Evolution of invisible soliton pulsation in a mode-locked fiber laser (Invited)

The real-time observation of the tripling periodic invisible soliton pulsation in a mode-locked fiber laser with the dispersive Fourier transformation technique was reported. Since the three modulation frequencies were commensurate, the soliton pulsating behavior exhibited good periodicity rather than quasi-periodicity. After analyzing the soliton pulsating evolution, it was identified that the soliton modulation instability caused the generation of parametric sidebands and pulsating instability. The parametric process between soliton and dispersive waves induced the energy exchange between them. Consequently, there was no obvious total soliton energy variation during the evolution of soliton pulsation. As a result, the invisible soliton pulsation could not be visualized directly by the pulse train. In addition, by merely increasing the pump power with other cavity parameters unchanged, the entire route from the invisible soliton pulsation generation to stable dual-soliton pulses was systematically analyzed. Compared with the conventional visible soliton pulsation, the modulation periodicities of the invisible soliton pulsation showed weaker variations along with the pump power elevation. Our work not only contributed to understand the soliton pulsating dynamics in depth but also provided great assist to the optimization of laser performance.