Dual-bandpass filter for self-starting mode-locking in All-PM NALM-based fiber laser

We report superiorities of a NALM-based all-PM fiber laser incorporating dual-bandpass filter instead of ordinal single narrow bandpass filter. The fiber laser starts mode-locking quickly with relatively low pump powers. Shorter wavelength bandpass window component of dual-BPF is used for inducing Q-switched mode-locking and enlarging amplitude noise. Longer wavelength bandpass window component is used for keeping CW mode-locking. Once the laser starts modelocking at longer wavelength window, spectrum components in shorter wavelength window are negligible. The laser produces various of ultra-fast pulses by adjusting longer wavelength window property.