All-Polarization-Maintaining Mode-Locked Fiber Laser with Tunable Evolution of Dual-Wavelength Pulse States

Abstract

All-polarization-maintaining fiber (all-PMF) lasers can greatly improve the operational stability and integration of multi-pulse sources, serving as highly promising alternatives to conventional multi-cavity sources. In this work, we propose a simple intracavity modulation strategy to regulate dual-wavelength pulse states by adjusting the rotational splicing angle of polarization-maintaining single-mode fibers (PM-SMFs). This method enables precise modulation of intracavity polarization coupling and spectral response of the equivalent Lyot filter. With this scheme, we realize the continuous and controllable transition from asynchronous dual-comb pulses to synchronous bound solitons in an all-PMF fiber laser mode-locked by a carbon nanotube saturable absorber. When the splicing angle is fixed at 45°, the laser outputs stable asynchronous dual-comb pulses with a repetition frequency difference of 1.35 kHz. Furthermore, the dynamic evolution of synchronized bound solitons with phase differences from π to π/2 is also observed at a splicing angle of 30°. This work provides a feasible solution for flexible manipulation of dual-wavelength pulse nonlinear dynamics, and lays a foundation for the development of compact, high-stability multifunctional ultrafast fiber lasers and dual-comb sources.