2004 Fiscal Year Final Research Report Summary
Development of real time terahertz imaging system using optical mixing effect
| Project/Area Number |
14205011
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TANIUCHI Tetsuo TOHOKU UNIVERSITY, INSTITUTE OF MULTIDISCIPLINARY RESEARCH FOR ADVANCED MATERIALS, ASSOICIATE PROFESSOR, 多元物質科学研究所, 助教授 (80260446)
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| Project Period (FY) |
2002 – 2004
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| Keywords | terahertz / nonlinear optics / organic material |
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| Research Abstract |
Frequency conversion between optical and terahertz (THz) waves using nonlinear optical mixing in an organic DAST and GaP crystal was investigated theoretically and experimentally. Widely tunable THz waves ranging from 2 to 30 THz were generated from DAST crystals using a dual-wavelength optical parametric oscillator (OPO) with two KTiOPO_4 crystals as the input light source. The OPO has a tunable range from 1340 to 1550 nm and is pumped by a frequency-doubled, Q-switched Nd : YAG laser with a pulse duration of 12 ns. The THz output energy exceeding 550 nJ (peak power : 46 W) at 11.3 THz was obtained with a 1-mm-thick DAST crystal. Sub-THz waves in the range of 0.3-3 THz were also generated using an improved dual-wavelength OPO near 990 nm in combination with 2-mm-thick DAST and 15-mm-thick GaP crystals.
Frequency conversion from THz-wave to optical wave can be achieved by sum frequency generation (SFG). Phase-matching conditions were studied for DAST, GaP, ZnTe and GaAs crystals. Sum frequency optical wave at 1400nm was generated from DAST crystal by mixing the THz wave at 11.3 THz and the optical wave at 1478 nm. These THz system consisting of the tunable THz source and the SFG detection system could potentially be used for real-time THz-imaging, THz-ranging, and spectroscopic applications.
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