Saturday, June 1, 2019

Abstract-Combination of lock-in detection with dual-comb spectroscopy



Hidenori Koresawa, Kyuki Shibuya,  Takeo Minamikawa,  Akifumi Asahara,  Kaoru Minoshima,  Takeshi Yasui

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10925/109251A/Combination-of-lock-in-detection-with-dual-comb-spectroscopy/10.1117/12.2509619.short?SSO=1


Dual-comb spectroscopy (DCS) is a powerful tool for gas spectroscopy due to high resolution, high accuracy, broadband spectral coverage, and rapid data acquisition, based on optical frequency comb (OFC) traceable to a frequency standard. In DCS, after a temporal waveform of interferogram is acquired in time domain, the corresponding mode-resolved OFC spectrum is obtained by fast Fourier transform (FFT) calculation of the acquired interferogram. However, FFT calculation of huge-sized temporal data spends significantly longer time than the acquisition time of interferogram, making it difficult to response the transient signal change. In this article, we demonstrate frequency-domain DCS by a combination of DCS with lock-in detection (LID), namely LID-DCS. LID-DCS directly extracts an arbitrary OFC mode from a vast number of OFC modes without the need for FFT calculation by the synchronous detection at a LID reference frequency while maintaining high resolution and high accuracy. Usefulness of LID-DCS is demonstrated in rapid monitoring of transient signal change and spectroscopy of hydrogen cyanide gas by comparing with usual DCS.
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