Polarization-Dependent Locking in SOA Harmonic Mode-Locked Fiber Laser

Polarization-dependent states of the output pulse train generated from an active harmonic mode-locked fiber laser by exploiting the birefringence of the fiber ring is reported for the first time. There exist two different fundamental frequencies for each polarization-mode lasing and hence the laser can be forced to mode-locking states of the two orthogonal polarization regimes by tuning or detuning the modulation frequency. Theoretical equations for predicting the tuning frequencies are described and good agreement with experimental results is obtained