Repetition rate difference, stability and polarization extinction ratio of single-cavity polarization-multiplexed fiber laser with weak birefringence

We investigated a stable single-cavity polarization-multiplexed ring fiber laser with weak birefringence. The feasibility of the weak intrinsic residual birefringence to induce polarization-multiplexed pulses with low repetition rate difference under dual/triple-comb modes is experimentally verified. The significant evolution of the relative stability and polarization extinction ratio, and its physical mechanism are revealed when adjusting the linear intracavity loss. These results provide further understanding of the influence of birefringence amount, loss, dispersion, and multiple pulse interaction on the polarization-multiplexed pulses. Meanwhile, the intriguing pulse characteristics such as low repetition rate difference, qualified relative stability and unique wavelength/polarization multiplexing are experimentally obtained, showing the high potential to promote the wide applicability and performance improvement of multiple-comb metrology such as dual/triple-comb frequency measurement.