Dual-comb generation from a single laser source: principles and spectroscopic applications towards mid-IR-A review

Dual-comb spectroscopy (DCS) is a promising approach for real time, high precision, and high sensitivity Fourier-transform spectroscopy. DCS requires a pair of tightly phase-locked optical frequency combs (OFCs). The intrinsic complexity hinders practical application of this technique. Recently, there is a new trend of generating a pair of OFCs with slightly different repetition rate from a single laser cavity, known as dual-comb lasers. Shared laser cavity cancels common-mode technical noises passively and mutual coherence between the OFCs is well maintained. Given that the cumbersome phase locking systems are avoided, dual-comb lasers provide an attractive alternative to a pair of independent OFCs. In this review paper, we summarize the latest laser cavity multiplexing schemes that allow dual-comb generation in solid state lasers, fiber lasers as well as in on-chip waveguide lasers. Their noise characteristics as well as the impact on the reachable performances in dual-comb applications, have been thoroughly discussed. Next, the recent progress of DCS based on single dual-comb lasers have been presented, unfolding the advantages of implementing ultrahigh precision molecular spectroscopic experiments with a simple setup. In particular, DCS towards mid-IR fingerprint region is emphasized. Finally, there is an outlook on the new trends of single dual-comb lasers working in mid-IR. The advances in DCS by combining multiple-comb mode-locking technique and recent emerging precision spectroscopic detection methods are also expected.