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
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).
Contact:
(518) 276-3079
zhangxc@rpi.edu
Home Page: http://www.rpi.edu/~zhangxc
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
Abstract:
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.
Keywords:
terahertz, photoconductive antenna, laser noise, amplitude modulation,
free-space electro-optic sampling
*E-mail address: t-yasui@me.es.osaka-u.ac.jp
--------------------------------------------------------------------------------
References:
D. M. Mittleman, R. H. Jacobsen and M. C. Nuss: IEEE J. Sel. Top. Quantum
Electron. 2 (1996) 679.
T. Löffler, T. Bauer, K. J. Siebert, H. G. Roskos, A. Fitzgerald and S. Czasch:
Opt. Express 9 (2001) 616.
R. H. Jacobsen, D. M. Mittleman and M. C. Nuss: Opt. Lett. 21 (1996) 2011.
D. H. Auston, K. P. Cheung and P. R. Smith: Appl. Phys. Lett. 45 (1984)
284[AIP].
Q. Wu and X.-C. Zhang: Appl. Phys. Lett. 67 (1995) 3523[AIP].
D. R. Walker, D. W. Crust, W. E. Sleat and W. Sibbet: IEEE J. Quantum Electron.
28 (1992) 289[CrossRef].
Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C.
Zhang and J. F. Federici: Appl. Phys. Lett. 73 (1998) 444[AIP].
V. Iyer, B. E. Losavio and P. Saggau: J. Biomed. Opt. 8 (2003) 460.
G. Zhao, R. N. Schouten, N. van der Valk, W. Th. Wenckebach and P. C. M. Planken:
Rev. Sci. Instrum. 73 (2002) 1715[AIP].
T. Yasui, T. Mitsunari and T. Araki: Abst. 9th International Workshop on
Femtosecond Technology (The Femtosecond Technology Research Association,
Tsukuba, 2002) p. 183.
Y. C. Shen, P. C. Upadhya, E. H. Linfield, H. E. Beere and A. G. Davies: Appl.
Phys. Lett. 83 (2003) 3117[AIP].
N. Zamdmer, Q. Hu, K. A. Mclntosh and S. Verghese: Appl. Phys. Lett. 75 (1999)
2313[AIP].
M. Tani, S. Matsuura, K. Sakai and S. Nakashim: Appl. Opt. 36 (1997) 7853.
S. Matsuura, M. Tani and K. Sakai: Appl. Phys. Lett. 70 (1997) 559[AIP].
S. V. Frolov and Z. V. Vardeny: Rev. Sci. Instrum. 69 (1998) 1257[AIP].
S. P. Mickan, D. Abbott, J. Munch and X.-C. Zhang: Fluctuation Noise Lett. 2
(2002) R13.