Dual-comb Yb:CALGO laser with a polarization multiplexed cavity and pump

Abstract

Single-cavity dual-comb lasers are considered appealing solutions for dual-comb spectroscopy. However, achieving a wide and flexible adjustment of repetition rate differences in the dual-combs with common bulk gain crystals remains challenging. Here, we report a dual-comb Yb:CALGO laser with a polarization multiplexed cavity and pump with two alternative configurations. The repetition rate difference of our dual-comb laser can be easily tuned from zero up to the MHz range. The standard deviation of the repetition rate difference is suppressed to be 0.4 Hz over 5 minutes, though the drift of the repetition rate of each comb is as large as closing to 80 Hz. We achieve simultaneous operations of two combs at approximately 1044 nm with pulse durations of 188 fs and 269 fs, and average powers of 1.6 W and 1.5 W, respectively. We demonstrate the capabilities of this system by utilizing the free-running setup to measure dual-comb spectra and perform asynchronous optical sampling on a saturable absorber. This work provides an alternative way to achieve a simple, compact, all-solid-state dual-comb femtosecond laser with flexible control over the repetition rate difference.