An all polarization-maintaining fiber laser mode locked by nonlinear amplifying loop mirror with different biases

We report on an erbium-doped, mode-locked fiber laser incorporated with various phase-biased nonlinear amplifying loop mirrors. Our cavity employs all polarization-maintaining fibers so that the laser is environmentally stable and insensitive to thermal and mechanical perturbations. The laser with a π / 2 phase bias directly delivers 1.20 ps pulses at a repetition rate of 88.2 MHz. The output power is 37.0 mW and the single-pulse energy is ∼0.42 nJ, when the pump power is 450 mW. Since the phase bias plays an important role in enhancing self-starting properties, we mainly investigate the self-starting threshold and the phase noise of the fiber oscillator using three diverse phase biases. It is found that compared with λ / 6 and λ / 10 waveplates, the laser employing a λ / 8 waveplate has a lower self-starting threshold and higher phase noise.