Dissipative solitons in a compact Er-doped all-fiber figure-of-9 laser

We designed and demonstrated a compact all-fiber dissipative soliton (DS) fiber laser. The proposed Erbium doped fiber laser is mode-locked by nonlinear amplified loop mirror (NALM), which has a typical figure-of-9 structure and operates in normal net-cavity dispersion regime. The NALM-based fiber laser is constructed by only three polarization maintaining fiber components, which can generate long-term stable, self-started pulses with 0.29 nJ pulse energy and 354 fs pulse width under 55.6 MHz repetition rate. It is proved both numerically and experimentally that the essential dissipative mechanism for the DS generation is provided by spectral filtering effect of the NALM loop. Our results clearly show that the DS's spectral bandwidth can be modulated by changing length of the fiber in the NALM loop.