Spectral distortion of dual-comb spectrometry due to repetition rate fluctuationProject supported by the State Key Laboratory of Precision Measurement Technology & Instruments of Tsinghua University and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205147)

• Published in: Chinese physics B Vol. 25; no. 4
• Main Authors: Yang, Hong-Lei, Wei, Hao-Yun, Li, Yan
• Format: Journal Article
• Language: English
• Published: IOP Publishing 20.02.2016
• Subjects: Infrared spectra; molecular spectra; optical frequency comb
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/25/4/044207

Dual-comb spectrometry suffers the fluctuations of parameters in combs. We demonstrate that the repetition rate is more important than any other parameter, since the fluctuation of the repetition rate leads to a change of difference in the repetition rate between both combs, consequently causing the conversion factor variation and spectral frequency misalignment. The measured frequency noise power spectral density of the repetition rate exhibits an integrated residual frequency modulation of 1.4 Hz from 1 Hz to 100 kHz in our system. This value corresponds to the absorption peak fluctuation within a root mean square value of 0.19 cm−1 that is verified by both simulation and experimental result. Further, we can also simulate spectrum degradation as the fluctuation varies. After modifying misaligned spectra and averaging, the measured result agrees well with the simulated spectrum based on the GEISA database.