Polarization Dynamics of Mode-Locked Fiber Laser

By using a new vector model of Erbium-doped fiber laser with a mode-locking mechanism based on a nonlinear polarization rotation, we demonstrate, for the first time, a transition from a stable mode-locking with a locked state of polarization (SOP) to an unstable mode-locking with periodically and chaotically evolved SOP. The chaotically evolving SOP corresponds to the intermittent behavior of the pulse energy (alteration between the chaotic and laminar phase regimes) similar to the experimentally observed.