Collision and State Transition of Dissipative Solitons Induced by Gain Dynamics

Based on the experimental platform of an L-band normal-dispersion mode-locked fiber laser, we report the first observation, to the best of our knowledge, of the collision of dissipative solitons (DSs) and concomitant state transition with chaotic behavior by the dispersive Fourier transform technique (DFT). The gain depletion and recovery of Er
³⁺
in L-band cause the DSs that are close to each other to experience different gain spectra, thus giving them different central wavelengths and group velocities. As a result, collisions occur and lead to transitions between different pulsation and stable DS state. The experimental results provide new insights into the complex multi-soliton dynamics under unstable mode-locking conditions. It is confirmed that more than one soliton solution can coexist in a multi-pulse situation related with the gain dynamics. Our experimental results extend the exploration of multisoliton and soliton pulsation in laser state transition, and contribute to the study of soliton stability and laser dynamics.