Impact of optical frequency comb noise on free-running dual-comb spectroscopy.

Dual-comb spectroscopy (DCS) has emerged as an indispensable optical technique for probing broadband optical spectra of molecular species with high resolution. To better understand the impact of phase noise in free-running DCS implementations, we investigate the effects of timing jitter and carrier-envelope phase noise on the shape of Lorentzian absorption lines extracted from single-shot interferograms. An analysis of linewidth broadening and fluctuations of the center frequency allows us to quantify the amount of optical frequency comb noise that significantly distorts absorption features. The theory validated through simulation should help predict the fidelity of dual-comb-based absorption measurements with relevance for precise molecular and atomic spectroscopy.