Quantum Dot Passively Mode-Locked Lasers: Relation Between Intracavity Pulse Evolution and Mode Locking Performances

We present a systematic investigation of the passively mode-locked (ML) quantum dot lasers using a Finite Difference Traveling Wave model. Device structural parameters, such as the saturable absorber (SA) length, the total cavity length, and the facets reflectivity, have been varied. The obtained results indicate a strict relation between the ML performances and the intracavity evolution of the forward/backward travelling ML pulse. We demonstrate that shorter pulses can be achieved in devices with higher intra-SA pulse energy thanks to the enhanced absorption saturation.