27nJ, 114fs Pulses From an Environmentally Stable All-Normal All-PM Yb-Doped Fiber Laser Mode-Locked With a Nonlinear Amplifying Loop Mirror

We report on a self-starting mode-locked all-polarization-maintaining fiber laser using a nonlinear amplifying loop mirror. It delivers a 7.81 MHz train of pulses with an average power of 213 mW, corresponding to pulse energy higher than 27 nJ. The output chirped pulses can be recompressed down to ∼114fs with a grating pair compressor. The nonlinear phase shifts accumulated in the long fiber cavity can be used to compensate for the mismatched third order dispersion and increase the compressed pulse quality. The laser shows excellent stability and environmental robustness during the test.