Analysis and Comparative Study between Dynamical Regimes of Passive and Hybrid Mode-Locked Quantum Dot Lasers

In this article, the operational regimes and behavior of passively mode-locked quantum dot (QD) lasers have been investigated based on analyzing delay-differential rate equations and exploiting short and long saturable absorber criteria. Then, these criteria have been used for hybrid mode-locked QD lasers for the first time and it has been shown that elimination of unwanted Q-switching, Qs, Q-switching mode-locked, QS-ML regimes, decrease of the threshold current for all operation regimes, and enhancement of the extinction ratio for generated pulses can be obtained in short-absorber hybrid structure compared with passively mode-locked QD lasers. Also, by analyzing the pulse and harmonic pulse frequency generation mechanisms, proper approaches for generation of higher-frequency harmonic pulses especially third harmonic generation and increase of required dynamical regimes’ range have been discussed.