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Proceedings Paper

Wavelength-agile coherent tunable mid-IR ZGP-OPO source and its applications
Author(s): Katsuhiko Miyamoto; Kazi Monowar Abedin; Hiromasa Ito
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Paper Abstract

We report the demonstration of a wavelength-agile coherent tunable mid-infrared (IR) ZnGeP2 (ZGP) optical parametric oscillator (OPO). The mid-IR wavelength was tuned by varying the KTiOPO4 (KTP) OPO pumping wavelength, while the ZGP crystal angle remained fixed. The wavelength of pump OPO was controlled by changing the KTP crystals angle using a Galvano-optical beam scanner. Our mid-IR source can jump to a arbitrary wavelength without scanning through the intermediate wavelengths. A nonlinear optical crystal ZGP is suitable for OPOs in the mid-IR region. In most cases of mid-IR light generation using an OPO, the wavelength tuning is achieved by controlling the phase-matching angle or temperature of the nonlinear optical crystal. However, there are several disadvantages of this method including the walk-off angle, beam pass instability, refraction losses due to the high refractive index of ZGP (n~3.1), slow tuning rate, and so forth. Therefore, we developed a 2-&mgr;m-band pump-wavelength tunable mid-IR ZGP-OPO source. The mid-IR wavelength from the ZGP-OPO could be tuned from 5 to 9.8 &mgr;m, when the pump wavelength was controlled from 1.95 to 2.3 &mgr;m. The output pulse energy at 8&mgr;m was 1.3mJ/pulse at repetition rate of 30Hz. As an application of random wavelength accessibility, we could achieve the real-time measurement of phase change (solidification) of candle wax by measuring the change of absorption at two arbitrary wavelengths. We selected two wavelengths on the spectrum where significant changes of absorption upon solidification were detected and performed two-wavelength absorption measurements as the sample is allowed to cool from melted state.

Paper Details

Date Published: 8 May 2007
PDF: 9 pages
Proc. SPIE 6582, Nonlinear Optics and Applications II, 65820U (8 May 2007); doi: 10.1117/12.723240
Show Author Affiliations
Katsuhiko Miyamoto, Tohoku Univ. (Japan)
Tera-Photonics Lab. (Japan)
Kazi Monowar Abedin, Tohoku Univ. (Japan)
Hiromasa Ito, Tohoku Univ. (Japan)
Tera-Photonics Lab. (Japan)

Published in SPIE Proceedings Vol. 6582:
Nonlinear Optics and Applications II
Mario Bertolotti, Editor(s)

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