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Del Mar Photonics
Ti:Sapphire laser
helps Physical Optics Corporation in Phase I and Phase II Army awards.
To address the U.S. Army need for new techniques for detecting concealed
explosives, Physical Optics Corporation (POC) proposes a new 100 m standoff
Terahertz Spectroscopic Radar (TSR) which uses terahertz (THz) molecular
spectroscopy to detect the unique THz absorption wavelength signature of an
explosive's outgassed material. This design exhibits the most decisive
identification pattern of explosives, whose molecular vibration modes lie in the
THz region. To detect these specific explosive identifiers, TSR's innovative
design analyzes the retroreflected THz signals from targets rather than the
transmitted THz signals common to the conventional spectroscopy performed inside
a laboratory. The TSR design combines a wideband (1-20 THz) transmitter and a
receiver spectrometer, built on a mobile station. Using a high-quality
submillimeter wave radar to send high rep-rate (~100 MHz) THz probing pulses, we
can identify not only the explosive but also the location of the target with
spatial resolution better than 0.03 mm since our radar pulsewidth is faster than
100 femtosecond (fs). The average power of our source is exceptionally high
(~100 W) compared with any other THz sources. In Phase I we will build a
preliminary TSR prototype, while Phase II will focus on a full engineering
prototype.
Ti:Sapphire laser for THz spectroscopic radar.
Paper to be presented at SPIE Defense Security and Sensing 2009
Physical Optics Corporation (POC) studied intense terahertz (THz) generation through optical rectification in bulk low-temperature growth GaAs (LG-GaAs) and quasi-phase-matched orientation pattern GaAs (OP-GaAs). POC performed simulations based on one-dimensional coupled propagation equations of THz and optical fields and conducted experimental tests. The results show that a LG-GaAs crystal with 0.5mm-thick under the excitation of a compact all-fiber femtosecond laser (76 MHz, 100 fs, 100 mW, 800 nm) can generate wide frequency range from 0.1 to 8.2 THz. The enhanced conversion efficiency was found for OP-GaAs crystal that can generate an average THz power of several milliwatts. Both theoretical and experimental results show that average THz output power is proportional to the energy fluence of the excitation source rather than the laser power for ultra-short pulse source. These achievements provide an effective approach to increase THz output power. Paper to be presented at SPIE Defense Security and Sensing 2009
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Del Mar Photonics, Inc.
4119 Twilight Ridge
San Diego, CA 92130
tel: (858) 876-3133
fax: (858) 630-2376
Skype: delmarphotonics
sales@dmphotonics.com