Del Mar Photonics

Terahertz Spectroscopy and Microscopy

Teraherts products from Del Mar Photonics

Pacifica THz Time Domain Spectrometer

THz Photoconductive Antenna - buy from stock

Generation of 10 µJ ultrashort terahertz pulses by optical rectification using
Wedge TiSapphire Multipass Amplifier

Crystals for THz generation:
Gallium Phosphor GaP 110-cut crystals for THz applications
GaSe is used as infrared nonlinear crystal and for THz applications GaSe crystal, Z-cut, 10x10x1 mm
ZnTe crystals for THz generation  ZnTe crystal, 10x10x0.5 mm, 110-cut 

Photoconductive Antenna for terahertz waves
iPCA - interdigital Photoconductive Antenna for terahertz waves

THz detectors: Golay cell and LiTaO3 piroelectric detectors

Terahertz research references

Xi-Cheng Zhang

Terahertz Optics Sensing
Zhang’s work with time-domain THz spectroscopy systems holds promise for diagnostics of materials such as semiconductors and biomolecules. THz time-domain spectroscopy uses short pulses of broadband THz radiation, typically generated using ultrafast laser pulses. The transmitted THz electric field is measured coherently, which provides both high sensitivity and time-resolved phase information.

Terahertz Optics Imaging
Zhang’s interest in THz wave imaging is a result of the availability of phase-sensitive spectroscopic images. These images, called “functional images,” are ideal for dry dielectric substances including paper, plastics, and ceramics. Zhang’s research centers on two-dimensional THz wave imaging through free-space electro-optic detection and on THz ray, or T-ray, imaging for probing the dielectric properties of three-dimensional structures.

Selected Publications:

Xu Xie, Jingzhou Xu, and X.-C. Zhang , “Terahertz generation from CdTe crystal characterized by excitation frequency,” Optics Letters, 31 978 (2006).

Xu Xie, Jianming Dai, and X.-C. Zhang , “Coherent control of THz wave generation in ambient air,” Physics Review Letters, 96 075005 (2006).
J.Z. Xu and X.-C. Zhang , “THz wave reciprocal imaging,” Applied Physics Letters, 88, 151107 (2006).

Lantao Guo, Ying Hu, Yan Zhang, Cunlin Zhang, Yunqing Chen and X.–C. Zhang, “Vibrational spectrum of γ-HNIW investigated using terahertz time-domain spectroscopy,” Optical Express, 14, 3654, (2006).

Jianming Dai, Xu Xie , and X.-C. Zhang , “Detection of broadband terahertz waves with laser-induced plasma in gases,” Physics Review Letters, 97, 103903 (2006).

Hua Zhong, Albert Redo-Sanchez, and X.-C. Zhang , “Identification and classification of chemicals using terahertz reflective spectroscopic focal-plane imaging system,” Optical Express 14, 9130-9141, (2006).

Hua Zhong, Nicholas Karpowicz, and X.-C. Zhang , “Terahertz emission profile from laser-induced air plasma," Applied Physics Letters 88, 261103 (2006).

Haibo Liu and X.-C. Zhang , "Dehydration kinetics of D-glucose monohydrate studied using THz time-domain spectroscopy", Chemical Physics Letters 429, 229–233 (2006).

Hai-Bo Liu, Yunqing Chen, Glenn J. Bastiaans, and X.-C. Zhang, “Detection and identification of explosive RDX by THz diffuse reflection spectroscopy,” Optics Express, 14, 415 (2006).

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Dependence of Terahertz Electric Fields on Electric Bias and Modulation Frequency in Pulsed Terahertz Emissions from Electrically-Modulated Photoconductive Antenna Detected with Free-Space Electro-Optic Sampling.

Takeshi Yasui* and Tsutomu Araki Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan  (Received October 25, 2004; revised December 22, 2004; accepted January 11, 2005; published April 8, 2005)

Japanese Journal of Applied Physics
Vol. 44, No. 4A, 2005, pp. 1777-1780

We investigated the dependence of terahertz (THz) electric fields on electric bias and modulation frequency in the pulsed THz emissions from electrically modulated photoconductive antennas detected with free-space electro-optic sampling. The linear dependence of the THz electric field on the electric bias achieves distortion-free modulation of the THz pulse even for deep modulation. We confirmed that the signal-to-noise ratio in free-space electro-optic sampling of the THz pulse is strongly affected by the 1/f noise characteristics of the mode-locked laser, and is improved effectively by increasing the modulation frequency. The resulting signal-to-noise ratio was 4,900 in THz radiation power at 0.1 THz using an audio-frequency lock-in amplifier with a time constant of 1 ms and modulation frequency of 100 kHz. The proposed method will be a powerful tool for real-time or highly sensitive THz measurements.

terahertz, photoconductive antenna, laser noise, amplitude modulation, free-space electro-optic sampling

*E-mail address:


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