Polarization-multiplexed dual-comb Yb:fiber laser with dual-phase-biased nonlinear amplifying loop mirror

• A polarization-multiplexed dual-comb Yb:fiber laser is realized using a dual-phase-biased nonlinear amplifying loop mirror. • The two combs share the entire fiber part of the cavity, enabling passive common-mode noise suppression. • A reflection-type dual-phase-bias module allows flexible tuning of the repetition-rate difference from 300 Hz to 80 kHz. • Free-running dual-comb time-of-flight ranging with micrometer precision is demonstrated, confirming high mutual coherence. We demonstrate a polarization-multiplexed dual-comb Yb:fiber laser with a dual-phase-biased nonlinear amplifying loop mirror, exploiting the orthogonal axes of a polarization-maintaining fiber. The two generated combs operate at a nominal repetition rate of ∼ 51.52 MHz and have essentially identical and overlapping optical spectra. By adjusting one of the mirrors in the dual-phase-bias module, the repetition rate difference can be flexibly tuned from 300 Hz to 80 kHz. The stability of the repetition rate difference and the noise properties of the dual-comb laser are characterized. We performed a proof-of-principle ranging experiment using the time-of-flight method, achieving μm-level precision in a fully free-running operation. Owing to the compact reflection-type design, the dual-phase-bias module is well suited for integration into a monolithic component with fiber pigtails attached, enabling a simple and compact solution for dual-comb fiber laser generation.