Purified Dissipative Solitons With a Rectangle Spectrum From a Hybrid Mode-Locked Fiber Laser

We demonstrate a hybrid mode-locking erbium-doped fiber laser, which combines saturable absorption and nonlinear polarization evolution. The laser is operated in the large normal dispersion regime, offering rectangle spectrum and purified femtosecond pulses with a repetition rate of 3.05 MHz and an average output power of 50.31 mW. The single-pulse energy is 16.5 nJ and the pulse peak power is 26.1 kW, providing a robust ultrafast fiber laser well suited for frequency comb generations and high-power applications.