Spectral-filtering-induced phase transition in passively mode-locked fiber lasers

We investigate the effect of a tunable spectral filter on the dynamics of a passively mode-locked fiber laser in the anomalous dispersion regime. The results show that noise-like pulse emission evolves toward bound-state regime as the filter bandwidth is reduced. Thanks to the Shannon entropy applied to dispersive Fourier transform signals, it is demonstrated that the system undergoes a phase transition.