Soliton molecules in a fiber laser based on optic evanescent field interaction with WS2

Abstract

Passively mode-locked fiber laser serves as an ideal playground for exploring the dynamics of dissipative solitons. Recently, two-dimensional materials have attracted growing interests for their excellent optical properties in the research field of ultrafast optics. Here, we report an observation of soliton molecules in a passively mode-locked fiber laser based on optic evanescent field interaction with tungsten disulfide (WS2), which contributes to the study of multi-soliton complexes. Particularly, the WS2 saturable absorber (SA) is fabricated by optically depositing the few-layer WS2 nanosheets onto microfiber. In the experiment, stable mode-locking operations are realized, which manifest the effective performance of the WS2 SA. Harmonic mode-locking phenomena are also observed, and these separate solitons facilitate the generation of multi-soliton complexes. Furthermore, due to soliton–soliton interaction, wandering particle-like solitons can be bound together to produce soliton molecules and bunch of soliton molecules. These results enrich both the exploration of multi-soliton complexes and potential industrial applications.