Synchronous-asynchronous laser mode-locking transition

Abstract

Synchronous-asynchronous mode-locking transition in a hybrid active and passive mode-locked laser is investigated theoretically. Three distinct mode-locking states are found and their transition diagram under varying detuning frequency and modulation strength is determined. By examining the steady-state lasing gain as a function of the detuning modulation frequency, we also clarify why the laser will become unstable near the transition points and why the nonlinear saturable absorption effect is crucial for the stable asynchronous mode-locking operation.