Open AccessInterferogram-based determination of the absolute mode numbers of optical frequency combs in dual-comb spectroscopy
Author(s) -
Tatsuhiro Fukuda,
Masaya Okano,
Shinichi Watanabe
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.431104
Subject(s) - hitran , optics , spectroscopy , physics , absorption spectroscopy , quantum mechanics
Dual-comb spectroscopy (DCS), which uses two optical frequency combs (OFCs), requires an accurate knowledge of the mode number of each comb line to determine spectral features. We demonstrate a fast evaluation method of the absolute mode numbers of both OFCs used in DCS system. By measuring the interval between the peaks in the time-domain interferogram, it is possible to accurately determine the ratio of one OFC repetition frequency (f rep ) to the difference between the f rep values of the two OFCs (Δf rep ). The absolute mode numbers can then be straightforwardly calculated using this ratio. This method is applicable to a broad range of Δf rep values down to several Hz without any additional instruments. For instance, the minimum required measurement time is estimated to be about 1 s for Δf rep ≈ 5.6 Hz and f rep ≈ 60 MHz. The optical frequencies of the absorption lines of acetylene gas obtained by DCS with our method of mode number determination shows good agreement with the data from the HITRAN database.