Dual electro-optic frequency comb spectroscopy using pseudo-random modulation.

An approach for dual-comb spectroscopy using electrooptic (EO) phase modulation is reported. Maximum-length pseudo-random binary sequences allow for energy-efficient and flexible comb generation. Self-correction of interferograms is shown to remove relative comb drifts and improve mutual coherence, even for EO combs derived from the same laser source. Methane spectroscopy is reported over a similar to 10 GHz spectral range, limited by the modulators' bandwidth. The potential of a simple EO comb instrument is demonstrated to rapidly quantify atmospheric methane emissions with ppb precision over 1 km. (C) 2019 Optical Society of America