Tunable high energy pulses with a low repetition rate from a passively mode-locked Yb-doped fiber laser

A tunable, low-repetition rate, all-normal-dispersion Yb-doped fiber laser (YDFL) that is passively mode locked based on phase shift long period fiber grating (PS-LPFG) is demonstrate and proposed. The mode-locking mechanism of the laser is based on nonlinear polarization evolution (NPE). Using a PS-LPFG as the spectral filters in the laser cavity, the mode-locked output wavelength can be tuned continuously and smoothly over a spectral range of 10nm, it is the maximum tunable range of the giant chirped pulse with all-fiber format bandpass filter in YDFL as we known.