2019年9月
Terahertz differential absorption spectroscopy using multifurcated subnanosecond microchip laser
APPLIED PHYSICS LETTERS
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- 巻
- 115
- 号
- 12
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1063/1.5119411
- 出版者・発行元
- AMER INST PHYSICS
Using spectral multifurcated oscillations in a passively Q-switched microchip laser, we demonstrate frequency-domain differential absorption spectroscopy in the terahertz (THz) frequency region. Within a single quasi-continuous-wave (QCW) excitation, a microchip laser comprising a 7-mm-long Nd:YAG/Cr:YAG composite ceramic provides up to three subnanosecond pulses with a 1064-nm wavelength and a 50-Hz QCW repetition rate. We have observed that the longitudinal mode of double and triple pulses shows stable bifurcation and trifurcation, respectively, induced by a spatial hole burning effect within the laser cavity. These pulses are directly used to drive an injection-seeded THz-wave parametric generator based on a MgO-doped LiNbO3 crystal, thereby generating up to three monochromatic, self-frequency-switched THz-wave pulses separated from each other in frequency by a free spectral range of the laser cavity. By precisely tuning one of the THz-wave frequencies to the gas absorption line, multifurcated THz-wave pulses facilitate the measurement of differential absorption signals every 20 ms without any active frequency modulation. We also show that first- and second-order derivative spectra of gas absorption can be derived from a single frequency sweep of multifurcated pulses without a reference spectrum and computational derivation. Our approach paves the way toward realization of a THz differential absorption lidar for use in fast gas sensing applications.
- リンク情報
- ID情報
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- DOI : 10.1063/1.5119411
- ISSN : 0003-6951
- eISSN : 1077-3118
- Web of Science ID : WOS:000487038900005