Time-domain dynamics of dispersive waves and Kelly sideband modulation in an anomalous dispersion dissipative soliton fiber

This study explores the generation and time-domain dynamics of dispersive waves (DWs) in a mode-locked dissipative soliton fiber laser operating in the net anomalous dispersion regime. By incorporating a narrow bandpass filter with large anomalous dispersion into the cavity, we achieved the generation of strong, broad DW pulses directly observable in the time domain. We demonstrate that by tuning the filter's center wavelength, the intensity asymmetry of Kelly sidebands can be effectively controlled, revealing the dominant role of gain in this asymmetry. Crucially, we report the first time-domain observation of dispersive wave modulation: increasing pump power induces Kelly sideband instability, manifested as spectral sub-sidebands and periodic intensity modulation on the DWs. Furthermore, we observed that continued pump power increase leads to the formation of new solitons from these modulated and unstable DW pulses, directly demonstrating the critical role of DWs in soliton evolution. These findings provide a deeper understanding of the complex interplay between dispersive waves and solitons in dissipative mode-locked fiber lasers, offering new avenues for controlling ultrafast pulse generation in these systems.