Theoretical investigation of hybrid mode-locking in two-section semiconductor quantum dot lasers
WIAS , Germany
In the present work theoretical investigations of hybrid mode-locking in semiconductor quantum dot lasers were carried out using a mode-locking model based on a set of 3 delay-differential equations. The reverse bias modulation was described by a periodic variation of the carrier relaxation rate in the absorber section. Dependence of the locking range on the modulation amplitude and modulation shape has been studied numerically and analytically using asymptotic analysis. It has been shown that in the case of pulsed modulation shape locking range is asymmetric with respect to the frequency of passively mode-locked laser. This asymmetry is related to the dependence of the pulse repetition frequency on the modulation amplitude. Finally it has been demonstrated that the hybrid mode-locking regime can be achieved in the case when the modulation frequency is approximately twice higher or lower than the pulse repetition rate of the free running passively mode-locked laser.