Mechanical sharing dual-comb fiber laser based on an all-polarization-maintaining cavity configuration

We present a mechanical sharing, dual-comb fiber laser based on an all-polarization-maintaining cavity configuration and a nonlinear amplifying loop mirror mode-locking mechanism. This simple setup yields dual-optical frequency combs with a high level of mutual coherence without active servo control. We realized a high relative stability with a standard deviation of 0.27 Hz and a relative beat note between the dual-frequency combs with a full-width at half-maximum of ∼50Hz. Dual-frequency combs were found to have high relative stability and mutual coherence owing to passive common-mode noise suppression using a mechanical sharing laser cavity. This laser configuration can significantly simplify dual-comb spectroscopy.