Polarization-duplexing of a ytterbium-doped fiber mode-locked laser with an intracavity birefringent crystal

Polarization-duplexing of a ytterbium-doped fiber mode-locked laser in all-normal-dispersion with an intracavity birefringent crystal is demonstrated. The laser outputs two asynchronous pulse trains with slightly different repetition rates, orthogonally crossed polarization, and colinear beams. The optical spectra are highly overlapped. A tuning of the repetition rate difference ranging from 3.7 to 8.6 kHz is realized by adjusting the birefringence in fiber. This laser offers a platform for exploring the compact fiber dual-comb lasers with tunable repetition rate differences.