Efficient use of all ports of a 3 × 3 coupler in a nonlinear amplifying loop mirror-based fiber laser

We present an all-polarization-maintaining mode-locked fiber laser based on a nonlinear amplifying loop mirror utilizing a 3 × 3 coupler. A pump laser diode placed outside the cavity pumps both the oscillator and fiber amplifier. This laser configuration effectively utilizes all ports of the coupler, making the laser compact and low-cost, and has great potential as a seed laser for ultrashort pulse lasers.