Polarization-multiplexed single-cavity dual combs and application in absorption spectroscopy

Dual-comb spectroscopy is a kind of competitive tool for realizing high-resolution and wide-bandwidth absorption spectroscopy. The development of compact dual-comb systems generated from a single laser effectively simplified the structure of dual-comb spectroscopy. Herein, we demonstrate a simple measurement of absorption spectroscopy based on an all-fiber single-cavity dual-comb laser. The free-running dual combs were generated by the polarization-multiplexed mechanism with a 32.6-MHz repetition rate and 250-Hz repetition rate difference. The dual-comb spectroscopy can operate without a servo locking system since the two combs were generated synchronously, in which the jitters can be offset by each other resulting in naturally high coherence. Tooth-resolved dual-comb spectroscopy was enabled by a computational correction algorithm. Weak absorption features of hydrogen cyanide were extracted and in line with the HITRAN database. Such kind of dual-comb spectrometer paves the way for the realization of low-complexity and high-precision absorption spectroscopy.