Soliton rains with isolated solitons induced by acoustic waves in a nonlinear multimodal interference-based fiber laser

Abstract We experimentally and theoretically demonstrate soliton rains with isolated solitons and soliton bunches in a passively mode-locked fiber laser, using a mode-locker based on a nonlinear multimodal interference technique. The isolated solitons are captured at the moments of integer multiples of 21 ns and 33 ns, which correspond to the acoustic modes in TR 2m and R 0m branches. The theory of nonlinear fiber optics is used to characterize the mechanism of capturing isolated solitons. The modal delay induced by the multimode fiber gives a revealing insight into the loss of capacity to capture and transition from soliton rains to bunches. Our study introduces a new way to precisely control the behaviors of multi-solitons and provides a potential tool for understanding complex nonlinear dynamics.