Quasi-real-time dual-comb spectroscopy with 750-MHz Yb:fiber combs

We present quasi-real-time dual-comb spectroscopy (DCS) using two Yb:fiber combs with similar to 750 MHz repetition rates. A computational coherent averaging technique is employed to correct timing and phase fluctuations of the measured dual-comb interferogram (IGM). Quasi-real-time phase correction of 1-ms long acquisitions occurs every 1.5 seconds and is assisted by coarse radio frequency (RF) phase-locking of an isolated RF comb mode. After resampling and global offset phase correction, the RF comb linewidth is reduced from 2(X) kHz to similar to 1 kHz, while the line-to-floor ratio increases 13 dB in power in 1 ms. Using simultaneous offset frequency correction in opposite phases, we correct the aliased RF spectrum spanning three Nyquist zones, which yields an optical coverage of similar to 180 GHz around 1.035 mu m probed on a sub-microsecond timescale. The absorption profile of gaseous acetylene is observed to validate the presented technique. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This study presents quasi-real-time dual-comb spectroscopy using two Yb:fiber combs with approximately 750 MHz repetition rates. A computational coherent averaging technique is employed to correct timing and phase fluctuations of the measured dual-comb interferogram. Quasi-real-time phase correction is performed every 1.5 seconds, assisted by coarse radio frequency phase-locking. After resampling and global offset phase correction, the RF comb linewidth is reduced and the line-to-floor ratio increases. Simultaneous offset frequency correction is used to correct the aliased RF spectrum, achieving optical coverage of approximately 180 GHz.