Asymmetric spectral pulsation in Er-doped mode-locked fiber lasers

Pulsation, as a state between order and chaos, has been extensively studied in theory and experiment, but the rich nonlinear dynamics behind it have not yet been fully revealed. In this work, we have experimentally revealed three spectrally asymmetric pulsation phenomena switched only by tuning the two polarization controllers: spectrally splitting recombination pulsation of solitons, pulsation phase shifting of the peaks of bound-state soliton spectra, and asynchronous pulsation of two pulsating coexisting soliton pairs. Theoretically, we analyzed these phenomena based on coupled Ginzburg-Landau equations. These findings provide perspectives to reveal the complex Hopf bifurcation phenomena in dissipative systems and bring valuable insights into nonlinear science and its applications.