Polarization-Multiplexed All-Fiber Polarization-Maintaining Single-Cavity Dual-Comb Fiber Laser with RF-Referenced Repetition-Rate Stabilization

We demonstrate an all-fiber polarization-maintaining (PM) single-cavity dual-comb fiber laser based on intracavity polarization multiplexing. Two pulse trains share a common cavity section while two partially non-common branches provide independent gain, spectral filtering, and cavity-length control. The repetition rates are approximately 37.281 and 37.270 MHz, giving a repetition-rate difference of about 11 kHz. With radio-frequency (RF)-referenced repetition-rate stabilization, the 1 h standard deviations of frep1, frep2, and Δfrep, measured with a 1 s gate time, are 290, 178, and 342 μHz, respectively, corresponding to fluctuation-suppression factors of 6.3×105, 1.2×106, and 4.4×105 relative to free-running operation. Stable dual-comb operation is also obtained at discrete, fiber-length-customized working points near 4, 11, and 43 kHz. Autocorrelation measurements give pulse durations of 30.02 and 36.39 ps for the two outputs. A free-space ranging demonstration at Δfrep=4 kHz yields a precision of 96.3 μm at a 250 μs update time, which improves to 2.7 μm after averaging 400 points (100 ms). The proposed architecture combines all-fiber PM propagation, branch-level controllability, and RF-referenced repetition-rate stabilization in one single-cavity platform.