Wavelength Convertible Flat/Tilt-Top Dissipative- Soliton-Resonance Pulses in an Anomalous Dispersion Fiber Laser

Dissipative soliton resonance (DSR) fiber lasers can generate high-energy optical pulses, which can be in two different time envelope modes: flat-top and tilt-top square pulses. However, there are few reports on the formation mechanisms of these two forms. Here, we investigated a figure-of-nine fiber laser with a large anomalous dispersion. By adjusting the polarization controller states and pump power of the resonant cavity, flat or tilt-top DSR square pulses and their harmonic mode-locking patterns were all obtained, and their formation mechanisms were theoretically analyzed. In addition, by adjusting the polarization states of the resonant cavity, the working wavelength of the DSR laser can be converted between the C-band and L-band. The research results can provide assistance for a deeper understanding of the dynamic characteristics of DSR fiber lasers.