Sinusoidal Spectral Filtering-Based Soliton Dynamics in Mode-Locked Fiber Lasers

Sinusoidal spectral filtering (SSF) plays an essential role in dual- and multi-wavelength operations in mode-locked fiber lasers. However, the impact of SSF on the underlying soliton dynamics has not been systematically revealed so far. Herein, we investigate numerically the SSF-based soliton dynamics in mode-locked fiber lasers. SSF could facilitate the formation of dual-wavelength mode locking, and the generation of dual-comb solitons with slightly different group velocities. Pulse shaping based on SSF and gain filtering leads to the non-monotonic relationship between both solitons' group velocity difference and the cavity gain. In addition, dual-comb soliton mode locking exhibits threshold feature and multi-pulse instability to soliton annihilation and diverse soliton coexistences. Our investigations could shade new light on the SSF-based soliton dynamics and might bring new insights into the laser design and applications.