
Proceedings Paper
Coherent detection of multicycle terahertz pulses generated in periodically inverted GaAs structuresFormat | Member Price | Non-Member Price |
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Paper Abstract
Narrow-band, multi-cycle terahertz (THz) pulses have been generated in the pre-engineered domain structure
of periodically-poled lithium niobate (PPLN) crystals. The mechanism for THz generation is quasi-phase-matching
(QPM) optical rectification. Recently, THz generation of high conversion efficiency in a new material,
QPM GaAs, were demonstrated using mid-IR femtosecond pulses. GaAs has several advantages for QPM
THz wave generation, as compared to PPLN. First, it is highly transparent at THz frequencies (absorption
coefficient below 1.5 THz < 1 cm-1). Second, the mismatch between the optical group velocity and THz
phase velocity is much smaller: the corresponding group (ng) and refractive (n) indices are ng=3.431 at 2&mgr;m
and n=3.61 at 1 THz. In this work, we report on generation of THz wave packets in three different types of
QPM GaAs, combined with their coherent detection using two-color THz time-domain spectroscopy. The QPM
GaAs structures are optically-contacted GaAs, diffusion-bonded GaAs, and all-epitaxially-grown orientation patterned
GaAs. The QPM optical rectification in GaAs is a nonresonant mechanism, as opposed to widely used
photoconductive antenna technique in GaAs, where THz radiation is produced via ultrafast charge transport
caused by photoexcitation with femtosecond laser pulses of the near-IR range. In order to avoid linear and
two-photon absorption in GaAs, we use 2&mgr;m femtosecond pulses to generate THz pulses. We measure the THz
waveforms via electro-optic sampling in ZnTe using 0.8&mgr;m probe pulses. The corresponding power spectra are
also measured by a THz Michelson interferometer. Frequency tunability in the range 0.8-3 THz is achieved with
several structure periods.
Paper Details
Date Published: 14 February 2007
PDF: 8 pages
Proc. SPIE 6455, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VI, 64550G (14 February 2007); doi: 10.1117/12.699411
Published in SPIE Proceedings Vol. 6455:
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VI
Peter E. Powers, Editor(s)
PDF: 8 pages
Proc. SPIE 6455, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VI, 64550G (14 February 2007); doi: 10.1117/12.699411
Show Author Affiliations
Yun-Shik Lee, Oregon State Univ. (United States)
W. C. Hurlbut, Oregon State Univ. (United States)
K. L. Vodopyanov, Stanford Univ. (United States)
W. C. Hurlbut, Oregon State Univ. (United States)
K. L. Vodopyanov, Stanford Univ. (United States)
M. M. Fejer, Stanford Univ. (United States)
V. G. Kozlov, Microtech Instruments, Inc. (United States)
V. G. Kozlov, Microtech Instruments, Inc. (United States)
Published in SPIE Proceedings Vol. 6455:
Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VI
Peter E. Powers, Editor(s)
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