Mode-locking of fiber lasers induced by residual polarization dependent loss of cavity components

摘要

We found experimentally that under strong pumping, mode locking could self-start in a fiber laser even without inserting a polarizer or a mode locker in the cavity. It was identified that the mode locking was caused by the large residual polarization dependent loss (PDL) of a cavity component. We have experimentally determined the strength of PDL in our fiber lasers. Our results show that in order to exclude the nonlinear polarization rotation (NPR) mode locking effect in a fiber laser one has to carefully select the intracavity components.