Single and composite soliton rain patterns in a spatiotemporal mode-locked fiber laser

Abstract

We report the first observation of both single and composite soliton rain patterns in a spatiotemporal mode-locked (STML) fiber laser based on a nonlinear amplifying loop mirror. At high pump powers, our experiments reveal forward- and backward-drifting soliton release, accompanied by dynamic variations in the real-time beam profiles, as well as static soliton release with a stable beam profile. Notably, in the presence of multiple continuous waves coexisting with mode-locked solitons, distinct composite soliton rain patterns are achieved. These include the coexistences of soliton release with different conventional soliton rains or cyclic soliton rain. The results contribute not only to a deeper understanding of soliton rain patterns but also to the exploration of more complex dynamics in STML fiber lasers.