fast molecular imaging in highly scattering biological tissues at subcellular resolution. Simultaneous elastin/collagen/lipid imaging of arterial tissues using TPEF, SHG and CARS are achieved using a photonic crystal fiber (PCF) based laser-scanning microscope with single femtosecond laser. This study compares the elastin/collagen structure and lipids distribution on aortic tissue sections obtained from coronary atherosclerosis-prone WHHL-MI rabbits sacrificed at different ages, which mimic spontaneous myocardial infarction in humans. Arterial tissues obtained from nitric oxide synthase knockout mice are also imaged to study the effect of nitric oxide to hypertrophy and fibrosis of left ventricular.

Four-dimensional visualization of ultrafast nuclear motion by electron diffraction
Paper 7214-21 of Conference 7214
Date: Monday, 26 January 2009
Time: 9:24 AM – 9:52 AM

Author(s): Peter N. Baum, Ludwig-Maximilians-Univ. München (Germany) and California Institute of Technology (United States)

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Dynamical changes in condensed matter and molecules involve motion of atoms and electrons from initial to final conformations. To observe such rearrangements in space and time, picometer resolution and femtosecond timing are required. Ultrashort electron pulses, because of their short De Broglie wavelength, allow to directly visualize atomic-scale motions in all four dimensions. Recent results on solid-to-solid phase transformations in vanadium dioxide and ultrafast laser ablation of graphite will be discussed, and concepts for the generation of free attosecond electron pulses will be presented, in order to eventually reach the time scale of electron motions with ultrafast diffraction.

Self imaging in segmented waveguide arrays
Paper 7203-17 of Conference 7203
Date: Monday, 26 January 2009
Time: 10:50 AM – 11:10 AM

Author(s): Matthias Heinrich, Alexander Szameit, Felix Dreisow, Friedrich-Schiller-Univ. Jena (Germany); Frederic Louradour, Eric Suran, XLIM Institut de Recherche (France); Thomas Pertsch, Stefan Nolte, Friedrich-Schiller-Univ. Jena (Germany); Alain Bathelemy, XLIM Institut de Recherche (France); Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)

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Self-imaging in integrated optical devices is interesting for many applications. However, in general this relies on boundary-free light propagation, since the interaction with the boundaries results in a considerable distortion of the self-imaging effect. In this presentation we demonstrate the first experimental realization of particularly segmented waveguide arrays, in which perfect self-imaging is obtained in finite one-dimensional as well as in a two-dimensional geometries. For the fabrication of the segmented waveguide arrays we used the femtosecond direct-writing technique. We believe that such segmented integrated optical devices provide a new and attractive opportunity for image transmission even in finite systems.

Hot phonons in InN-contained heterostructure 2DEG channels
Paper 7216-7 of Conference 7216
Date: Monday, 26 January 2009
Time: 11:00 AM – 11:25 AM

Author(s): Arvydas Matulionis, Puslaidininkiu Fizikos Institutas (Lithuania); Hadis Morkoç, Virginia Commonwealth Univ. (United States)

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The experimental attempts in controlling the LO-phonon lifetime in a 2DEG channel of interest for a nitride HFET will be reviewed. Since the traditional subpicosecond pump–probe Raman scattering is very difficult to employ on a single voltage-biased 2DEG channel, another technique, based on fluctuations, was proposed and implemented. The pioneering results on the lifetime for AlGaN/GaN 2DEG channel were confirmed by femtosecond laser pump-probe hot-LO-phonon-assisted intersubband far-infrared absorption experiments. The fluctuation technique is a very convenient experimental approach to study the phonon lifetime as a function of hot-phonon temperature in a voltage-biased 2DEG channel. The technique in action will be illustrated on InN-contained heterostructure 2DEG channels.

Self-channeled laser pulse induced effects at distance
Paper 7196-11 of Conference 7196
Date: Monday, 26 January 2009
Time: 2:00 PM – 2:20 PM

Author(s): Robert Bernath, Martin C. Richardson, College of Optics & Photonics/Univ. of Central Florida (United States)

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Studies were performed using self-channeled femtosecond laser pulses (filaments) interacting with various materials at a distance of 30 meters. Using time resolved optical shadowgraphy, the filament interaction with the target is observed. Shockwaves in both the target and the surrounding atmosphere are observed and their velocities measured. Estimations of the shockwave energy are made from these observations. In transparent targets, optical coupling into the target material is observed. This coupling results in optical damage lines in the material. Results of the filament interactions will be discussed along with supporting modeling.

Nanosecond laser-induced low-density plasmas: a new regime for nanomorphing in bulk dielectrics
Paper 7203-25 of Conference 7203
Date: Monday, 26 January 2009
Time: 3:00 PM – 3:20 PM

Author(s): Alfred Vogel, Norbert Linz, Sebastian Freidank, Joachim Noack, Univ. zu Lübeck (Germany)

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We compared ns breakdown in water at large NA using single-longitudinal mode and regular Nd:YAG laser pulses. For UV and VIS pulses with a smooth pulse shape (including those from a microchip laser) we discovered a low-density plasma regime in which nano-bubbles are created, with sizes similar to femtosecond breakdown. 3-30 times above the bubble threshold, the plasma suddenly assumes a larger size, luminesces brightly, and larger bubbles of 200 µm radius are produced. Nanoeffects could not be produced with regular pulses, and at IR wavelengths. The two-step process was successfully modeled considering thermal ionization besides multiphoton and avalanche processes.

A new light source for multimodal multi photon microscopy including CARS
Paper 7183-39 of Conference 7183
Date: Monday, 26 January 2009
Time: 4:20 PM – 4:35 PM

Author(s): Ingo Rimke, APE GmbH (Germany); Raluca Niesner, Max-Delbrück-Ctr. für Molekulare Medizin Berlin-Buch (Germany); Edlef Büttner, Gero Stibenz, APE GmbH (Germany)

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We will present a new flexible laser source for multimodal MPE microscopy including CARS. It does consist of a tuneable femtosecond-Ti:Sapphire laser and an optical parametric oscillator (OPO). The new OPO-design allows for high flexibility in pump- and output wavelengths giving rise to for instance image EGFP with the Ti:Sapphire and tdRFP with the OPO simultaneously.
The minimum energy difference between Ti:Sapphire and OPO-wavelengths achievable is 2500cm-1. Thus CARS imaging of lipids is possible. Due to synchronous pumping of the OPO there is no timing jitter between the pulses from the Ti:Sapphire and OPO, absolutely necessary for the time overlap of pump and stokes pulses.

Two-photon imaging and nanoprocessing of stem cells with sub-20 fs laser pulses
Paper 7183-45 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 8:25 AM – 8:45 AM

Author(s): Aisada A. Uchugonova, Fraunhofer-Institut für Biomedizinische Technik (Germany) and Saarland Univ. (Germany); Andreas Isemann, Femtolasers Produktions GmbH (Austria); Rainer Bückle, JenLab GmbH (Germany); Wataru Watanabe, National Institute of Advanced Industrial Science and Technology (Japan); Karsten König, Saarland Univ. (Germany) and JenLab GmbH (Germany)

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Novel ultracompact multiphoton sub-20 femtosecond near infrared 85 MHz laser scanning microscopes and conventional 250 fs laser microscopes have been used to perform high resolution multi-photon imaging of stem cell clusters as well as targeted intracellular nanoprocessing and knock-out of living single stem cells within an 3D microenvironment. Also lethal exposure of large parts of cell clusters was successfully probed while maintaining single cells of interest alive. Mean powers in the milliwatt range for 3D nanoprocessing and microwatt powers for two-photon imaging were found to be sufficient. Ultracompact low power sub-20 fs laser systems may become interesting tools for nanobiotechnology such as optical cleaning of stem cell clusters and optical transfection

Plasmonic perforation of living cells using ultrashort laser pulses and gold nanoparticles
Paper 7192-29 of Conference 7192
Date: Tuesday, 27 January 2009
Time: 11:30 AM – 11:50 AM

Author(s): Markus Schomaker, Judith Baumgart, Laser Zentrum Hannover e.V. (Germany); Hugo Murua Escobar, Univ. of Veterinary Medicine Hannover (Germany); Jörn Bullerdiek, Univ. Bremen (Germany); Ingo Nolte, Univ. of Veterinary Medicine Hannover (Germany); Anaclet Ngezahayo, Leibniz Univ. Hannover (Germany); Holger Lubatschowski, Alexander Heisterkamp, Laser Zentrum Hannover e.V. (Germany)

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If nanoparticles are illuminated with suitable laser light plasmonic resonances can occur. Are these particles placed very close to a cell, the cell membrane gets perforated due to the induced plasmonic effect. We investigate plasmonic perforation of the cell membrane as an alternative technique for cell transfection. By using weakly focussed femtosecond laser pulses, plasmonic resonances were stimulated in 150 nm gold particles. GFSHR-17 rat cells were successfully transfected with a GFP vector and the dependence on laser parameters and concentrations were studied. This technique allows the transfection of cells by opto-perforation without the need of tight focusing conditions.

Three-dimensional photonic devices fabricated by ultrafast lasers for optical sensing in lab-on-a-chip
Paper 7201-35 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Rebeca Martinez Vazquez, Roberto Osellame, Politecnico di Milano (Italy); Chaitanya Dongre, Hugo J. Hoekstra, Markus Pollnau, Univ. Twente (Netherlands); Hans H. van den Vlekkert, Lionix BV (Netherlands); Rob van Weeghel, Zebra Bioscience B.V. (Netherlands); Paul Watts, The Univ. of Hull (United Kingdom); Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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A lab-on-a-chip (LOC) is a device that incorporates in a single substrate the functionalities of a biological laboratory with micrometer dimensions. The next technological challenge of LOCs is direct on-chip integration of photonic functionalities. Ultrafast laser processing of the bulk of a dielectric material is a very flexible and simple method to produce photonic devices inside microfluidic chips for capillary electrophoresis (CE) or chemical microreactors. In this work we report on the use of femtosecond laser pulses to fabricate photonic devices inside commercial CE chips. The fabrication of single waveguides intersecting the channels allows one to perform LIF sensing. Waveguide splitters are used for multipoint sensing measurements. Finally, Mach-Zehnder interferometers are used for label-free sensing by means of refractive index changes detection.

Three-dimensional photonic devices fabricated by ultrafast lasers for optical sensing in lab-on-a-chip
Paper 7203-35 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Rebeca Martinez Vazquez, Roberto Osellame, Politecnico di Milano (Italy); Chaitanya Dongre, Hugo J. Hoekstra, Markus Pollnau, Univ. Twente (Netherlands); Hans H. van den Vlekkert, Lionix BV (Netherlands); Rob van Weeghel, Zebra Bioscience B.V. (Netherlands); Paul Watts, The Univ. of Hull (United Kingdom); Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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A lab-on-a-chip (LOC) is a device that incorporates in a single substrate the functionalities of a biological laboratory with micrometer dimensions. The next technological challenge of LOCs is direct on-chip integration of photonic functionalities. Ultrafast laser processing of the bulk of a dielectric material is a very flexible and simple method to produce photonic devices inside microfluidic chips for capillary electrophoresis (CE) or chemical microreactors. In this work we report on the use of femtosecond laser pulses to fabricate photonic devices inside commercial CE chips. The fabrication of single waveguides intersecting the channels allows one to perform LIF sensing. Waveguide splitters are used for multipoint sensing measurements. Finally, Mach-Zehnder interferometers are used for label-free sensing by means of refractive index changes detection.

5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7201-38 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7203-38 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

Integration of micro-optics and microfluidics in a glass chip by fs-laser for opto-fluidic applications
Paper 7202-1 of Conference 7202
Date: Wednesday, 28 January 2009
Time: 8:20 AM – 8:50 AM

Author(s): Roberto Osellame, Rebeca Martinez Vazquez, Paolo Laporta, Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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The combination of microoptics and microfluidics, also known as optofluidics, is raising an increasing interest. Recently, directly buried high quality waveguides and microfluidic channels have been fabricated by femtosecond lasers. The main advantage of this technique is its three-dimensional capability providing high flexibility in intersecting the optical and fluidic structures.
In this work, a few optofluidic devices based on this technology will be discussed. On one hand, the integration of an ultrafast optical switch is demonstrated. On the other hand, the integration of optical waveguides and Mach-Zehnder interferometers for sensing of biomolecules in a capillary electrophoresis chip will be presented.

Time-resolved photoluminescence characterization on the two-photon pumped stimulation emission in ZnO nanowires
Paper 7214-55 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 1:48 PM – 2:16 PM

Author(s): Jian Xu, Chunfeng Zhang, Fan Zhang, Ting Zhu, The Pennsylvania State Univ. (United States)

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We report in this conference our effort to investigate the mechanism of two-photon absorption-induced stimulation emission in ZnO nanowires. Time-resolved photoluminescence (TRPL) measurement was performed to study the transient decays of ZnO nanowire-emission following the femtosecond pulse excitation (τ~80fs, λ~700nm) with the fluence energy varied below and above the threshold (160µJ/cm2), respectively. A very fast decay with lifetime 3-4 ps was measured, suggesting by analogy with the one-photon absorption-induced process that the faster component can be assigned to the two-photon absorption-induced stimulated emission originating from a many-particle effect-associated recombination mechanism.

Two-photon photocurrent spectroscopy of quantum well intersubband relaxation and dephasing
Paper 7214-56 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 2:16 PM – 2:44 PM

Author(s): Harald Schneider, Forschungszentrum Dresden-Rossendorf e. V. (Germany); Hui Chun Liu, National Research Council Canada (Canada); Thomas Maier, Martin Walther, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)

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We have studied electron intersubband relaxation and dephasing times in n-type InGaAs/AlGaAs quantum wells by femtosecond two-photon photocurrent spectroscopy. The approach enables us to determine systematically the dependence of these time constants on structural parameters, including carrier density and modulation/well doping, and to discriminate between different scattering processes. By varying the excitation energy, we also tuned the two-photon transition from resonant, yielding optimum resonant enhancement with a real intermediate state, to nearly-resonant, with a virtual but resonantly enhanced intermediate state. For autocorrelation purposes, the latter configuration improves time resolution whilst partially retaining a resonant enhancement of the two-photon transition strength.

Light-matter interaction processes behind intracavity mode-locking devices
Paper 7193-67 of Conference 7193
Date: Wednesday, 28 January 2009
Time: 2:50 PM – 3:10 PM

Author(s): Narasimha S. Prasad, NASA Langley Research Ctr. (United States); Chandra Roychoudhuri, Univ. of Connecticut (United States)

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We believe that the lasing medium runs in a single mode (frequency) at the center of the gain medium and the intra-cavity saturable absorber or the Kerr medium simply plays the role of fast time gating (switching). This implies that “transform limited” “mode-locked” laser pulses, in reality, contain only a single carrier frequency. We will present the appropriate mathematical representation for the spectral analysis of such “mode-locked” pulses. We will also discuss models for the physical process that give rise to the generation of short (nanosecond class) pulses even in the absence of multiple longitudinal modes and then use the concepts for generating shorter (picoseconds and femtosecond) pulses.

Dynamic ultrafast laser beam tailoring for multispot photo-inscription of deep photonic devices in bulk transparent materials
Paper 7205-37 of Conference 7205
Date: Wednesday, 28 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Cyril Mauclair, Guanghua Cheng, Nicolas Huot, Eric Audouard, Lab. Hubert Curien (France); Arkadi Rosenfeld, Ingolf V. Hertel, Max-Born-Institut (Germany); Razvan I. Stoian, Lab. Hubert Curien (France)

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Femtosecond laser processing in transparent media can generate localized increase of the refractive index. Thus, by simple translation of the laser spot, light-guiding structures are achievable in the three dimensions. We report in the following a procedure of dynamic ultrafast laser beam tailoring for parallel photo inscription of deep photonic devices in a-SiO2. The wave front of the beam is controlled to achieve multi spot operation with real time adjustable separation of the spots. The procedure involves the control of the spatial phase of the beam with a spatial light modulator and is based on imaging of the laser spots.

Quantitative characterization of linear and nonlinear absorption of fluorescent proteins
Paper 7213-26 of Conference 7213
Date: Wednesday, 28 January 2009
Time: 4:20 PM – 4:40 PM

Author(s): Mikhail A. Drobizhev, Shane Tillo, Nikolay S. Makarov, Thomas E. Hughes, Aleksander K. Rebane, Montana State Univ., Bozeman (United States)

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We propose a pure optical method of evaluation of mature Fluorescent Protein extinction coefficient by using Strickler - Berg equation, which relates fluorescence radiative lifetime and molecular extinction coefficient. Using this approach we evaluated fluorescence lifetimes, quantum efficiencies, and extinction coefficients of a large number of FPs, including GFP, EGFP, CFP, DsRed2, mRFP, tagRFP, and mFruits series.
We also obtained accurate 2PA spectra of these proteins in the broad range, 700 - 1200 nm, using our computer-controlled femtosecond 2PA spectrometer. This information allows for quantitative comparison and selection of the one- and two-photon brightest FP mutants at any selected wavelength.

Multifocal multimodal multiphoton photon counting imaging
Paper 7184-20 of Conference 7184
Date: Wednesday, 28 January 2009
Time: 5:10 PM – 5:30 PM

Author(s): Ramon Carriles, Jeffrey Field, Erich E. Hoover, Kraig E. Sheetz, Jeffrey A. Squier, Colorado School of Mines (United States)

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We have developed a novel femtosecond laser and photon detection system that, when coupled together, enables multifocal, multiphoton imaging through scattering media with single element detectors for the first time. For example, to date we have been able to image six different image areas in a single modality (e.g., two-photon absorption fluorescence imaging, second harmonic generation imaging, or third harmonic generation imaging) simultaneously, using a single photomultiplier tube. Some novel features of this imaging system, demonstrated to date include, the ability to perform multiphoton imaging at different polarizations simultaneously, image different depths simultaneously, and measure-bleaching rates for various excitation pulse shapes for fluorescently labeled systems.

Self-phase-locked divide-by-2 sync-pumped optical parametric oscillator as a broadband frequency comb source
Paper 7197-34 of Conference 7197
Date: Thursday, 29 January 2009
Time: 9:00 AM – 9:20 AM

Author(s): Samuel T. Wong, Tomas Plettner, Konstantin L. Vodopyanov, Robert L. Byer, Stanford Univ. (United States)

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We demonstrate simultaneous transposing and broadening the range of a frequency comb source by using a divide-by-2 subharmonic generator based on degenerate synchronously-pumped femtosecond optical parametric oscillator (SPOPO). We used a type I phase-matched PPLN crystal as a nonlinear gain element and a mode-locked Ti:sapphire laser at 775 nm as a pump. At degeneracy (around 1550 nm), the spectrum width of our linear-cavity SPOPO was 210 cm-1, which is 2.6 times broader than that of the pump, and produced transform-limited 70-fs output pulses. The SPOPO exhibited self-phase-locking between the signal, idler comb modes, and the modes of the pump.

Integration of photonic crystal fibres and MEMS for nonlinear optical endoscopy
Paper 7219-14 of Conference 7219
Date: Thursday, 29 January 2009
Time: 11:00 AM – 11:30 AM

Author(s): Min Gu, Swinburne Univ. of Technology (Australia)

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In this presentation, I will give a review on our recent progress on the development of nonlinear optical endoscopy with the integration of photonic crystal fibres and MEMS. Endoscopy is the preeminent technique for minimally invasive cancer diagnosis and monitoring in vivo. The combination of endoscopy with nonlinear optical microscopy is a catalyst for the rapid point of care application of today’s cutting edge biology by health practitioners. We present multiphoton nonlinear tissue imaging from an endoscope probe held static with respect to the tissue region of interest. Femtosecond pulsed excitation is delivered within the double clad photonic crystal fibre core, through the endoscope probe head by microelectromechanical system (MEMS) scanning mirror and focused into the tissue sample by gradient index (GRIN) lens. The feasibility of using a supercontinuum source from a nonlinear photonic crystal fibre will be discussed.

Ultrafast parametric oscillators for spectroscopy
Paper 7193-84 of Conference 7193
Date: Thursday, 29 January 2009
Time: 1:20 PM – 1:50 PM

Author(s): Derryck T. Reid, Lukasz W. Kornaszewski, T. P. Mueller, Nicolas Gayraud, William N. MacPherson, Duncan P. Hand, James M. Stone, Jonathan C. Knight, Heriot-Watt Univ. (United Kingdom)

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The high spatial coherence, wide tunability and broad intrinsic bandwidth of femtosecond optical parametric oscillators makes them uniquely attractive sources for spectroscopy in the visible and infrared. Using systems based on MgO:PPLN, and pumped by a self-modelocked Ti:sapphire laser, we have shown free-space and photonic-crystal-fibre-based spectroscopy of methane to concentrations as low as 50 ppm. New diode-pumped solid-state ultrafast lasers are now able to exceed the performance of Ti:sapphire lasers and we will describe performance obtained using a Yb:fibre-pumped OPO that so far has produced 20 nJ pulses directly from the oscillator, with the potential for energy scaling to ~1 µJ levels.


Multiphoton Microscopy (MM) - Basics, Technology Development, and Applications
Date: Saturday, 24 January 2009
Time: 8:30 AM – 5:30 PM

Author(s): Ammasi Periasamy, Univ. of Virginia (United States); Peter T. C. So, Massachusetts Institute of Technology (United States)

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Multispectral multiphoton lifetime analysis of human bladder tissue
Paper 7161B-205 of Conference 7161B
Date: Saturday, 24 January 2009
Time: 9:50 AM – 10:10 AM

Author(s): Riccardo Cicchi, Alfonso Crisci, Gabriella Nesi, Alessandro Cosci, Marco Carini, Francesco S. Pavone, Univ. degli Studi di Firenze (Italy)

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Human tissues intrinsically contains many fluorophores that can be excited and imaged using multiphoton microscopy. In this work we used combined two photon intrinsic fluorescence (TPE), second harmonic generation microscopy (SHG), fluorescence lifetime imaging microscopy (FLIM), and multispectral two photon emission detection (MTPE) to investigate different kinds of human ex-vivo fresh biopsies of bladder. Morphological and spectroscopic analyses allowed to characterize both healthy and pathological tissue samples in a good agreement with common routine histology. Our method is a promising tool to be used as a diagnostic tool in a multiphoton endoscope or cystoscope.

Human bladder cancer diagnosis using multiphoton microscopy
Paper 7161B-206 of Conference 7161B
Date: Saturday, 24 January 2009
Time: 10:40 AM – 11:00 AM

Author(s): Sushmita Mukherjee, James S. Wysock, Casey K. Ng, Mohammed Akhtar, Sven Perner, Ming-Ming Lee, Mark A. Rubin, Frederick R. Maxfield, Weill Cornell Medical College (United States); Watt W. Webb, Cornell Univ. (United States); Douglass S. Scherr, Weill Cornell Medical College (United States)

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Approximately 75% of bladder cancers present as non-muscle invasive, at which stage they can be treated completely. However, these lesions, being small and flat, are often hard to detect with conventional cystoscopes. These cystoscopes also fail to assess resection margins for negativity. Thus, a Multiphoton endoscope, with high magnification and resolution, is currently being built at Cornell University, Ithaca. Here, we present evidence that images of diagnostic quality can be obtained from fresh, unstained human bladder specimens (biopsies and whole excised bladders) using a custom assembled bench-top Multiphoton microscope. All Multiphoton diagnoses are compared with gold standard Hematoxyin/eosin histopathology.

In vivo multiphoton tomography in skin aging studies
Paper 7161A-116 of Conference 7161A
Date: Saturday, 24 January 2009
Time: 2:15 PM – 2:30 PM

Author(s): Karsten König, JenLab GmbH (Germany)

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Multiphoton tomography based on high resolution optical sectioning of the epidermis and the upper dermis has been used to analyze the morphology of the epidermal-dermal junction as well as the ratio of elastin to collagen (SAAID index).
The signal of elastin and intracellular endogenous fluorophores was obtained by two-photon excitation whereas collagen structures were imaged by the detection of second harmonic generation (SHG).
The in vivo measurements on volunteers were performed with the novel multiphoton tissue tomograph based on a compact femtosecond near infrared laser system and a flexible scan and detector head.

Medical multiphoton microscopic endoscopes and diagnostics
Paper 7183-3 of Conference 7183
Date: Sunday, 25 January 2009
Time: 9:20 AM – 9:45 AM

Author(s): Watt W. Webb, Hyungsik Lim, Chris Xu, Cornell Univ. (United States)

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The intrinsic tissue fluorescence and second harmonic generation (SHG) excited by femtosecond infrared pulse trains from mode-locked lasers provides laser scanning microscopy images of intrinsic fluorescence that are widely applied in biophysical and biomedical research. This capability can now be adapted for Multiphoton Microscopic imaging (MPM) of human tissue in vivo via Medical Multiphoton Microscopic Endoscopes (M-MPM-E) designed to fit anatomical limitations for various medical surgery specialties. The intrinsic MPM imaging capabilities illustrate their applicability for identification and diagnostics of malignancy. The optical design of a flexible 5mm diameter M-MPM-Endoscope applies to internal organs, such as bladder through the urethra.

Evaluating thermal damage induced by pulsed light with multiphoton microscopy
Paper 7161A-132 of Conference 7161A
Date: Sunday, 25 January 2009
Time: 11:00 AM – 11:15 AM

Author(s): Wei Gong, Yimei Huang, Hui Li, Shusen Xie, Fujian Normal Univ. (China)

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Nonablative skin light treatment tend to be a promising method to treat photoaged skin. Various kind of laser and irradiated parameters had been used to implement this process. Determining the extent of thermal damage to skin has important meanings in nonablative skin light treatment. We attempt to evaluate the thermal damage of skin induced by pulsed light using multiphoton fluorescence and second-harmonic-generation (SHG) microscopy. The results show the intensity of multiphoton and SHG of thermal damaged upper dermis varied with the irradiated light dose, and could be a potential in-vivo imaging method to evaluate the treatment efficacy of nonablative skin light treatment.

Multiphoton fluorescence microscopy using compact femtosecond fiber laser
Paper 7203-7 of Conference 7203
Date: Sunday, 25 January 2009
Time: 11:20 AM – 11:40 AM

Author(s): Cheryl Zhan, Chulmin Joo, Siavash Yazdanfar, GE Global Research (United States); Mikhail Berezin, Sam Achilefu, Washington Univ. in St. Louis School of Medicine (United States)

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We developed a new MPM imaging system operating in the spectral window around 1550 nm, which features the optimal balance between scattering and absorption, and minimized the contribution of autofluorescence. This NIR window coincides with the primary telecommunications window, resulting in a plethora of available light sources including compact, turnkey femtosecond fiber lasers. The fluorescence emission is in the NIR wavelengths, which extends the penetration depth.

We synthesized new carbocyanine NIR fluorescent probes optimized at this particular window, and measured their two-photon fluorescence intensity and lifetime with time-correlated single photon counting.

Multi-spectral multiphoton NDD FLIM
Paper 7183-10 of Conference 7183
Date: Sunday, 25 January 2009
Time: 1:25 PM – 1:45 PM

Author(s): Klaus Weisshart, Carl Zeiss Jena GmbH (Germany); Wolfgang Becker, Becker & Hickl GmbH (Germany)

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Research on the mechanisms of tumor genesis, Alzheimer disease, and other metabolic disorders has resulted in an increasing demand for advanced in-vivo imaging techniques. Multiphoton excitation with non-descanned detection (NDD) is required to reach deep tissue layers within a live specimen. Multi-spectral detection is needed to discriminate fluorescence from the various fluorophores present in biological tissue. Moreover, many endogenous fluorophores appear in different binding states or conformations with identical spectra but different fluorescence lifetimes. Although solutions to these individual problems are commonly available there is currently no system that allows the user to simultaneously use multiphoton excitation, NDD detection, multi-spectral detection, and FLIM. We have therefore developed a multi-spectral FLIM system for the non-descanned ports of the Zeiss LSM 710 NLO and LSM 510 NLO multiphoton microscopes. The system uses multi-dimensional TCSPC. Every photons is characterised by its time in the pulse period of the excitation laser, its wavelength, and its coordinates in the sample. The recording process builds up the distribution of the photon number over these parameters. Thus, FLIM images in up to 16 wavelength channels are obtained simultaneously and at near-ideal efficiency. We demonstrate the capabilities of the system for autofluorescence of tissue.

Multiphoton absorption and nonlinear optical phenomena in semiconductor nanocrystals
Paper 7214-12 of Conference 7214
Date: Sunday, 25 January 2009
Time: 2:44 PM – 3:12 PM

Author(s): Gregory D. Scholes, Univ. of Toronto (Canada)

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Semiconductor nanocrystals (or quantum dots) are of interest because of their size and shape tunable properties. Nonlinear optics provides a means of examining in detail the electronic properties as well as dephasing mechanisms characteristic of nanoscale excitons in quantum dots. The results of a number of recent studies will be reported, including two-dimensional electronic spectroscopic studies of CdSe nanocrystals. As one example, recent work reporting the direct observation of a large three-photon resonance in water-soluble ZnS quantum dots will be described.

Deep-tissue multiphoton FLIM for intravital FRET imaging
Paper 7183-117 of Conference 7183
Date: Sunday, 25 January 2009
Time: 5:10 PM – 5:30 PM

Author(s): G. Fruhwirth, Simon M. Ameer-Beg, Melanie D. Keppler, A. Brock, King's College London (United Kingdom); Boris Vojnovic, Gray Cancer Institute (United Kingdom); T. Ng, King's College London (United Kingdom)

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Fluorescent lifetime imaging microscopy (FLIM) has proven to be a valuable tool in beating the Rayleigh criterion for light microscopy by measuring Förster resonance energy transfer (FRET) between two fluorophores. Applying multiphoton FLIM, we previously showed in a human breast cancer cell line that recycling of a membrane receptor-green fluorescent protein fusion is enhanced concomitantly with the formation of a receptor:protein kinase C a complex in the endosomal compartment [Biophys J 88 (2005), 1224]. We have extended this established technique (FRET by FLIM, [Nat Cell Biol 9, (2006), 80 and EMBO J 22, (2003),
5390]) to probe direct protein-protein interactions also in vivo.
Therefore, we used various expressible fluorescent tags fused to membrane receptor molecules in order to generate stable two-colour breast carcinoma cell lines via controlled retroviral infection. We used these cell lines for establishing a xenograft tumour model in immune-compromised Nude mice. Using this animal model in conjunction with scanning Ti:Sapphire laser-based two-photon excitation, we established deep-tissue multiphoton FLIM in vivo. For the first time, this novel technique enables us to directly assess donor fluorescence lifetime changes in vivo and we show the application of this method for intravital imaging of direct protein-protein interactions.

Coherent control in multiphoton fluorescence imaging*
Paper 7183-83 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Arijit Kumar De, Debabrata Goswami, Indian Institute of Technology Kanpur (India)

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Multiphoton fluorescence laser-scanning microscopy has been shown to be superior to its single-photon confocal counterpart in terms of better depth resolution. Often the wide spectral range of the pulsed laser fails to selectively excite fluorophores. In addition, the scarcity of fluorophores with large multiphoton absorption cross-sections severely affects practical application. These two drawbacks can be taken care of by ‘shaping’ the laser pulse to control molecular fluorescence and design of novel chromophores having high absorption cross-sections. Recent works from our group in these illuminating fields will be addressed.

Dispersion control considerations for multiphoton and non-linear laser microscopy applications
Paper 7183-103 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Craig Brideau, Hotchkiss Brain Institute (Canada); Sangeeta Murugkar, Univ. of Ottawa (Canada)

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Considerable debate has recently arisen regarding the necessity for pulse dispersion control for Multiphoton microscopy. At question is whether the degree of improvement achieved by implementing dispersion control justifies the expense of the extra equipment required. In this paper we will address some of the situations under which dispersion control may or may not be desirable. For the former case, we will consider a cost-effective design for a home-built prism compressor system that can be constructed from off-the-shelf parts.

High-resolution adaptive wavefront correction in multiphoton microscopy*
Paper 7183-84 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Gunnsteinn Hall, Min Ren, Kevin Eliceiri, John G. White, Univ. of Wisconsin, Madison (United States)

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A novel approach for adaptive wavefront correction in multiphoton laser scanning microscopy (MPLSM) is proposed. Previously, deformable mirrors have been used to compensate for sample-induced aberrations. However, these devices generally have a limited resolution.
We use a high-resolution liquid crystal spatial light modulator (SLM) as the corrective device, which allows higher-order aberrations to be corrected than can be achieved by typical deformable mirrors. A genetic algorithm determines the optimal phase correction.
Initial results have shown that images can be obtained at greater depths using this system. Work is in progress to optimize the system for use with living biological specimens.

In vivo multiphoton microscopy of neuronal networks in deep cortical layers using a microprism probe*
Paper 7183-92 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Thomas H. Chia, Michael J. Levene, Yale Univ. (United States)

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In vivo cellular imaging of deep brain tissue is limited by its highly light-scattering nature. We present a 1 mm microprism probe capable of imaging multiple cortical layers simultaneously
without significant functional damage to the region of interest. The hypotenuse of the microprism probes have a high-reflectivity coating to translate the x-, y- raster scanning pattern of the laser to a x-, z- scanning pattern. Images were collected with two-photon microscopy from the mouse motor, barrel, and somatosensory cortex and show a wide field-of-view, dendritic spines from layer V neurons, red blood cell flow, and evoked
neuronal calcium activity.

Mechanical properties of tissue determined by multiphoton microscopy*
Paper 7183-75 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Magnus B. Lilledahl, Catharina de Lange Davies, Norwegian Univ. of Science and Technology (Norway)

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The mechanical properties of tissues are in a large part related to the structural proteins collagen and elastin. By imaging these structures one can derieve important information regarding the mechanical properties of tissue, which is important in many medical applications. We have studied the relation between microscopic images of the structural proteins and macroscopic mechanical properties. While imaging collagen with second harmonic generation and elastin with two-photon excited fluorescence and simultaneously measuring the macroscopic mechanical properties we gain insight into the realation between the microscopic structure and macroscopic mechanical properties. We have conducted experiments to investigate the relationship between these two quantities. This information will be used to develop better mechanical models of various tissue organs which are used in characterization of many pathological conditions.

Multiphoton autofluorescence for assessing therapeutic effects of a cox-2 inhibitor in oral carcinogensis
Paper 7183-108 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Ki K. Ho M.D., Tuya Shilagard, Suimin Qiu, Susan McCammon M.D., Massoud Motamedi, Vicente Resto M.D., Gracie Vargas, The Univ. of Texas Medical Branch at Galveston (United States)

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Cyclooxygenase (COX)-2 has been shown to be overexpressed in oral carcinogenesis. In vivo multiphoton autofluorescence was evaluated as a technique for noninvasively detecting effects of celecoxib, a COX-2 inhibitor, in a hamster oral carcinogenesis model.
This longitudinal study compared microscopic morphometric parameters and spectroscopic parameters of buccal epithelium in two groups, a DMBA treated group given a standard diet and a DMBA group receiving a diet containing celecoxib. Statistical analysis was performed to assess differences in the cox-2 inhibited group and the control group. Multiphoton autofluorescence revealed microstructural changes consistent with neoplastic transformation, which were ameliorated in the cox-2 inhibited group.

Multiphoton microscopy as a diagnostic tool for anatomopathological studies of sentinel lymph nodes
Paper 7183-109 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Joel Lemière, Jean-Claude A. Vial, Julien Douady, François Estève, Sylvie Lantuejoul, Philippe Lorimier, Clément Ricard, Dimitri Salameire, Boudewijn P. J. van der Sanden, Univ. Joseph Fourier (France)

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To characterize the malignancy in patients bearing a breast or lung tumor, anatomopathologists realize the microscopy of 3µm thin slices after an extensive preparation of the tissues during several days. In general, only 8 slices per “sentinel” lymph nodes are observed.We show that the anatomopathological study with multiphoton microscopy is faster and easier than the classic technique by imaging the porc lymph nodes with endofluorescence, with permeant dyes and with SHG up to 80µm below the surface. We also image 3 µm slices of human lymph nodes bearing metastatic melanoma cells showing good contrasts between tumor and healthy tissues.

Multiphoton microscopy of near infrared dyes
Paper 7183-110 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Siavash Yazdanfar, Chun Zhan, Chulmin Joo, GE Global Research (United States); Mikhail Berezin, Samuel Achilefu, Washington Univ. in St. Louis School of Medicine (United States)

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We describe multiphoton microscopy using a compact, turnkey femtosecond fiber to excite a new class of near infrared carbocyanine dyes. This system offers advantages in penetration depth, contrast, and simplicity as compared to conventional multiphoton microscopy.

Non-linear effects and role of scattering in multiphoton imaging of thick biological samples*
Paper 7183-74 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Francesca Cella, Zeno Lavagnino, Alberto Diaspro, Univ. degli Studi di Genova (Italy)

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While performing imaging of biological scattering tissues in non linear excitation regime, the localization of the maximum 2PE intensity was found to shift closer to the surface and the 2PE imaging depth limit appears strongly limited by near surface fluorescence. In this work we computed the illumination and the photobleaching distribution in order to characterize the effects induced by scattering. Simulations have been performed for different scattering and an experimental test has been carried out by imaging thick scattering fluorescent immobile samples. Results confirm that under certain conditions no photobleaching effects due to scattering occur close to the surface.

Optimization of fluorescence collection in multiphoton microscopy*
Paper 7183-91 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Joseph Zinter, Michael J. Levene, Yale Univ. (United States)

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Efficient fluorescence collection is critically important to maximize image quality and depth in multiphoton microscopy. Here we present an optimized, large aperture fluorescence collection system for use with the Olympus 20 X 0.95NA objective and two Hamamatsu H7422P-40 GaAsP photomultiplier tubes. Using Zemax optical design software to model the fluorescence intensity distribution and collection geometry, we have designed and constructed an optimized, large aperture detector housing assembly, which provides a significant increase in collected fluorescent signal, image quality, and maximum imaging depth.

Evaluation of diseases in vivo with coherent Raman and multiphoton microscopy
Paper 7183-23 of Conference 7183
Date: Monday, 26 January 2009
Time: 9:20 AM – 9:45 AM

Author(s): Erik Bélanger, Steve Begin, Sophie Laffray, Stephane Pages, Univ. Laval Robert-Giffard (Canada); Réal Vallée, Univ. Laval (Canada); Yves De Koninck, Daniel Côté, Univ. Laval Robert-Giffard (Canada)

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We are studying multiple sclerosis with an animal model called experimental auto-immune encephalomyelitis (EAE). After surgically exposing the spinal cord, we characterize the amount of demyelination using the CARS modality and use reflectance and fluorescence imaging to study the dynamics of axons and other glial cells. We describe the animal model as well as the critical steps to enable live animal imaging (video-rate microscopy, image stabilization). We show a complete characterization of the polarization dependence of the CARS signal in fresh spinal cord tissue, and discuss the resulting non uniformities of the image intensities including a solution based on circular polarizations. Finally, the use of CARS spectroscopy for diagnosis will be discussed.

Coupling CARS with multiphoton fluorescence and harmonic generation on the same platform
Paper 7183-40 of Conference 7183
Date: Monday, 26 January 2009
Time: 4:35 PM – 4:50 PM

Author(s): Hongtao Chen, Haifeng Wang, Jiabin Zhu, Kimberly Buhman, Ji-Xin Cheng D.V.M., Purdue Univ. (United States)

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We present an approach to add the coherent anti-stokes Raman scattering (CARS) imaging modality to a multiphoton microscope. A MaiTai laser and an optical parametric oscillator (OPO) provide the excitation beams. The frequency-doubled idler beam is combined with the MaiTai beam for CARS imaging. The MaiTai beam and the signal beam from OPO are also used for multiphoton fluorescence and second/third harmonic generation imaging, respectively. Internal spectral detectors are employed for microspectroscopy analysis. This system enables multimodal NLO imaging of various components in a biological tissue.

Enhancement of multiphoton excitation-induced photoacoustic signals by using gold nanoparticles surrounded by fluorescent dyes
Paper 7177-83 of Conference 7177
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Yoshihisa Yamaoka, Tetsuro Takamatsu, Kyoto Prefectural Univ. of Medicine (Japan)

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Recently, we have developed multiphoton excitation-induced photoacoustic imaging employing a 1064-nm nanosecond pulsed laser to improve the depth penetration in living tissues. Because the generation of photoacoustic signal induced by multiphoton excitation is less efficient than that by one-photon excitation, it is important to enhance selectively only the signal induced by multiphoton excitation. In this study, we demonstrated the enhancement of multiphoton-photoacoustic signal by using gold nanoparticles surrounded by fluorescent dyes as contrast agents. This enhancement is effected by the wavelength selectivity of fluorescent dyes and the thermal characteristics of gold nanoparticles.

In vivo multiphoton tomography using a high NA GRIN microendoscope
Paper 7183-44 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 8:00 AM – 8:25 AM

Author(s): Karsten König, JenLab GmbH (Germany)

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Multiphoton tomographs based on femtosecond laser and GRIN lens technology in combination with flexible scan heads have been developed for clinical high-resolution tissue imaging and small animal research. The novel multiphoton tissue tomograph possesses an articulated mirror arm in combination with a flexible scan head which includes galvoscanner, a piezodriven focusing optics and a PMT photodetector as well as a rigid GRIN microendoscope. 250 MHz fiber based femtosecond lasers as well as 80 MHz tunable Ti:Sa lasers have been tested as source for two-photon SHG , autofluorescence, and FLIM imaging

Multiphoton ionization and attosecond science inside transparent dielectrics
Paper 7214-35 of Conference 7214
Date: Tuesday, 27 January 2009
Time: 10:20 AM – 11:00 AM

Author(s): Paul B. Corkum, National Research Council Canada (Canada) and Univ. of Ottawa (Canada); Marina Gertsvolf, D. Grojo, National Research Council Canada (Canada); S. Golin, Univ. of Ottawa (Canada); S. Lei, Kansas State Univ. (United States); David M. Rayner, National Research Council Canada (Canada)

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Attosecond processes, similar to those that arise in atomic and molecular gases, must occur in large band-gap dielectrics and in dense gases. However, to observe them we need to develop diagnostic methods that are appropriate for solids. Since even intense short pulses contain very few photons, one approach is to study beam depletion. We discuss how this may lead to attosecond time resolution inside dielectrics...

New developments of systems for multiphoton microscopy
Paper 7183-55 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 11:00 AM – 11:15 AM

Author(s): Eva Simbuerger, Carl Zeiss Jena GmbH (Germany)

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Multiphoton Microscopy has established itself as a widely used technique in biomedical imaging. The original technological hurdles have long been overcome and easy-to-use software-controlled systems have become standard. Future challenges include the adaptation of these systems to a variety of more sophisticated applications using specialized optics coatings or different types of detectors. Technical innovations are directed towards such diverse applications as second harmonic generation, spectral imaging or manipulation with high laser power.

Investigating new sources of femtosecond fiber lasers in multiphoton microscopy
Paper 7183-56 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 11:15 AM – 11:30 AM

Author(s): Shuo Tang, Univ. of British Columbia (Canada) and Univ. of California, Irvine (United States); Jian Liu, PolarOnyx, Inc. (United States); Zhongping Chen, Bruce J. Tromberg, Univ. of California, Irvine (United States)

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Femtosecond fiber lasers have emerged as a promising light source for MPM applications. The laser system is reliable, compact, low-cost, and portable because it uses mostly fiber connected components from telecommunications. We have implemented compact, all-fiber based femtosecond fiber lasers in multiphoton imaging at the wavelength bands of 1030 nm and 1560 nm. Intrinsic second-harmonic generation signal is excited from rat tail tendon and human skin samples. Two-photon excited fluorescence images are obtained from tissues stained with exogenous fluorophores. Our results show that the femtosecond fiber lasers have the great potential of applications in developing all-fiber based, portable multiphoton endoscopes.

Adaptive optics for multiphoton microscopy
Paper 7183-49 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 11:30 AM – 11:45 AM

Author(s): Martin J. Booth, Delphine Debarre, Kate Grieve, Tony Wilson, Univ. of Oxford (United Kingdom)

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Specimen-induced aberrations are frequently encountered in high resolution microscopy, particularly when high numerical aperture lenses are used to image deep into biological specimens. These aberrations distort the focal spot causing a reduction in resolution and, often more importantly, reduced signal level and contrast. This is particularly problematic in multiphoton microscopy, where the non-linear nature of the signal generation process means that the signal level is strongly affected by changes in the focal spot intensity. We have applied the techniques of adaptive optics to correct aberrations in two-photon fluorescence and harmonic generation microscopes, restoring image quality.

Multiphoton microscopy by multiexcitonic ladder climbing in colloidal quantum dots
Paper 7183-50 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 11:45 AM – 12:00 PM

Author(s): Dan Oron, Nir R. Ben Haim, Weizmann Institute of Science (Israel)

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Depth resolved multiphoton microscopy is performed by collecting the fluorescent emission of two-exciton (BX) states in colloidal quantum dots, formed via two sequential resonant absorption events. Due to the large absorption cross-section and the long intermediate state lifetime, unprecedented low excitation energy and peak powers are required to generate this nonlinear response, and the effective two-photon cross section can be as large as ~10^10 GM. The depth resolution of our microscope is shown to be equivalent to a standard two-photon microscope. The system also shows slow saturation due to the contribution of higher excited states to the emitted signal.

Fabrication of tailored photonic crystals using multiphoton lithography
Paper 7223-8 of Conference 7223
Date: Tuesday, 27 January 2009
Time: 3:30 PM – 4:00 PM

Author(s): Joseph W. Perry, Georgia Institute of Technology (United States)

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5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7201-38 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7203-38 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

Multimodal multiphoton microscopy
Paper 7183-65 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:25 PM

Author(s): François Légaré, Institut National de la Recherche Scientifique (Canada); Christian P. Pfeffer M.D., Harvard Medical School (United States); Feruz S. Ganikhanov, West Virginia Univ. (United States)

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Multiphoton microscopy is a powerful technique for high spatial resolution thick tissue imaging. In its simple version, it uses fluorescence. However, not every biological structure is inherently fluorescent or can be stained without causing biochemical changes. To circumvent these limitations, other approaches are currently being developed and investigated with regard to different applications. These techniques are: (1) SHG, (2) THG, and (3) CARS microscopy. The main advantage of the above mentioned techniques is that they derive their imaging contrast from optical nonlinearities that do not involve fluorescence process. As a particular application of SHG-THG-CARS multimodal microscopy, we investigated collagen arrays.

Development of a tool for nanostructuring and multiphoton imaging with nanojoule femtosecond laser pulses
Paper 7201-2 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): David Bruneel, Martin Schwarz, Fraunhofer-Institut für Biomedizinische Technik (Germany); Eric Audouard, Lab. Hubert Curien (France); Ronan Le Harzic, Fraunhofer-Institut für Biomedizinische Technik (Germany)

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An integrated tool combining control and diagnostic for nanoprocessing of bio-compatible and biological materials and also allowing multiphoton large area laser scanner microscopy has been developped. This multi-function compact device is of prime interest and can be considered as a novel tool for nanoprocessing in material science, nanobiotechnology, nanomedicine. Applications in biomedicine include, for example, optoporation, cells nanodrilling, nanocutting transfection of cells, deactivation of cell organelles or investigation of cell dynamics but also potentially useful in material science for the manufacture of waveguides, gratings, micro fluidic devices, nanocontainers, data storage, nanolithography, nanomarking,…

A Shack-Hartmann wavefront sensor-based adaptive optics system for multiphoton microscopy
Paper 7209-1 of Conference 7209
Date: Wednesday, 28 January 2009
Time: 1:00 PM – 1:30 PM

Author(s): Peter T. So, Jae Won Cha, Massachusetts Institute of Technology (United States); Jérôme Ballesta, Imagine Optic (France)

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Two-photon excitation fluorescence microscopy has found many deep tissue imaging applications. The imaging depth of biological sample is partly limited by refractive index inhomogeneity in specimen. Because of this inhomogeneity, the wavefront of the excitation beam is distorted. Due to the distorted wavefront of the excitation beam, point spread function is broadened at the focal point and this leads to degraded resolution and lower signal level. For the correction of the distorted wavefront, we measure the distorted wavefront using a Shack-Hartmann wavefront sensor with the reflected light confocal detection and compensate the wavefront distortion using a deformable mirror.

Pulse-duration management of visible wavelength lasers for multiphoton photolysis applications
Paper 7193-64 of Conference 7193
Date: Wednesday, 28 January 2009
Time: 1:50 PM – 2:10 PM

Author(s): Kyle S. Gardner, Univ. of Strathclyde (United Kingdom); D. Ogden, Univ. Paris 5 (France); Erling Riis, Gail McConnell, Univ. of Strathclyde (United Kingdom)

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As multi-photon excitation applications continue to diversify, laser technology must be developed to meet the growing demands. One-such example is multi-photon photolysis, where a laser “uncages” active molecules to instigate a localised chemical interaction. Caged compounds are typically photolysed with light ~300nm, hence two-photon uncaging requires an ultrashort-pulsed source ~600-650 nm.
We report a frequency-doubled fs-pulsed Cr:Fosterite laser with pulse tailoring options, suitable for multi-photon photolysis. We will report the application of this source in multi-photon photolysis of caged glutamate, with an overview of the critical laser parameters required for efficient photo-chemical release.

Molecular design for multiphoton absorption: from the visible to telecommunications wavelengths
Paper 7213-24 of Conference 7213
Date: Wednesday, 28 January 2009
Time: 3:30 PM – 4:00 PM

Author(s): Chantal Andraud, Ecole Normale Supérieure de Lyon (France)

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Multifocal multimodal multiphoton photon counting imaging
Paper 7184-20 of Conference 7184
Date: Wednesday, 28 January 2009
Time: 5:10 PM – 5:30 PM

Author(s): Ramon Carriles, Jeffrey Field, Erich E. Hoover, Kraig E. Sheetz, Jeffrey A. Squier, Colorado School of Mines (United States)

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We have developed a novel femtosecond laser and photon detection system that, when coupled together, enables multifocal, multiphoton imaging through scattering media with single element detectors for the first time. For example, to date we have been able to image six different image areas in a single modality (e.g., two-photon absorption fluorescence imaging, second harmonic generation imaging, or third harmonic generation imaging) simultaneously, using a single photomultiplier tube. Some novel features of this imaging system, demonstrated to date include, the ability to perform multiphoton imaging at different polarizations simultaneously, image different depths simultaneously, and measure-bleaching rates for various excitation pulse shapes for fluorescently labeled systems.

Arbitrary two-dimensional multiphoton excitation patterns with temporally focused digital holograms
Paper 7184-26 of Conference 7184
Date: Thursday, 29 January 2009
Time: 9:30 AM – 9:50 AM

Author(s): Dan Oron, Weizmann Institute of Science (Israel); Valentina Emiliani, Eirini I. Papagiakoumou, Vincent de-Sars, René Descartes Univ. (France)

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A combination of temporal focusing of ultrashort pulses with digital holography is introduced. This enables us to generate arbitrary depth-resolved two-dimensional multiphoton excitation patterns completely without scanning. The depth resolution is shown to be nearly independent of the details of the illumination pattern, and is comparable to that of line-scanning multiphoton excitation. This scheme is of particular importance in applications requiring uniform excitation of large areas over short time scales, such as neuronal activation by multiphoton uncaging of neurotransmitters.

Ultrashort phase-shaped pulses for biomedical imaging
Paper 7183-32 of Conference 7183
Date: Monday, 26 January 2009
Time: 1:25 PM – 1:50 PM

Author(s): Marcos M. Dantus, Michigan State Univ. (United States) and BioPhotonic Solutions, Inc. (United States)

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The development of MIIPS (multiphoton intrapulse interference phase scan) has virtually eliminated the difficulties associated with characterization of ultrashort laser pulses and elimination of phase distortions and has allowed us to explore the use of sub-10 fs pulse for multiphoton microscopy as well as for other forms of nonlinear optical microscopy. This presentation will include some of our latest work on nonlinear optical imaging, selective nonlinear excitation, deep tissue imaging, and mass resolved ion imaging.

Atmospheric pressure femtosecond laser imaging mass spectrometry
Paper 7182-68 of Conference 7182
Date: Monday, 26 January 2009
Time: 5:30 PM

Author(s): Yves Coello, Tissa C. Gunaratne, Marcos M. Dantus, Michigan State Univ. (United States)

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We present a novel atmospheric pressure femtosecond laser imaging mass spectrometry system able to ionize and fragment molecules regardless of their size via direct multiphoton excitation, without the need for a sample matrix. Our uses amplified femtosecond laser pulses and is able to deliver transform-limited (TL) 30fs focused pulses to the sample thanks to a multiphoton intrapulse interference phase scan (MIIPS) pulse shaper that characterizes and corrects the spectral phase distortions of the pulses, ensuring efficient and reproducible ionization within the focal volume. Various samples including biological tissue have been imaged with 10 um resolution using this approach.

Doppler optical frequency domain imaging of tumor angiogenesis
Paper 7168-59 of Conference 7168
Date: Wednesday, 28 January 2009
Time: 10:30 AM – 10:45 AM

Author(s): Benjamin J. Vakoc, William W. Oh, Adrien E. Desjardins, Lisa A. Bartlett, Guillermo J. Tearney, Brett E. Bouma, Wellman Ctr. for Photomedicine (United States); Ryan M. Lanning, Timothy Padera, Dai Fukumura M.D., Rakesh K. Jain, Edwin L. Steele Lab. (United States)

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In combination with advanced animal models, optical microscopies such as fluorescence confocal and multiphoton microscopy provide a powerful set of tools for studying the complex pathophysiology of cancer. In this talk, we will describe our efforts to develop new coherence-based microscopic techniques to compliment these fluorescence microscopies for this biological application. We will describe in detail the design and construction of a Doppler optical frequency domain imaging system capable of rapid, wide-field imaging of vascular networks and tumor volumes in three-dimensions, and quantitatively compare the capabilities and limitations of this instrument relative to multiphoton techniques.

Spectroscopic characterization of extracted and in situ collagen and elastin based on multiphoton excitation microscopy and spectroscopy
Paper 7161A-103 of Conference 7161A
Date: Saturday, 24 January 2009
Time: 9:00 AM – 9:15 AM

Author(s): Jianxin Chen, Anthony Lee, Jianhua Zhao, Hequn Wang, The BC Cancer Research Ctr. (Canada); Harvey Lui, David I. McLean, Univ. of British Columbia (Canada); Haishan Zeng, The BC Cancer Research Ctr. (Canada)

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We present the spectroscopic characterization of collagen and elastin extracted from human skin dermis as well as collagen and elastin in situ within excised human skin using multiphoton excitation microscopy (MPM) and spectroscopy. We found good agreements on some aspects of the spectral properties of extracted collagen and elastin samples versus that of collagen and elastin in situ. However, there also appear to be discrepancies in other aspects of the spectral properties. For collagen second harmonic generation, there is an optimal excitation wavelength ranging from 790-nm to 850-nm. These findings will provide guidance for in vivo skin applications of MPM.

High throughput imaging based on non-descanning multifocal multiphoton microscopy using a large field of view objective
Paper 7183-105 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Jae Won Cha, Peter T. C. So, Massachusetts Institute of Technology (United States)

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Multifocal multiphoton microscope (MMM) is a promising platform for high throughput, high content tissue cytometry. However, its de-scanned emission light path geometry contributes to 30~60% signal loss. In this report, we consider the implementation of multi-anode PMT based MMM using non-descanning geometry to improve the emission signal collection efficiency. Additional crosstalk between pixels may be compensated by maximum likelihood estimation. Finally, the efficiency of the tissue image cytometer can be further improved by designing a custom large field of view, high NA objective based on improving a simple objective lens design with adaptive optics compensation.

Ultra-compact (palm-top size), low-cost, maintenance-free (>3000 h), 1.5-kW-peak-power diode-pumped femtosecond solid-state laser source for multiphoton microscopy
Paper 7183-114 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Shogo Yamazoe, Tadashi Kasamatsu, FUJIFILM Advanced Research Labs. (Japan)

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We demonstrate a novel practical femtosecond laser source, which is, to our knowledge, the smallest size and potentially low cost. The innovation is the simple linear-cavity design utilizing soliton mode-locking induced by precise group velocity dispersion control. Average output power of 680 mW and pulse width of 162 fs were obtained at around 1045 nm from a 980-nm diode-pumped Yb3+:KY(WO4)2 laser. The pulse repetition rate was 2.8 GHz, leading to a pulse peak power of 1.5 kW, which is sufficient for biomedical imaging. The laser module including the laser diode pump system has a footprint of only 8×4 cm2. Stable operation of 3000 hours was demonstrated with fluctuation of less than 10%.

Stimulated Raman scattering microscopy*
Paper 7183-43 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Wei Min, Christian W. Freudiger, Sijia Lu, Sunney Xie, Harvard Univ. (United States)

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We have developed a new multiphoton microscopy based on stimulated Raman scattering. It allows label-free chemical-selective imaging with pure vibrational spectral specificity, high sensitivity, high spatial resolution, noninvasiveness, and three-dimensional sectioning capability.

Engineered nanostructures exhibiting enhanced optical nonlinearity
Paper 7224-19 of Conference 7224
Date: Monday, 26 January 2009
Time: 1:30 PM – 2:00 PM

Author(s): Mary J. Potasek, SimPhoTek, Inc. (United States)

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Nanostructures of semiconductor quantum dots capped with surfactants and embedded in organic thin films exhibit several orders of magnitude increase in their multiphoton cross-sections of absorption relative to semiconductor quantum dots capped with surfactants in solution or in other matrix materials. Large values of optical nonlinearity have been measured for CdS and CdSe quantum dots in these engineered nanostructures. We will discuss these findings within the context of theoretically proposed hybrid excitons in organic-inorganic nanostructures. Optical nonlinear materials are valuable for applications in biomedicine, optical data storage, and telecommunications.

New developments in ultrafast lasers for non-linear imaging
Paper 7183-54 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 10:45 AM – 11:00 AM

Author(s): Marco F. Arrigoni, Coherent, Inc. (United States)

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Multiphoton microscopy has driven in recent years development of specialized ultrafast laser sources with pulse duration, tuning range and power tailored to provide optimum images. More recent trends in non-linear optics microscopy include multimodal imaging (CARS, OCT, MPE and harmonic microscopy), use of longer wavelengths and preconditioning of the laser beam parameters to better match the optical chain and obtain better, deeper images of the live sample. In this presentation I will describe recent advances in lasers sources that provide extended tuning range, pulse conditioning and other user-benefits.

Non linear manipulation and imaging of neural networks
Paper 7183-57 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 1:30 PM – 1:50 PM

Author(s): Francesco S. Pavone, Univ. degli Studi di Firenze (Italy)

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We have used multiphoton absorption as a tool for the selective lesions on the neuronal processes of cortical neurons in living mice expressing fluorescent proteins. The spatial precision of this method is demonstrated by ablating individual dendritic spines, while sparing the adjacent spines and the structural integrity of the dendrite. Furthermore, we combined the advantages of second-harmonic generation (SHG) with a random access (RA) excitation scheme to realize a new microscope (RASH microscopy) used to simultaneously record electrical activity from clusters of Purkinje cells (PCs) in acute cerebellar slices.

Broad tunability of the nonlinear properties of doped quantum dots and of core-doped quantum dot heterostructures
Paper 7189-5 of Conference 7189
Date: Saturday, 24 January 2009
Time: 10:00 AM – 10:20 AM

Author(s): Dan Oron, Assaf Avidan, Weizmann Institute of Science (Israel)

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We present an experimental study of exciton-exciton interactions in doped colloidal quantum dots, focusing on systems where only the holes are localized by the dopant, a system analogous to type-II quantum dot heterostructures. This system can be induced to exhibit very strong exciton-exciton repulsion, up to about 300meV, leading to nearly complete removal of the spectral overlap of the inhomogeneously broadened exciton and biexciton emission. The dependence of exciton-exciton repulsion on host size and on the composition of core-doped quantum dot heterostructures is discussed. Finally, we present new schemes for multiphoton microscopy utilizing the unique properties of these quantum dots.

Two-photon luminescence imaging of molecularly-targeted gold nanoparticles using a miniaturized imaging and microsurgery probe
Paper 7183-102 of Conference 7183
Date: Sunday, 25 January 2009
Time: 6:00 PM

Author(s): Christopher L. Hoy, Nicholas J. Durr, The Univ. of Texas at Austin (United States); Wibool Piyawattanametha, Hyejun Ra, Olav D. Solgaard, Stanford Univ. (United States); Adela Ben-Yakar, The Univ. of Texas at Austin (United States)

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Two-photon luminescence (TPL) from gold nanoparticles presents a bright source of contrast for multiphoton microscopy. To better exploit this technique clinically, molecularly-targeted TPL imaging can be conducted through a miniaturized two-photon microscopy probe. Furthermore, the addition of cellular-level microsurgery capabilities presents the potential for a novel “seek-and-treat” tool capable of diagnosing pathologies such as cancer at the cellular level and non-thermally ablating diseased cells while leaving neighboring cells intact. Here, we present TPL imaging of molecularly-targeted gold nanoparticles through a miniaturized optical probe capable of two-photon microscopy as well as femtosecond laser microsurgery.

Nanosecond laser-induced low-density plasmas: a new regime for nanomorphing in bulk dielectrics
Paper 7203-25 of Conference 7203
Date: Monday, 26 January 2009
Time: 3:00 PM – 3:20 PM

Author(s): Alfred Vogel, Norbert Linz, Sebastian Freidank, Joachim Noack, Univ. zu Lübeck (Germany)

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We compared ns breakdown in water at large NA using single-longitudinal mode and regular Nd:YAG laser pulses. For UV and VIS pulses with a smooth pulse shape (including those from a microchip laser) we discovered a low-density plasma regime in which nano-bubbles are created, with sizes similar to femtosecond breakdown. 3-30 times above the bubble threshold, the plasma suddenly assumes a larger size, luminesces brightly, and larger bubbles of 200 µm radius are produced. Nanoeffects could not be produced with regular pulses, and at IR wavelengths. The two-step process was successfully modeled considering thermal ionization besides multiphoton and avalanche processes.

When shorter is better
Paper 7203-31 of Conference 7203
Date: Monday, 26 January 2009
Time: 5:30 PM – 5:50 PM

Author(s): Marcos M. Dantus, Michigan State Univ. (United States) and BioPhotonic Solutions Inc. (United States)

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Ultrafast lasers have opened a whole range of applications due to their high peak intensity. Unfortunately, they are sensitive to the environment and the pulses are easily broadened. This talk will focus on how the MIIPS (multiphoton intrapulse interference phase scan) technology is being use to deliver to the target transform limited pulses with pulse durations as short as 4.6 fs. The performance of more than 16 different commercial lasers using MIIPS will be demonstrated. Micromachining results will be used to illustrate advantages from consistent delivery of ultrafast pulses through complex focusing optics.

Two-photon imaging and nanoprocessing of stem cells with sub-20 fs laser pulses
Paper 7183-45 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 8:25 AM – 8:45 AM

Author(s): Aisada A. Uchugonova, Fraunhofer-Institut für Biomedizinische Technik (Germany) and Saarland Univ. (Germany); Andreas Isemann, Femtolasers Produktions GmbH (Austria); Rainer Bückle, JenLab GmbH (Germany); Wataru Watanabe, National Institute of Advanced Industrial Science and Technology (Japan); Karsten König, Saarland Univ. (Germany) and JenLab GmbH (Germany)

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Novel ultracompact multiphoton sub-20 femtosecond near infrared 85 MHz laser scanning microscopes and conventional 250 fs laser microscopes have been used to perform high resolution multi-photon imaging of stem cell clusters as well as targeted intracellular nanoprocessing and knock-out of living single stem cells within an 3D microenvironment. Also lethal exposure of large parts of cell clusters was successfully probed while maintaining single cells of interest alive. Mean powers in the milliwatt range for 3D nanoprocessing and microwatt powers for two-photon imaging were found to be sufficient. Ultracompact low power sub-20 fs laser systems may become interesting tools for nanobiotechnology such as optical cleaning of stem cell clusters and optical transfection

Latest advances in ultra-fast laser sources for multi photon microscopy
Paper 7183-53 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 10:30 AM – 10:45 AM

Author(s): Philip G. Smith, Newport Spectra-Physics (United States)

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The advent of compact, fully automated, and widely wavelength-tunable ultrafast oscillators has triggered an explosive growth in their use in a broad array of multiphoton imaging techniques. Over the past decade laser manufacturers have constantly improved the performance characteristics of these sources to meet the requirements of the user community. We will review the latest advances at Newport / Spectra-Physics in this field and discuss new ways of optimizing key parameters for efficient deep-tissue fluorescence generation, including turn-key, automated second order dispersion compensation that allows for optimization of the pulse width at the sample over a wide wavelength range, without compromising beam pointing and other critical beam parameters.

1230nm-based least-invasive third and second harmonic generation imaging of ocular tissues
Paper 7183-61 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 2:40 PM – 2:55 PM

Author(s): Szu-Yu Chen, Chi-Kuang Sun, National Taiwan Univ. (Taiwan); Han-Chieh Yu, I-Jong Wang, National Taiwan Univ. Hospital (Taiwan)

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Cornea functions as an outermost lens and plays an important role in vision. For cornea diagnosis and treatment such as refractive surgery, a microscopic imaging system with cellular resolution and eye safety is strongly desired. Recently, confocal and multiphoton microscopy have been applied to clinical applications with visible to near-infrared light sources. To increase the eye safety, a light source with longer wavelength would be needed. In this presentation, an infrared-based based harmonic generation microscopy study of mouse eyes is demonstrated, since most of auto-fluorescence was suppressed under IR excitation, with ~700m penetrability achieved.

Nonlinear microscopic properties of starch granules
Paper 7183-62 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 2:55 PM – 3:10 PM

Author(s): Richard Cisek, Nicole Prent, Univ. of Toronto at Mississauga (Canada); Arkady Major, Univ. of Manitoba (Canada); Virginijus Barzda, Univ. of Toronto at Mississauga (Canada)

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Systematic investigation of nonlinear optical properties of individual starch granules has been performed with a multicontrast multiphoton excitation fluorescence, second harmonic generation (SHG) and third harmonic generation (THG) microscope. The SHG image of a starch granule visualizes the orientation of the linear polarization of the laser, or reveals the circular polarization. The SHG cancels in the center of starch granule due to the centrosymmetric organization. The forward and backward radiation of SHG reveals different intensity distribution within starch. Large variation in morphology of the granules reveals different structural organization of starch. The harmonic microscopy is beneficial for studying starch in vivo, as well as for food quality control and optimization of biofuel production.

Integration of photonic crystal fibres and MEMS for nonlinear optical endoscopy
Paper 7219-14 of Conference 7219
Date: Thursday, 29 January 2009
Time: 11:00 AM – 11:30 AM

Author(s): Min Gu, Swinburne Univ. of Technology (Australia)

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Excitonic effects on optically induced ultrafast currents in GaAs quantum wells
Paper 7214-3 of Conference 7214
Date: Sunday, 25 January 2009
Time: 8:56 AM – 9:24 AM

Author(s): Mark Bieler, Shekhar Priyadarshi, Klaus Pierz, Uwe Siegner, Physikalisch-Technische Bundesanstalt (Germany); Philip Dawson, The Univ. of Manchester (United Kingdom)

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We have studied the influence of excitonic effects on two different types of ultrafast current transients that are induced in unbiased semiconductor structures by all-optical excitation. While injection currents result from quantum interference between different absorption pathways, shift currents are generated by the spatial shift of the center of the electron charge during optical excitation. Our experimental results show that Coulomb effects substantially affect the properties of shift and injection currents.

Modeling the nanoplasmonics-enhanced ultrafast laser interaction on biological tissue
Paper 7203-2 of Conference 7203
Date: Sunday, 25 January 2009
Time: 9:00 AM – 9:20 AM

Author(s): Etienne Boulais, Guillaume Poulin, Michel Meunier, Ecole Polytechnique de Montréal (Canada)

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Student paper for competition
Interest in hyperthermia therapy for tumor destruction is stimulated by recent advances in plasmonic nanostructures synthesis. Structures such nanorods exhibit plasmon resonance in the near infrared portion of the spectrum, enabling treatment in deep tissues. However, there is a lack of a quantitative description of the temperature profile induced in the tumor and its surrounding by the process. In the present study, 3D electromagnetic field distribution and tissue transient temperature distribution is calculated for embedded nanoplasmonic structures after an interaction with an ultrafast laser pulse. Temperature profile induced in the tissue is then calculated for different laser pulse fluences.

Imaging carrier and phonon transport in Si using ultrafast optical pulses
Paper 7214-5 of Conference 7214
Date: Sunday, 25 January 2009
Time: 10:15 AM – 10:43 AM

Author(s): David H. Hurley, Idaho National Lab. (United States); Oliver B. Wright, Osamu Matsuda, Hokkaido Univ. (Japan); Brian McCandless, Univ. of Delaware (United States)

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We microscopically image thermal diffusion and surface acoustic phonon propagation within a single crystallite of a polycrystalline Si sample. The experimental approach employs ultrafast optical pulses to generate an electron-hole plasma and a second probe pulse is used to image the evolution of the plasma. By decomposing the signal into a component that vary with delay time and a steady state component that varies with pump modulation frequency, the respective influence of carrier recombination and thermal diffusion are identified. Additionally, the coherent surface acoustic phonon component to the signal is imaged using a Sagnac interferometer to monitor optical phase.

Ultrafast far-infrared optics of carbon nanotubes
Paper 7214-9 of Conference 7214
Date: Sunday, 25 January 2009
Time: 1:20 PM – 1:48 PM

Author(s): Christian Frischkorn, Freie Univ. Berlin (Germany)

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Time-resolved THz spectroscopy is used to investigate the carrier dynamics in carbon nanotubes, which allows to monitor the energy relaxation of the optically excited electrons. The energy of the pump pulse initially deposited into the electronic system is rapidly dissipated to only few strongly coupled optical phonons which heat up within few hundreds of femtoseconds. Subsequent cooling of these phonon modes is observed on a picosecond time-scale which is substantially faster in nanotubes than in graphite pointing to stronger lattice anharmonicities. Temperature dependent measurements show the hot phonon decay proceeding via generation of cold phonons like high-frequency optical phonon and radial breathing modes.

Introduction to Ultrafast Technology
Date: Sunday, 25 January 2009
Time: 1:30 PM – 5:30 PM

Author(s): Rick P. Trebino, Georgia Institute of Technology (United States)

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Ultrafast adaptive nanooptics
Paper 7214-10 of Conference 7214
Date: Sunday, 25 January 2009
Time: 1:48 PM – 2:16 PM

Author(s): Walter Pfeiffer, Univ. Bielefeld (Germany); Tobias Brixner, Dmitri V. Voronine, Univ. Würzburg (Germany); F. Javier Garcia de Abajo, Consejo Superior de Investigaciones Científicas (Spain); Martin Aeschlimann, Univ. Kaiserslautern (Germany); Michael K. Bauer, Christian-Albrechts-Univ. zu Kiel (Germany)

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Control of spatial and temporal properties of near-fields provides fascinating possibilities for nanoscale spectroscopy and manipulation of quantum systems. Recent progress to flexibly control such near-fields using optimally polarization-shaped femtosecond laser pulses is presented.

Ultrafast optical and terahertz spectroscopy of carrier relaxation and recombination dynamics in graphene
Paper 7214-11 of Conference 7214
Date: Sunday, 25 January 2009
Time: 2:16 PM – 2:44 PM

Author(s): Farhan Rana, Cornell Univ. (United States)

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Using optical-pump/optical-probe and optical-pump/terahertz-probe spectroscopies we study the ultrafast intraband relaxation and interband recombination dynamics of photoexcited electrons and holes in graphene. We find three distinct processes with their respective time scales. On short ~15-150 fs time scales, the photoexcited carriers thermalize and acquire a hot Fermi-Dirac distribution. On ~0.15-1.5 ps time scales, the hot carriers cool due to phonon scattering. On ~1.5-15 ps time scales, the photogenerated electrons and holes recombine. The recombination times are found to be carrier density dependent.

Ultrafast semiconductor quantum optics
Paper 7214-13 of Conference 7214
Date: Sunday, 25 January 2009
Time: 3:12 PM – 3:40 PM

Author(s): Rudolf Bratschitsch, Univ. Konstanz (Germany)

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Semiconductor quantum dots are promising systems for robust and scalable quantum information processing. Ultrafast sequences of coherent quantum operations may be envisioned with femtosecond light pulses, if the involved quantum states are separated by at least tens of meV. We present two-color femtosecond pump-probe spectroscopy on a single self-assembled CdSe/ZnSe quantum dot. The transient quantum dynamics is probed with resonant excitation and detection. Ultrafast Coulomb renormalization and single exciton gain are observed with these first resonant pump-probe measurements on a single-electron system. We will also discuss strategies to increase the light-quantum dot coupling via optical nanoantennas and microresonators.

Photoinduced ultrafast structural dynamics of nanomaterials
Paper 7214-14 of Conference 7214
Date: Sunday, 25 January 2009
Time: 4:00 PM – 4:28 PM

Author(s): Jau Tang, Pying Yu, Po-Tze Tai, Sheng-Hsien Lin, Academia Sinica (Taiwan)

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We will report our study of photoinduced structural dynamics of nanomaterials of various shapes and sizes by a femtosecond laser heating pulse as detected by time-resolved electron diffraction or transient optical absorption. This work improves the understanding of nanoscale heat transfer and the ultrafast structural dynamics in nanomaterials such as thin films, spheres, prisms, disks, rods, pyramids and cubes. This work allows us to elucidate the roles of dynamic expansion/contraction and the more well-known static linear expansion.

Control of ultrafast pulse propagation in semiconductor components
Paper 7214-19 of Conference 7214
Date: Monday, 26 January 2009
Time: 8:28 AM – 8:56 AM

Author(s): Mike van der Poel, Per L. Hansen, Yaohui Chen, Kresten Yvind, Jesper Mørk, Danmarks Tekniske Univ. (Denmark)

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Time shifting of optical pulses with duration in the range from 100 fs to a few ps represents one extreme of slow light, where THz bandwidth for the slow down or speed up is necessary. The physics of the time shifting of such very short pulses involves the gain saturation of the optical medium and is different from the slow-light mechanisms responsible for time shifting of pulses of more narrow bandwidth. Experimental and theoretical results with semiconductor components are presented, emphasizing the physics as well as the limitations imposed by the dynamical processes.

Four-dimensional visualization of ultrafast nuclear motion by electron diffraction
Paper 7214-21 of Conference 7214
Date: Monday, 26 January 2009
Time: 9:24 AM – 9:52 AM

Author(s): Peter N. Baum, Ludwig-Maximilians-Univ. München (Germany) and California Institute of Technology (United States)

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Dynamical changes in condensed matter and molecules involve motion of atoms and electrons from initial to final conformations. To observe such rearrangements in space and time, picometer resolution and femtosecond timing are required. Ultrashort electron pulses, because of their short De Broglie wavelength, allow to directly visualize atomic-scale motions in all four dimensions. Recent results on solid-to-solid phase transformations in vanadium dioxide and ultrafast laser ablation of graphite will be discussed, and concepts for the generation of free attosecond electron pulses will be presented, in order to eventually reach the time scale of electron motions with ultrafast diffraction.

Compact ultrafast lasers based on quantum-dot structures
Paper 7222-16 of Conference 7222
Date: Monday, 26 January 2009
Time: 9:30 AM – 10:00 AM

Author(s): Edik U. Rafailov, M. A. Cataluna, K. G. Wilcox, S. A. Zolotovskaya, Univ. of Dundee (United Kingdom)

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Novel materials, notably quantum-dot (QD) semiconductor structures offer the unique possibility of combining exploitable spectral broadening of both gain and absorption with ultrafast carrier dynamic properties. Thanks to these characteristics QD based devices have enhanced the properties of ultrashort pulse lasers and opened up new possibilities in ultrafast science and technology. In this paper we will review recent results, which demonstrate that quantum-dot structures can be designed to provide compact and efficient ultrashort pulse laser sources with high and low repetition rates.

CARS microscopy using linearly-chirped ultrafast laser pulses
Paper 7183-29 of Conference 7183
Date: Monday, 26 January 2009
Time: 11:10 AM – 11:25 AM

Author(s): Israel Rocha-Mendoza, Wolfgang W. Langbein, Paola Borri, Cardiff Univ. (United Kingdom)

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We present a home-built CARS microscope which exploits linearly-chirped ultrafast laser pulses. Using glass blocks of calibrated group-velocity dispersion, the CARS Stokes and Pump pulses are equally chirped to pulse durations ranging from 400fs to 2ps. For short durations, a Pump pulse arriving on the tailing edge of the Stokes optimizes the CARS signal and reduces the non-resonant CARS. For long durations, corresponding to a spectral width of the instantaneous frequency difference lower than the Raman linewidth, the timing is no longer critical, and the highest signal to non-resonant background ratio is achieved.

Latest developments of ultrafast fiber laser and its material applications
Paper 7214-26 of Conference 7214
Date: Monday, 26 January 2009
Time: 1:20 PM – 1:48 PM

Author(s): Gyu Cheon Cho, Bing Liu, Lawrence Shah, Zhenlin Liu, Yong Che, Jingzhou Xu, IMRA America, Inc. (United States)

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Increasing research activities have undertaken in generation of ultrashort pulses based on fiber laser in very recent years. Generation of high energy pulse at a high average power out of a fiber laser has been one of the main challenges, which can significantly broaden perspectives of both spectroscopic and material applications. In fact, fiber lasers have been considered to be an advantageous alternative of many lasers based on free-space optics. Realization of a compact and environmentally stable ultrafast laser easy to operate has become thereby a very critical factor. In this presentation we will present the recent development of ultrafast fiber laser and its application in material research.

Ultrafast imaging of plasmas produced in conditions of femtosecond waveguide writing in dielectrics
Paper 7203-23 of Conference 7203
Date: Monday, 26 January 2009
Time: 2:20 PM – 2:40 PM

Author(s): Wojciech Gawelda, Daniel Puerto Garcia, Jan Siegel, Alejandro Ruiz de la Cruz, Andrés Ferrer Moreu, Marcial Galván Sosa, Francisco Javier Solís Céspedes, Consejo Superior de Investigaciones Cientificas (Spain)

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Femtosecond laser-induced plasmas in bulk dielectrics are imaged under waveguide writing conditions and their temporal evolution is observed using ultrafast pump-probe microscopy. The results, obtained using an elliptically shaped beam, allow identifying multiple beam filamentation and pre-focal energy depletion as important energy loss channels, which deteriorate the spatial distribution of the laser-deposited energy. Time-resolved images of the interaction volume show how these undesirable effects can be minimized via pulse duration, energy and polarization at a given processing depth. As a consequence, energy deposition in the focal region is greatly enhanced leading to the production of waveguides with optimized performance.

Ultrafast dual-laser system for picosecond acoustics
Paper 7203-28 of Conference 7203
Date: Monday, 26 January 2009
Time: 4:30 PM – 4:50 PM

Author(s): Eric P. Mottay, Pierre Rigail, Amplitude Systemes (France); Claire Bastianelli, Sebastien Ermeneux, ALPhANOV (France); Clement Rossignol, Jean-Michel Rampnoux, Stefan Dilhaire, Univ. Bordeaux I (France)

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We present a new compact ultrafast laser system dedicated to thermal and acoustic measurements in the picosecond time domain. The system uses two ultrafast diode-pumped Ytterbium oscillator, whose repetition rates are slightly shifted and synchronised. The laser is used in an asynchronous optical sampling configuration, does not use any delay line, and allow for extremely fast measurements, with a picosecond temporal resolution and long acquisition time, up to 20 ns. We report on the application of this system to thermal and acoustic measurements in micro-electronics applications.

Three dimensional (3D) lithographic microfabrication based on ultrafast optical pulse manipulation
Paper 7183-46 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 8:45 AM – 9:05 AM

Author(s): Daekeun Kim, Peter T. C. So, Massachusetts Institute of Technology (United States)

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Two-photon excitation microfabrication allows 3D fabrication at micrometer scale, but fabrication speed is limited by the point-by-point writing process. In this paper, we introduce two-photon excitation 3D lithographic microfabrication based on wide-field illumination induced by temporal focusing. Modulating ultrafast optical pulse generates temporal focusing and it enables depth-resolved lithographic processing using wide-field illumination. We derive a mathematical model for optical resolution in order to identify the design parameters that affect optical resolution. This model is further confirmed by empirical measurements.

New developments in ultrafast lasers for non-linear imaging
Paper 7183-54 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 10:45 AM – 11:00 AM

Author(s): Marco F. Arrigoni, Coherent, Inc. (United States)

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Multiphoton microscopy has driven in recent years development of specialized ultrafast laser sources with pulse duration, tuning range and power tailored to provide optimum images. More recent trends in non-linear optics microscopy include multimodal imaging (CARS, OCT, MPE and harmonic microscopy), use of longer wavelengths and preconditioning of the laser beam parameters to better match the optical chain and obtain better, deeper images of the live sample. In this presentation I will describe recent advances in lasers sources that provide extended tuning range, pulse conditioning and other user-benefits.

Ultrafast carrier dynamics and laser action in ZnO nanowires
Paper 7214-38 of Conference 7214
Date: Tuesday, 27 January 2009
Time: 1:00 PM – 1:28 PM

Author(s): Marijn A. M. Versteegh, Ruben E. C. van der Wel, Benjamin J. M. Brenny, Bas Zegers, Wouter Ensing, Jaap I. Dijkhuis, Univ. Utrecht (Netherlands)

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To examine the mechanism responsible for laser action at room temperature, we have performed ultrafast time- and wavelength-resolved pump-probe gain measurements on a ‘forest’ of 100-500 nm thick and 20 µm long ZnO nanowires. When we pump at the highest fluences and probe at 385 nm or 390 nm, we observe strong amplification, accompanied by a decay of the gain on the subpicosecond time scale, which we attribute to stimulated emission by a degenerate electron-hole plasma. The fast decay is followed by a slow, non-uniexponential decay, which points to stimulated emission by a non-degenerate electron-hole plasma.

Ultrafast all-optical photonic integrate circuits: nonlinear optics on a chip
Paper 7212-23 of Conference 7212
Date: Tuesday, 27 January 2009
Time: 1:10 PM – 1:40 PM

Author(s): Benjamin J. Eggleton, The Univ. of Sydney (Australia)

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This paper reviews recent progress in developing highly nonlinear ultrafast all-optical processing photonic integrated circuits. Highly nonlinear chalcogenide glass provides ultrafast optical nonlinearity with low two-photon absorption and negligible free-carriers. Highlights include: low-threshold supercontinuum generation, optical switching at 640Gb/s and efficicent parametric amplification.

Novel ultrafast semiconductor lasers based on surface-emitting lasers
Paper 7193-44 of Conference 7193
Date: Tuesday, 27 January 2009
Time: 1:50 PM – 2:20 PM

Author(s): Ursula Keller, ETH Zürich (Switzerland)

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Diode-pumped solid-state lasers supported pulse repetition rates as high as 160 GHz and motivated a new approach replacing the ion-doped solid-state laser with a vertical external cavity surface emitting laser (VECSEL), which has generated picosecond pulses with more than 2 W of average output power. SESAM modelocked VECSELs support further integration of gain and saturable absorber within one wafer and ultimately electrical pumping. Such modelocked integrated external-cavity surface emitting lasers (MIXSELs) offer an ultrafast laser technology that is scalable between 10 and 100 GHz and enable new applications where todays ultrafast lasers are considered too bulky and expensive.

Ultrafast electronic transport and relaxation dynamics in low-dimensional semiconductor nanostructures
Paper 7214-41 of Conference 7214
Date: Tuesday, 27 January 2009
Time: 2:24 PM – 2:52 PM

Author(s): Hyunyong Choi, Lawrence Berkeley National Lab. (United States) and Univ. of California, Berkeley (United States); Theodore B. Norris, Univ. of Michigan (United States); Jerome Faist, ETH Zürich (Switzerland); Federico Capasso, Harvard Univ. (United States)

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Ultrafast time-resolved pump-probe measurements are used to study low energy excitations and dynamics of electronic transport in various semiconductor nanostructures. In quantum cascade lasers, we observe ultrafast gain recovery dynamics due to electronic transport in the structures.

5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7201-38 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

5D multiphoton microscopy: in-situ diagnostics for ultrafast laser 3D nanofabrication
Paper 7203-38 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Jianzhao Li, Shane M. Eaton, Peter R. Herman, Univ. of Toronto (Canada)

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An ultrafast-laser optical system has been developed that combines nano-scale machining with 5-dimensional (3 spatial dimensions + time + wavelength spectrum) optical microscopy to enable on-the-fly diagnostic feedback for target alignment and optimizing femtosecond laser interactions. Laser-interaction volumes were temporally and spectrally characterized in situ during laser-formation of buried optical waveguides in bulk glasses. Broadband photo emission is shown to temporally follow the dynamics of thermal diffusion with a definitive onset of prolonged heat accumulation effect above ~300 kHz repetition rate (at ~200 nJ pulse energy) in borosilicate glass. The spectral emission is attributed to thermally-activated photoluminescence that correlates with reduced waveguide loss. In this way, a new means for intelligent laser processing is identified to actively control optical waveguide quality during processing.

Compact, rigid, and high-power ultrafast laser system applying a glass-block cavity
Paper 7193-104 of Conference 7193
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Shin-Ichiro Aoshima, Shingo Oishi, Toshiharu Moriguchi, Yoichi Kawada, Masatoshi Fujimoto, Katsumi Shibayama, Masaomi Takasaka, Kenshi Fukumitsu, Shigeru Sakamoto, Koei Yamamoto, Hamamatsu Photonics K.K. (Japan)

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We developed a compact Yb:YAG ceramic regenerative amplification system using a rectangle glass block in its cavity. A pulse to be amplified is propagated in a long distance in the glass block by being reflected repetitively at end faces of glass under the condition of total internal reflection. Furthermore, we developed transmission gratings that have a diffraction efficiency of more than 95%. Finally, we have succeeded in reducing the floor area of an amplifier down to less than 2,000 cm^2. We obtained 1.2-ps compressed pulses of 4-W average power, i.e. 0.20-mJ energy at a repetition rate of 20 kHz.


Ultrafast-pulse generation and shaping in dispersion oscillating fibers
Paper 7195-88 of Conference 7195
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Alexej A. Sysoliatin, A.M. Prokhorov General Physics Institute (Russian Federation); Andrey I. Konyukhov, Leonid A. Melnikov, Saratov State Univ. (Russian Federation); Vladimir A. Stasyuk, PriTel Inc. (United States)

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In this work we propose a novel method to generate and control the ps and subps optical pulses by its amplitude and width in dispersion oscillating
fiber (DOF). In such a fiber with periodically modulated dispersion, when the oscillation period approaches the soliton period, the resonance effects take place. Simulation and experimental results indicate that the DOF fibers could have the different applications in optical signal processing (like LC-contour in microwave). In addition, a possibility to change the waveguide
parameters along the fiber length results to increasing of the SBS threshold by 7dB over the conventional nonlinear fibers.

Ultrafast exciton dynamics of highly excited bulk ZnO
Paper 7214-47 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 8:28 AM – 8:56 AM

Author(s): Tina Shih, Harvard Univ. (United States); Jan-Peter Richters, Tobias Voss, Univ. Bremen (Germany); Eric D. Mazur, Harvard Univ. (United States)

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Advances in ZnO-based device technologies rely on a fundamental understanding of carrier dynamics and excitonic effects at high excitation densities. With intense, ultrashort, 266-nm laser pulses, we are able to monitor exciton dynamics in m-plane and c-plane ZnO in a micro-cryostat pump-probe reflectometry setup. Depending on the excitation fluence, the reflectivity data show a damping of the ZnO exciton resonances after fs-laser excitation, which are accurately described by theoretical reflectivity calculations.

Transform limited high-energy and high-average-power ultrafast fiber amplifier
Paper 7195-37 of Conference 7195
Date: Wednesday, 28 January 2009
Time: 8:30 AM – 8:50 AM

Author(s): Yoann Zaouter, Eric P. Mottay, Amplitude Systemes (France); Johan Boullet, Eric Cormier, Univ. Bordeaux I (France)

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We report on a high energy (> 100 microJoules), high average power (> 30W), short duration (270 fs) ultrafast fiber amplifier, with an excellent temporal and spectral quality (1.1 times the Fourier limit). Although high energy and very high average power has been already demonstrated in both nanosecond and CW operation, power scaling of ultrafast single-mode fiber amplifiers has been restricted by the non-linearities induced phase distorsions. The laser uses the chirped pulse amplification technique, where nonlinear phase shifts are exploited in conjunction with a mismatched stretcher and compressor.

Analyzing ultrafast carrier and spin dynamics in III-V semiconductors with optical orientation methods
Paper 7214-48 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 8:56 AM – 9:24 AM

Author(s): Markus Betz, Christine Hautmann, Florian Jaworeck, Markus Wesseli, Technische Univ. München (Germany)

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Ultrafast optical orientation methods are widely used to study ultrafast carrier spin dynamics. Here, electron spin relaxation times in n-doped and nominally undoped bulk GaSb are measured with time-resolved circular dichroism and Faraday rotation induced by 1.55 µm, 150 fs pulses. We find 4-35 ps time constants with a strong temperature dependence. Many aspects of the results are realted to the large spin-orbit coupling in GaSb, consistent with D'yakonov-Perel type spin relaxation. In similar experiments in GaAs at 800 nm, we additionally use spectral resolution within the ultrabroadband probe pulse. We show that, in addition to electron spin dynamics, also ultrafast energy relaxation of nonequilibrium carriers can be analyzed with time-resolved Faraday rotation.

Ultrafast response of negative-index metamaterials in the near infrared
Paper 7205-30 of Conference 7205
Date: Wednesday, 28 January 2009
Time: 11:20 AM – 11:40 AM

Author(s): David J. Cho, Feng Wang, Xiang Zhang, Yuen-Ron Shen, Univ. of California, Berkeley (United States); Wei Wu, Ekaterina Ponizovskaya, Hewlett-Packard Labs. (United States); Pratik Chaturvedi, Univ. of Illinois at Urbana-Champaign (United States); Alexander M. Bratkovksy, Shih-Yuan Wang, Hewlett-Packard Labs. (United States)

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Nanoimprint lithography is used to fabricate a metamaterial with the “fishnet” structure composed of Ag/α-Si/Ag layers that exhibits negative refractive index in the near-infrared. We have carried out a femtosecond pump-probe experiment to measure the transient photo-induced response of this structure. With a pump fluence of 330uJ/cm2 at 800 nm, the transmission at the magnetic resonance is increased by ~15.4%. The induced change originated from carrier excitation in the α-Si layer has a fast decay constant of 1.1ps.

Ultrafast dynamics of InN thin films
Paper 7214-53 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 11:39 AM – 12:07 PM

Author(s): Der-Jun Jang, Guan-Tin Lin, Ching-Lien Hsiao, Li-Wei Tu, National Sun Yat-sen Univ. (Taiwan); Meng-En Lee, National Kaoshiung Normal Univ. (Taiwan)

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The ultrafast dynamics of InN thin films grown on Si(111) subtracts has been studied by a time-resolved photoluminescence upconversion apparatus. The obtained carrier cooling curves can be explained by carriers releasing excessive energy through the carrier–LO-phonon interaction. The extracted effective phonon emission times increase with the photoexcited carrier concentration due to the hot phonon effect and come close to the theoretical prediction of 23 fs at small photoexcited carrier concentration. The study of the time-resolved photoluminescence at the band gap energy concludes that the Auger rates are small at low carrier concentrations but increase quadratically with the carrier concentration.

High-energy ultrafast thin-disk oscillators
Paper 7193-62 of Conference 7193
Date: Wednesday, 28 January 2009
Time: 1:00 PM – 1:30 PM

Author(s): Joerg Neuhaus, Univ. of Konstanz (Germany) and TRUMPF Laser GmbH & Co KG (Germany); Dominik Bauer, TRUMPF Laser GmbH & Co KG (Germany) and Univ. of Konstanz (Germany); Dirk H. Sutter, Jochen Kleinbauer, Sascha Weiler, Alexander Killi, TRUMPF Laser GmbH & Co KG (Germany); Thomas Dekorsy, Univ. of Konstanz (Germany)

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We present recent results on ultrafast pulse generation with record pulse energies of tens of microjoules directly from a laser oscillator. At repetition rates of a few megahertz, average powers of many tens of watts are obtained from a mode-locked thin-disk resonator without any need for further amplifier stages. Technological advantages are discussed with respect to alternative concepts for industrial ultrafast lasers.

Ultrafast electron-phonon and phonon-phonon scattering in highly doped semiconductors
Paper 7214-54 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 1:20 PM – 1:48 PM

Author(s): Jacob B. Khurgin, The Johns Hopkins Univ. (United States)

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We study the interaction between electron, and optical and acoustic phonons in the channel of field effect transistor. We show that the intra-branch scattering of LO phonons due to disorder and interaction with hot electrons plays pivotal role in the LO phonon decay and is thus ultimately responsible for cooling of electrons and the performance of the transistor at high power. Our theoretical results are confirmed by the experiemnal studies done in collaboration.

Ultrafast Fiber Lasers
Date: Wednesday, 28 January 2009
Time: 1:30 PM – 5:30 PM

Author(s): Martin E. Fermann, IMRA America, Inc. (United States)

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News applications in authentication and traceability using ultrafast laser marking
Paper 7201-31 of Conference 7201
Date: Wednesday, 28 January 2009
Time: 2:00 PM – 2:30 PM

Author(s): Zbigniew Sagan, Benjamin Dusser, ATT Advanced Track & Trace (France)

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Ultrafast carrier dynamics on Si surfaces studied by time-resolved two-photon photoemission spectroscopy
Paper 7214-59 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 3:40 PM – 4:08 PM

Author(s): Katsumi Tanimura, Osaka Univ. (Japan)

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Carrier dynamics on semiconductor surfaces is of great scientific and technological interest. In combination with carrier diffusion and drift transport, ultrafast primary processes of carrier-carrier (e-e) scattering and electron-phonon (e-p) scattering in bulk electronic states, govern the dynamics near surfaces. In spite of the accumulating knowledge, no direct picture of the carrier relaxation in bulk states nor of dynamical coupling of bulk electrons to intrinsic Si surface states have emerged.
We study ultrafast carrier relaxation in Si by means of time-resolved two-photon photoemission spectroscopy with tunable fs lasers as the pump light...

Ultrafast optical spin rotation in semiconductors
Paper 7225-18 of Conference 7225
Date: Wednesday, 28 January 2009
Time: 4:50 PM – 5:15 PM

Author(s): Hailin Wang, Univ. of Oregon (United States)

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Recent experimental progresses on realizing ultrafast spin rotation of localized electron spins as well as electron spins in two-dimensional electron gas will be presented.

Ultrafast nanowire superconducting single-photon detector with photon number resolving capability
Paper 7236-12 of Conference 7236
Date: Thursday, 29 January 2009
Time: 10:20 AM – 11:00 AM

Author(s): Gregory N. Goltsman, Moscow State Pedagogical Univ. (Russian Federation)

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An overview of the state-of-the-art of the nanowire superconducting single-photon detector (SSPD) is presented. At 2K temperature the SSPD demonstrate superb characteristics: up to 30% quantum efficiency at 1300nm wavelength, dark counts rate below 2*10^-4 s^-1, 200 ps pulse duration with 16 ps timing jitter. SSPD was successfully used in single-photon sources characterization and quantum cryptography.
A photon number resolving SSPD was developed. The advantage of our approach is scalability to resolve tens of photons. It bridges the gap between single-photon detectors and traditional detectors with the response linear to the power.

Ultrafast parametric oscillators for spectroscopy
Paper 7193-84 of Conference 7193
Date: Thursday, 29 January 2009
Time: 1:20 PM – 1:50 PM

Author(s): Derryck T. Reid, Lukasz W. Kornaszewski, T. P. Mueller, Nicolas Gayraud, William N. MacPherson, Duncan P. Hand, James M. Stone, Jonathan C. Knight, Heriot-Watt Univ. (United Kingdom)

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The high spatial coherence, wide tunability and broad intrinsic bandwidth of femtosecond optical parametric oscillators makes them uniquely attractive sources for spectroscopy in the visible and infrared. Using systems based on MgO:PPLN, and pumped by a self-modelocked Ti:sapphire laser, we have shown free-space and photonic-crystal-fibre-based spectroscopy of methane to concentrations as low as 50 ppm. New diode-pumped solid-state ultrafast lasers are now able to exceed the performance of Ti:sapphire lasers and we will describe performance obtained using a Yb:fibre-pumped OPO that so far has produced 20 nJ pulses directly from the oscillator, with the potential for energy scaling to ~1 µJ levels.

Multimodal ultrafast spectroscopy system based on 35-fs Ti:Sapphire CPA laser
Paper 7193-85 of Conference 7193
Date: Thursday, 29 January 2009
Time: 1:50 PM – 2:10 PM

Author(s): Ruben Zadoyan, Newport Corp. (United States)

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I will describe a flexible and easily configurable ultrafast spectroscopy setup based on 1kHz 3mJ 35fs amplified Ti:Sapphire laser. The setup consisting of several independently operated modules is well suited for Transient Absorption, CARS, FWM, 2D IR and other ultrafast spectroscopies. As an example, experimental data on several iquids, colloidal samples and conjugated polymers will be presented.

Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell
Paper 7214-6 of Conference 7214
Date: Sunday, 25 January 2009
Time: 10:43 AM – 11:11 AM

Author(s): Michael R. Armstrong, Jonathan C. Crowhurst, Evan J. Reed, Joseph M. Zaug, Lawrence Livermore National Lab. (United States)

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We use sub-picosecond laser pulses to launch ultra-high strain rate (~10^9/s) nonlinear acoustic waves into a methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which may result in shock wave behavior. We compare our results with low strain, low strain-rate acoustic data. This technique provides controlled access to regions of thermodynamic phase space that are otherwise difficult to obtain.

Photo-induced insulator-metal phase transition observed by the terahertz pump-probe spectroscopy
Paper 7214-25 of Conference 7214
Date: Monday, 26 January 2009
Time: 11:39 AM – 12:07 PM

Author(s): Makoto Nakajima, Naoko Takubo, Zenji Hiroi, Yutaka Ueda, Tohru Suemoto, The Univ. of Tokyo (Japan)

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The ultrafast terahertz response to the photoexcitation in vanadium dioxide was investigated using the optical-pump terahertz-probe technique at room temperature. The optical excitation induced an ultrafast decrease of the transmittance of the terahertz pulses within ~ 1 ps, and then the transmittance decreases gradually up to 100 ps. This two step behaviour is very similar to the previous reports of the time resolved X-ray and electron diffractions. This fact indicates that the increase of the electronic conductivity and the change of the lattice structure proceed in parallel. This observed signal is ascribed to the generation of the metallic state.

Ultrafast Yb:YAG thin-disk oscillator with pulse energies exceeding 25 μJ suitable for efficient ablation with negligible heat affects
Paper 7203-26 of Conference 7203
Date: Monday, 26 January 2009
Time: 3:50 PM – 4:10 PM

Author(s): Joerg Neuhaus, Univ. of Konstanz (Germany); Dominik Bauer, TRUMPF Laser GmbH & Co. KG (Germany) and Univ. of Konstanz (Germany); Christoph Scharfenberg, Jochen Kleinbauer, Alexander Killi, Sascha Weiler, Dirk H. Sutter, TRUMPF Laser GmbH & Co. KG (Germany); Thomas Dekorsy, Univ. of Konstanz (Germany)

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We report on the highest pulse energies ever obtained directly from an ultrafast oscillator without additional amplifier stages: Twenty-five microjoules are generated using an active multi-pass, TEM00 thin-disk resonator operating in air. Passive soliton mode-locking in the sub-picosecond regime is started and stabilized by a semiconductor saturable absorber mirror. An external modulator allows for user-selectable pulse energies and repetition rates. The average power exceeds 70W and could be scaled further, both in terms of pulse energy as well as repetition rate. A simple laboratory setup already allows for surface structuring with negligible heat affects and high productivity.

When shorter is better
Paper 7203-31 of Conference 7203
Date: Monday, 26 January 2009
Time: 5:30 PM – 5:50 PM

Author(s): Marcos M. Dantus, Michigan State Univ. (United States) and BioPhotonic Solutions Inc. (United States)

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Ultrafast lasers have opened a whole range of applications due to their high peak intensity. Unfortunately, they are sensitive to the environment and the pulses are easily broadened. This talk will focus on how the MIIPS (multiphoton intrapulse interference phase scan) technology is being use to deliver to the target transform limited pulses with pulse durations as short as 4.6 fs. The performance of more than 16 different commercial lasers using MIIPS will be demonstrated. Micromachining results will be used to illustrate advantages from consistent delivery of ultrafast pulses through complex focusing optics.

Three-dimensional photonic devices fabricated by ultrafast lasers for optical sensing in lab-on-a-chip
Paper 7201-35 of Conference 7201
Date: Tuesday, 27 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Rebeca Martinez Vazquez, Roberto Osellame, Politecnico di Milano (Italy); Chaitanya Dongre, Hugo J. Hoekstra, Markus Pollnau, Univ. Twente (Netherlands); Hans H. van den Vlekkert, Lionix BV (Netherlands); Rob van Weeghel, Zebra Bioscience B.V. (Netherlands); Paul Watts, The Univ. of Hull (United Kingdom); Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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A lab-on-a-chip (LOC) is a device that incorporates in a single substrate the functionalities of a biological laboratory with micrometer dimensions. The next technological challenge of LOCs is direct on-chip integration of photonic functionalities. Ultrafast laser processing of the bulk of a dielectric material is a very flexible and simple method to produce photonic devices inside microfluidic chips for capillary electrophoresis (CE) or chemical microreactors. In this work we report on the use of femtosecond laser pulses to fabricate photonic devices inside commercial CE chips. The fabrication of single waveguides intersecting the channels allows one to perform LIF sensing. Waveguide splitters are used for multipoint sensing measurements. Finally, Mach-Zehnder interferometers are used for label-free sensing by means of refractive index changes detection.

Three-dimensional photonic devices fabricated by ultrafast lasers for optical sensing in lab-on-a-chip
Paper 7203-35 of Conference 7203
Date: Tuesday, 27 January 2009
Time: 2:40 PM – 3:00 PM

Author(s): Rebeca Martinez Vazquez, Roberto Osellame, Politecnico di Milano (Italy); Chaitanya Dongre, Hugo J. Hoekstra, Markus Pollnau, Univ. Twente (Netherlands); Hans H. van den Vlekkert, Lionix BV (Netherlands); Rob van Weeghel, Zebra Bioscience B.V. (Netherlands); Paul Watts, The Univ. of Hull (United Kingdom); Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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A lab-on-a-chip (LOC) is a device that incorporates in a single substrate the functionalities of a biological laboratory with micrometer dimensions. The next technological challenge of LOCs is direct on-chip integration of photonic functionalities. Ultrafast laser processing of the bulk of a dielectric material is a very flexible and simple method to produce photonic devices inside microfluidic chips for capillary electrophoresis (CE) or chemical microreactors. In this work we report on the use of femtosecond laser pulses to fabricate photonic devices inside commercial CE chips. The fabrication of single waveguides intersecting the channels allows one to perform LIF sensing. Waveguide splitters are used for multipoint sensing measurements. Finally, Mach-Zehnder interferometers are used for label-free sensing by means of refractive index changes detection.

High-peak/average power high-repetition rate
Paper 7193-65 of Conference 7193
Date: Wednesday, 28 January 2009
Time: 2:10 PM – 2:30 PM

Author(s): Sterling J. Backus, Xiaoshi Zhang, Gregory J. Taft, Hsiao-Hua Liu, Dirk Mueller, Henry C. Kapteyn, Margaret M. Murnane, Kapteyn-Murnane Labs. Inc. (United States)

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There is a growing need for next generation ultrafast sources operating at higher peak and average power levels and at wavelengths in the ultraviolet, visible, and infrared regions. For practical purposes, many of the applications will require repetition rates of 10-200 kHz, pulse energies of up to a few mJ at 10-20 kHz repetition rate, frequency conversion to new wavelengths via nonlinear conversion, and pulse durations of 50 fs or less to drive the nonlinear process. Here, we report on a new class of Ti:sapphire ultrafast laser designed to address this need. Higher pulse energies at 10–200 kHz repetition rates are generated by implementing cryogenic cooling and pulsed laser pumping of the amplifier stage. We have developed laser systems implementing this approach at the 10-20 W/ 1-100 kHz level. The performance of these systems and the potential for power-scaling will be discussed.

Charge dynamics in semiconductors and quantum wells from THz emission
Paper 7214-57 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 2:44 PM – 3:12 PM

Author(s): James N. Heyman, Macalester College (United States); Laura C. Bell, The Univ. of Utah (United States)

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We use ultrafast THz emission as a time-resolved probe in two studies: We find that THz emission from quantum wells depends only weakly on extrinsic carrier density, and that the intersubband coherence time remains ~3ps for photo-excitation up to 0.2eV above bandgap [1], consistent with THz emission driven by quantum beating rather than ultrafast field-screening. In addition, we observe the light-hole polaron resonance in THz cyclotron emission from GaAs and InP. This work was funded by the National Science Foundation under the NSF-RUI Program (DMR-0606181).
[1] L. Bell, et. al., APL 92, 142108 (2008)

Dynamic ultrafast laser beam tailoring for multispot photo-inscription of deep photonic devices in bulk transparent materials
Paper 7205-37 of Conference 7205
Date: Wednesday, 28 January 2009
Time: 4:10 PM – 4:30 PM

Author(s): Cyril Mauclair, Guanghua Cheng, Nicolas Huot, Eric Audouard, Lab. Hubert Curien (France); Arkadi Rosenfeld, Ingolf V. Hertel, Max-Born-Institut (Germany); Razvan I. Stoian, Lab. Hubert Curien (France)

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Femtosecond laser processing in transparent media can generate localized increase of the refractive index. Thus, by simple translation of the laser spot, light-guiding structures are achievable in the three dimensions. We report in the following a procedure of dynamic ultrafast laser beam tailoring for parallel photo inscription of deep photonic devices in a-SiO2. The wave front of the beam is controlled to achieve multi spot operation with real time adjustable separation of the spots. The procedure involves the control of the spatial phase of the beam with a spatial light modulator and is based on imaging of the laser spots.

Optical LAN technologies for the ultra-high definition video era
Paper 7235-4 of Conference 7235
Date: Thursday, 29 January 2009
Time: 9:30 AM – 10:00 AM

Author(s): Shu Namiki, National Institute of Advanced Industrial Science and Technology (Japan); Hiroshi Onaka, Tadashi Ikeuchi, Fujitsu Ltd. (Japan); Kimiyuki Oyamada, Japan Broadcasting Corp. (Japan); Ken Morito, Fujitsu Ltd. (Japan); Atsushi Sugitatsu, Mitsubishi Electric Corp. (Japan); Hiroshi Ishikawa, National Institute of Advanced Industrial Science and Technology (Japan); Tohru Asami, The Univ. of Tokyo (Japan)

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This invited talk will review the development of ultrafast all-optical LAN technologies, conducted by NEDO, Japan. First, we will provide an outlook for the energy issues of future network equipment, then point out the importance of optical circuit-switched networks, particularly for the future local area networks in the forthcoming ultra-high definition, or ‘Super Hi-vision’, video era. To realize ultrafast all-optical LAN, we argue that scalable network interface card technologies are the key. As specific development topics, 40G-CMOS based optical transceivers, picosecond all-optical switching using the inter-subband transition (ISBT) devices, high-temperature operating semiconductor optical amplifiers (SOA), and integrated high dynamic-range wavelength converters will be introduced.

Femtosecond pulse shaping for single molecule measurements
Paper 7185-26 of Conference 7185
Date: Sunday, 25 January 2009
Time: 9:45 AM – 10:05 AM

Author(s): Fernando D. Stefani, Institut de Ciències Fotòniques (Spain) and Ludwig-Maximilians-Univ. München (Germany); Daan Brinks, Niek F. van Hulst, Institut de Ciències Fotòniques (Spain)

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We developed a femtosecond pulse shaping scheme suitable for measurements at the nanoscale, therefore allowing new experiments on individual nano-systems and molecules. We demonstrate control over excitation probability of single molecules by shaping pulses on the femtosecond to picoseconds timescale. Unprecedented information about the ultrafast dynamics and spectral properties of the single molecules is obtained.

Optimizing CARS signal using coherent control methods
Paper 7183-25 of Conference 7183
Date: Monday, 26 January 2009
Time: 9:45 AM – 10:00 AM

Author(s): Vladimir S. Malinovsky, MagiQ Technologies, Inc. (United States)

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Recently we have shown that linearly chirped ultrafast pulses can be utilized to maximize CARS coherence. The method, uses the chirp sign variation at the central time, and gives robust adiabatic excitation of the resonant vibrational mode. Here we analyze influence of fast decoherence in the molecular samples and compare robustness and selectivity of the method to other excitation proposals. We demonstrate that the proposed adiabatic method allows achieving chemical sensitivity with high resolution and can be used to obtain CARS signal in molecular systems with coherence times of several hundred of femtoseconds.

Trapping gas bubble in water with tightly focused ultrashort laser pulses
Paper 7203-22 of Conference 7203
Date: Monday, 26 January 2009
Time: 2:00 PM – 2:20 PM

Author(s): Sergey Oshemkov, Pixer Technology Ltd. (Israel); Dvorkin Lev, Lasermax Engineering Ltd. (Israel); Vladimir Dmitriev, Pixer Technology Ltd. (Israel)

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We demonstrated that a gas bubble in water can be trapped in a tightly focused beam of a high repetition rate ultrafast laser. 200 fs width 100 kHz repetition rate laser pulses of a Ti-Sapphire amplifier focused by a 0.5 NA microsope objective were used for trap creation. The possibility of a trapped gas bubble manipulation by angle scanning of a laser beam or by translation motion of the beam focus point was shown. The trapping force was measured and the mechanism of trapping was suggested.

Nonlinear THz response of n-type GaAs
Paper 7214-31 of Conference 7214
Date: Monday, 26 January 2009
Time: 4:00 PM – 4:28 PM

Author(s): Michael Woerner, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)

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Using our novel high field THz source we performed various ultrafast experiments on n-type GaAs. Both nonlinear THz experiments driving resonantly the 1S-2P donor impurtiy transition and nonlinear transport experiments on free carriers in the conduction band of GaAs give new insights into the dynamics of localized and delocalized electrons surprisingly different to the well known linear Drude theory.

Industrial applications of a fiber-based, high-average-power picosecond laser
Paper 7201-15 of Conference 7201
Date: Monday, 26 January 2009
Time: 4:40 PM – 5:00 PM

Author(s): Colin Moorhouse, Coherent Scotland Ltd. (United Kingdom)

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With decreasing device dimensions, smaller, higher quality laser drilled features are required, hence, it is necessary to use shorter pulse durations. There has been significant research into ultrafast laser technology, and this report shows that recent developments have shown that a fibre oscillator and Diode Pumped Solid State (DPSS) amplifying technology can offer short picosecond pulse durations (~10ps) and high average power in an industrially-rugged package. This report outlines the advantages this technology offers for applications such as silicon via drilling, thin film patterning, drilling holes in metals and the machining of wide bandgap materials.

Real-time spectroscopy of a novel solid-state random laser
Paper 7212-20 of Conference 7212
Date: Tuesday, 27 January 2009
Time: 11:00 AM – 11:20 AM

Author(s): Sara Garcia-Revilla, Joaquín M. Fernández, Rolindes Balda, Univ. del País Vasco (Spain); Marcos Zayat, David Levy, Instituto de Ciencia de Materiales de Madrid (Spain)

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Here we report efficient random lasing in a ground powder of a novel solid-state material based on rhodamine 6G (Rh6G) doped nanoparticles embedded in a SiO2 matrix synthesized by the sol-gel technique. Basic properties of random lasing such as emission kinetics, emission spectrum, and threshold of stimulated emission are investigated by using real-time spectroscopy. The laser emission dynamics can be accurately described by a light diffusive propagation model. The device behaviour is close to a conventional ultrafast Q-switched laser, which is an interesting fact aimed to further applications.

Silicon based optical pulse shaping and characterization
Paper 7212-29 of Conference 7212
Date: Tuesday, 27 January 2009
Time: 4:10 PM – 4:40 PM

Author(s): Ozdal Boyraz, Xinzhu Sang, En-Kuang Tien, Univ. of California, Irvine (United States)

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The high-index contrast between the silicon core and silica cladding enable low cost chip-scale demonstration of all-optical nonlinear functional devices at relatively low pump powers due to strong optical confinement the in silicon waveguides. So far, broad ranges of applications from Raman lasers to wavelength converters have been presented. This presentation will highlight the recent developments on ultrafast pulse shaping and pulse characterization techniques utilizing the strong nonlinear effects in silicon. In particular, pulse compression due to two photon absorption and dual wavelength lasing

Femtosecond, nanosecond, and continuous-wave nonlinear optical properties of (H2)2SnPc, Sn(OH)2Pc, Sn(Cl)2Pc studied using Z-scan technique
Paper 7197-40 of Conference 7197
Date: Tuesday, 27 January 2009
Time: 6:00 PM

Author(s): Venugopal R. Soma, Univ. of Hyderabad (India)

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Phthalocyanines and their analogues/derivatives are macromolecules with large number of delocalized electrons possessing attractive third-order nonlinear optical properties with prominent applications in the areas of optical limiting and ultrafast all-optical switching. Here we present our results on the femtosecond, nanosecond, and continuous wave (cw) experimental nonlinear optical studies of Sn(H2)2Pc, Sn(OH)2Pc, and Sn(Cl)2Pc using the Z-scan technique

Femtosecond carrier dynamics in quasi-one-dimensional topological compounds
Paper 7214-52 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 11:11 AM – 11:39 AM

Author(s): Yasunori Toda, Hokkaido Univ. (Japan)

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Due to the recent progress of material science, quasi-one-dimensional (1D) materials provide an opportunity for investigating the influence of topology and dimensionality of materials on their optical and electrical properties. In this study, we report the phase transition properties of such quasi-1D compounds by utilizing an ultrafast optical spectroscopy. Photoinduced nonequilibrium carrier dynamics yield characteristic features around the phase transition temperatures. We also discuss the influence of topology and dimensionality on the phase transitions by using polarization and excitation energy dependences of the transient signals and their spatial characteristics.

Terahertz radiation coherently generated by acoustic waves
Paper 7215-1 of Conference 7215
Date: Wednesday, 28 January 2009
Time: 1:00 PM – 1:20 PM

Author(s): Michael R. Armstrong, Evan J. Reed, Lawrence Livermore National Lab. (United States); Ki-Yong Kim, Los Alamos National Lab. (United States); James H. Glownia, Dept. of Energy (United States); Edwin L. Piner, John C. Roberts, Nitronex Corp. (United States)

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Here we report the first observation of terahertz (THz) radiation coherently generated by an acoustic wave. Such emission is directly related to the time-dependence of the stress as the acoustic wave crosses an interface between materials of differing piezoelectric response. This technique is fundamentally distinct from optical approaches to strain wave measurement, enabling passive remote sensing of the dynamics of acoustic waves with ultrafast time resolution. The new mechanism presented here enables nanostructure measurements not possible using existing optical or x-ray approaches.

Harnessing second-order optical nonlinearities in compound semiconductors
Paper 7197-25 of Conference 7197
Date: Wednesday, 28 January 2009
Time: 3:50 PM – 4:20 PM

Author(s): Amr S. Helmy, Payam Abolghasem, Bhavin Bijlani, Univ. of Toronto (Canada)

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An overview of recent success in phase matching technologies of second order nonlinear optical processes in compound semiconductors will be reported. The technique used utilizes dispersion engineering in Bragg reflection waveguides (BRWs) or 1-dimensoinal photonic bandgap structures to achieve phase matching between the interacting waves. Nonlinear conversion efficiency matching what is achievable in PPLN is obtained ridge BRWs fabricated in the GaAs/AlGaAs. Most notable applications that would benefit from integrable ultrafast second order optical nonlinearities include monolithically integrated optical parametric oscillators, correlated photon pair sources and tunable frequency conversion monolithic arrays.

Two-color pump-probe studies of intraminiband relaxation in doped GaAs/AlGaAs superlattices
Paper 7214-60 of Conference 7214
Date: Wednesday, 28 January 2009
Time: 4:08 PM – 4:36 PM

Author(s): Dominik Stehr, Univ. of California, Santa Barbara (United States) and Forschungszentrum Dresden-Rossendorf e. V. (Germany); Martin Wagner, Harald Schneider, Manfred Helm, Forschungszentrum Dresden-Rossendorf e. V. (Germany); Aaron M. Andrews, Tomas Roch, Gottfried Strasser, Technische Univ. Wien (Austria)

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Two-color infrared pump-probe experiments are performed to investigate the miniband relaxation dynamics of electrons in doped GaAs/AlGaAs superlattices. By this technique we are able to separate the different contributions from inter- and intraminiband relaxation to the transient behavior after ultrafast excitation. The intraminiband relaxation is studied for different miniband widths, below and above the optical phonon energy of GaAs. For minibands wider than this critical value we find fast relaxation, nearly constant for different excitation intensities whereas for narrow minibands, a strong temperature and intensity dependence of the relaxation is found.

Nanoplasmonics
Date: Thursday, 29 January 2009
Time: 8:30 AM – 5:30 PM

Author(s): Mark I. Stockman, Georgia State Univ. (United States)

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Time-gated optical imaging to detect positive prostate cancer margins
Paper 7161B-204 of Conference 7161B
Date: Saturday, 24 January 2009
Time: 11:20 AM – 11:40 AM

Author(s): George Alexandrakis, Nimit L. Patel, Zi-Jing Lin, The Univ. of Texas at Arlington (United States); Jeffrey A. Cadeddu, The Univ. of Texas Southwestern Medical Ctr. at Dallas (United States); Hanli Liu, The Univ. of Texas at Arlington (United States)

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We will demonstrate the feasibility of using multi-modal time-gated optical imaging, i.e. time-resolved light reflectance and auto-fluorescence life-time imaging performed by an ultrafast ICCD (Intensified Charge-Coupled Device) imaging system to enable surgeons to detect positive tumor margins with high sensitivity and specificity over the entire resected prostate. Results from animal experiments as well as ex vivo human prostates will be presented that will demonstrate the feasibility of identifying differences in such optical signals between prostate cancer and control tissues. We will also discuss the use of classification algorithms to identify cancerous regions with greater accuracy than individual images would.

High volume confinement in two-photon fluorescence correlation spectroscopy with radially polarized light
Paper 7185-12 of Conference 7185
Date: Saturday, 24 January 2009
Time: 12:30 PM – 12:50 PM

Author(s): Denis A. Ivanov, Vladislav I. Shcheslavskiy, Iwan Märki, Ecole Polytechnique Fédérale de Lausanne (Switzerland); Marcel Leutenegger, Max-Planck-Institute for Biophysical Chemistry (Germany); Theo Lasser, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

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This paper presents theoretical and experimental investigation of a two-photon fluorescence correlation spectroscopy setup where a tightly focussed evanescent field is produced by total-internal reflection objective lens. The motivation of this investigation is to get attoliter detection volumes in FCS and expand the working range of single-molecule experiments to biologically relevant concentrations. The compatibility of a spatial light modulator with ultrafast lasers allowed us for the first time to take the advantage of nonlinear optical contrast mechanisms to suppress the side-lobe energy specific for radial polarization and reduce the effective excited volume compared to one-photon evanescent wave excitation in FCS.

Dynamics of photoexcited coherent phonon in Bi2Te3, Sb2Te3, and Bi2Te3/Sb2Te3 superlattice
Paper 7214-8 of Conference 7214
Date: Sunday, 25 January 2009
Time: 11:39 AM – 12:07 PM

Author(s): Xianfan Xu, Yaguo Wang, Purdue Univ. (United States)

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Non-equilibrium A1g longitudinal optical phonons in Bi2Te3, Sb2Te3, and Bi2Te3/Sb2Te3 superlattice are coherently excited by ultrafast pulses. Time resolved reflectivity measurements show vibrations around A1g optical phonon modes. The scattering rates due to interactions with incoherent phonon and interfaces at room temperature are derived by measuring the pump fluence dependent scattering rate of non-equilibrium A1g coherent phonon. The band structure is found to be transiently modified by the photoexcited carriers, and the energy coupling from photoexcited electrons to the lattice through coherent phonon vibration is more efficient and faster at higher pump fluence.

Study of high temperature stable FBGs fabricated in H2 loaded and unloaded SMF-28 fiber
Paper 7212-13 of Conference 7212
Date: Monday, 26 January 2009
Time: 3:00 PM – 3:20 PM

Author(s): Christopher W. Smelser, Dan Grobnic, Stephen J. Mihailov, Communications Research Ctr. Canada (Canada)

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High reflectivity fiber Bragg gratings are written with ultrafast infrared radiation in H2 loaded SMF-28 fiber that retain in excess of 60 percent of their index change at 1000 C using writing intensities below the damage threshold of the fiber. The reflectivity after annealing (>-15 dB transmission loss at the Bragg resonance) and index modulation ( ) in these devices is significantly higher than what can be achieved with UV devices such as Type II, Type IIA and chemical composition gratings. In this study the stability of these devices is compared to that of gratings fabricated in unloaded SMF-28 fiber.

Latest advances in ultra-fast laser sources for multi photon microscopy
Paper 7183-53 of Conference 7183
Date: Tuesday, 27 January 2009
Time: 10:30 AM – 10:45 AM

Author(s): Philip G. Smith, Newport Spectra-Physics (United States)

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The advent of compact, fully automated, and widely wavelength-tunable ultrafast oscillators has triggered an explosive growth in their use in a broad array of multiphoton imaging techniques. Over the past decade laser manufacturers have constantly improved the performance characteristics of these sources to meet the requirements of the user community. We will review the latest advances at Newport / Spectra-Physics in this field and discuss new ways of optimizing key parameters for efficient deep-tissue fluorescence generation, including turn-key, automated second order dispersion compensation that allows for optimization of the pulse width at the sample over a wide wavelength range, without compromising beam pointing and other critical beam parameters.

Transient behaviors of surface plasmon coupling with a light emitter
Paper 7214-45 of Conference 7214
Date: Tuesday, 27 January 2009
Time: 4:16 PM – 4:44 PM

Author(s): Wen-Hung Chuang, Jyh-Yang Wang, Yean-Woei Kiang, Chih-Chung Yang, National Taiwan Univ. (Taiwan)

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The ultrafast behaviors of the dipole couplings with a grating-perturbed resonant SPP, an LSP, and a grating-assisted SPP are numerically demonstrated. Either SPP or LSP coupling can be built in 3-7 fs. At a far-field position, the signal is received after a time delay of propagation plus a certain time period for the buildup of the dipole coupling system. The LSP coupling system decays through radiation and dissipation with time constants of 5-8 fs. The grating-assisted SPP coupling system decays in two stages, including the first stage of outward energy transport and the second stage of system relaxation.

Integration of micro-optics and microfluidics in a glass chip by fs-laser for opto-fluidic applications
Paper 7202-1 of Conference 7202
Date: Wednesday, 28 January 2009
Time: 8:20 AM – 8:50 AM

Author(s): Roberto Osellame, Rebeca Martinez Vazquez, Paolo Laporta, Roberta Ramponi, Giulio Cerullo, Politecnico di Milano (Italy)

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The combination of microoptics and microfluidics, also known as optofluidics, is raising an increasing interest. Recently, directly buried high quality waveguides and microfluidic channels have been fabricated by femtosecond lasers. The main advantage of this technique is its three-dimensional capability providing high flexibility in intersecting the optical and fluidic structures.
In this work, a few optofluidic devices based on this technology will be discussed. On one hand, the integration of an ultrafast optical switch is demonstrated. On the other hand, the integration of optical waveguides and Mach-Zehnder interferometers for sensing of biomolecules in a capillary electrophoresis chip will be presented.

Compact cavity dumped broadband laser oscillator
Paper 7193-63 of Conference 7193
Date: Wednesday, 28 January 2009
Time: 1:30 PM – 1:50 PM

Author(s): Estelle Coadou, Coherent, Inc. (United States); D. Neumeyer, APE GmbH (Germany); Bojan Resan, Coherent, Inc. (United States); Ingo Rimke, APE GmbH (Germany)

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Recent development of optically-pumped semiconductor laser (OPSL) technology provide a Ti:sapphire pump source that reduces cost and complexity while maintaining a high standard of performance and reliability. In this paper we report on the performance of a compact (930 x 330 x 170 mm³), cavity-dumped ultrafast Ti:Sapphire laser oscillator pumped by an (OPSL) and using negative dispersion mirrors. The system generates broadband pulses of up to 30nJ pulse energy at 1 MHz repetition rate, bandwidth of >75nm, and compressed pulse duration of <20fs. The system is rep-rate tunable from single-shot to 10MHz.

Cavity quantum electrodynamics in the ultrastrong coupling regime
Paper 7214-1 of Conference 7214
Date: Sunday, 25 January 2009
Time: 8:00 AM – 8:28 AM

Author(s): Cristiano Ciuti, Univ. Paris 7-Denis Diderot (France)

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Several experiments have recently demonstrated the strong coupling between a planar microcavity photon mode and an intersubband transition in doped quantum wells[1-4]. Research in this new field is dealing with several interesting topics, including the electrical control[2], detection[3] and injection[4,5] of intersubband cavity polaritons, as well as the ultrastrong coupling cavity quantum electrodynamics. Indeed, it has been shown theoretically that in this kind of semiconductor microcavities one can reach an unconventional ultra-strong coupling regime[6], i.e. the vacuum Rabi frequency can be comparable to the transition frequency. In this unusual regime, the quantum ground state is a squeezed vacuum containing correlated photon pairs[6]. If the cavity parameters are time-independent, the photon pairs in the quantum ground state are unobservable outside. Instead, a non-adiabatic time-modulation of the cavity vacuum is able to release the virtual photon pairs and produce a radiation out of the quantum vacuum[6,7]. Promisingly, recent ultrafast experiments[8] have demonstrated that it is possible to achieve a non-adiabatic modulation of ultrastrong light-matter coupling. In this invited talk, I will review predictions[6,7] for the quantum vacuum radiation phenomena in the ultrastrong coupling regime, pointing out fascinating perspectives in this new research field.

Monitoring changes of proteins and lipids by Raman spectroscopy in laser tissue welding
Paper 7175-3 of Conference 7175
Date: Monday, 26 January 2009
Time: 8:50 AM – 9:10 AM

Author(s): Cheng-Hui Liu, Wubao B. Wang, Alexandra N. Alimova, Vidyasagar Srirmoju, Vladimir Kartazayev, Robert R. Alfano, City College/CUNY (United States)

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Monitoring changes of proteins and lipids by Raman spectroscopy in laser tissue welding

C.-H. Liu, W.B. Wang, S.A. Alimova, V. Sriramoju,
V. Kartazayev and R.R. Alfano,
Institute for Ultrafast Spectroscopy and Lasers, Department of Physics, the City College and of
the City University of New York, New York, New York 10031
The changes of Raman spectrum of porcine aorta tissue before and after laser tissue welding by 1445nm laser beam were studied. Raman spectra were measured for normal and welded tissue in both tunica adventitia and intima sides. The vibrational modes at the peak and shoulder positions (1256 cm-1 and 1301 cm-1) of amide III in the normal tissue were found to be shifted to 1269cm-1 and 1327cm-1, respectively, in the welded adventitia side tissue. The Raman characteristic spectra were analyzed as a composite of standard chemical assays using the linear regression fitting method. The relatively composition changes of proteins (Collagen types I, III, V and Elastin) and lipids for welded tissue were modeled as compared with the normal tissue. Collagen type III relatively decreased and others relatively increased in the adventitia side of welded tissue. These results are consisted with fluorescence spectral study on tissues previously reported.


Submit to: SPIE Photonics West 2009, 24-29 January 2009, San Jose, California, USA
Section: Optical Interactions with Tissue and Cells XX (BO201),
Topics: Laser welding and soldering of tissue