Evaluating the effects of nonlinear optical gain and thermal carrier escape on the performance of InGaAs/GaAs self-assembled quantum dot lasers

Abstract

The present paper reports the effects of nonlinear optical gain and thermal carrier escape on light-current characteristics in self-assembled quantum dot (QD) lasers based on a rate equation model. Comparison of the obtained simulated results with empirical findings showed that it is necessary to consider the effects of thermal carrier escape and nonlinear optical gain in order to evaluate dynamic and static characteristics of self-assembled QD lasers. Moreover, it was revealed that the describing terms of the thermal carrier escape from QDs is not enough in order to describe the effects of temperature on dynamics of carrier escape. Also, it was found that rate of (thermal) carriers stimulation depends directly on the inhomogeneous broadening (IHB). In other words, changes of IHB effects on the dynamics of thermal carrier changes. In addition, the results showed that optimized amount of homogenous broadening (HB) in which the maximum emission occurs in the central mode depended on both IHB and temperature. Comparing two conditions of linear and total optical gain illustrated that output power decreases if linear gain is replaced by total gain; also, lasing emissions broadens and number of lasing modes increases by increase in current. Investigating the effect of carrier’s relaxation lifetime on output power showed that increase of relaxation lifetime increases the threshold current and decreases the output power and slope efficiency. Furthermore, increase in relaxation lifetime caused decline in maximum output power and broadening of lasing spectrum.