Dissipative soliton with sidebands on spectrum in an all-fibre laser

We experimentally observed a dissipative soliton (DS) in an all-fiber laser with large-normal dispersion. The nonlinear polarization rotation (NPR) technique was used as the mode locker. The DS exhibited obvious sidebands on the spectrum, a feature that is distinctly different to that of the common DS previously reported. The spectral bandwidth was 57.43 nm, and the pulse duration was 2.20 ps. Remarkably, in the whole mode-locked pump regime, the DS remained in the single pulse state without multipulse shaping. Moreover, the pulse was compressed to similar to 140 fs by a negative dispersion device outside the cavity, and the pulse peak power reached 3.79 KW. We assumed that the spectral sidebands originated from the combined action of the nonlinear phase chirp and NPR-induced transmittance modulation, which may help to keep the mode-locked pulse working in the single pulse state. This work could help us gain a deeper insight into the DS formed in the normal dispersion regime.