Passively mode-locking fiber lasers for generating high repetition frequency pulse based on MoWSe2 saturable absorbers

Transition metal dichalcogenides (TMDs) have increasingly attracted the interest of researchers due to their exceptional physical and chemical properties and broad application prospects. Currently, research on the application potential of the novel ternary TMD alloy MoWSe2 as a saturable absorber (SA) is not yet mature. This artical achieves mode-locking for the first time after implementing Q-switching in MoWSe2 SA. This study employed the liquid-phase exfoliation (LPE) method to fabricate a high-quality MoWSe2 SA with a modulation depth of 7.9 % and a saturation intensity of 14.7 MW/cm2. Stable conventional solitons (CS) and harmonic mode-locking (HML) of multiple orders were achieved. The highest order of HML reached the 86th order, with a maximum repetition frequency of 374.8 MHz. This represents the highest repetition frequency achieved to date in fiber lasers based on a MoWSe2 SA. The results show that MoWSe2 SA exhibits excellent nonlinear optical modulation performance, which lays the foundation for its role in advancing academic exploration and innovation in engineering practice in the field of ultrafast photonics.