Collision and dissociation of soliton molecules triggered by gain perturbation in passively mode-locked fiber laser.

Soliton molecule has the properties that similar to those of matter molecule, which brings great research value. The rich dynamics of soliton molecules depend on the complex interactions between pulses. As one of the important factors, gain dynamics has multi-dimensional effects on the interactions of soliton molecules. We here study the interaction process of soliton molecules under gain perturbation, and find the oscillation and collision behaviors of pulses within soliton molecules induced by gain perturbation, as well as the pulses recombination through interactions between soliton molecules. We believe that the energy change in the cavity and the energy transfer based on the continuous wave component play an important role in the evolution process of the dissociation of soliton molecules into three-pulses bunch and single pulse. These findings reveal the effects of gain on the motion of soliton molecules and provide a basis for exploring the control dynamics of soliton molecules.