Effects of the carrier relaxation lifetime and inhomogeneous broadening on the modulation response of InGaAs/GaAs self-assembled quantum-dot lasers

Abstract

In this paper, a theoretical model is used to investigate the lasing characteristics of InGaAs/GaAs quantum-dot lasers. The rate equations for InGaAs/GaAs are numerically solved using the fourthorder Runge-Kutta method. Self-assembled quantum-dot lasers are studied considering the homogeneous and inhomogeneous broadening of the optical gain, as well as the nonlinear gain and thermal carrier escape from quantum dots. For different carrier relaxation times, the current-output power characteristics and light emissions of the quantum-dot laser have been calculated. The effect of the coverage factor is studied, and an optimized value is introduced for each carrier relaxation time. Moreover, the modulation responses for various inhomogeneous broadening and relaxation times are presented. Simulated results show that increasing the relaxation time decreases the modulation bandwidth. Furthermore, an increase in inhomogeneous broadening decreases the modulation bandwidth.