Gain-switched pulses from quantum-dot laser excited state

Abstract

In this paper, the investigation of gain-switching characteristics of an InAs/InP Quantum dot laser is performed for direct and cascade relaxation models, theoretically. The model is based on single mode rate equations, which are solved by the Runge-Kutta method. Moreover, the effect of external optical beam irradiation to the excited state are investigated for both relaxation models. Our results showed that for the first time, under the optical Gaussian pulse beam it is possible to generate short pulses with a width of around 30 ps with a high peak power for the direct and cascade relaxation models. It was also found that in the absence of external optical beam irradiation, width and peak power of output pulses for cascade relaxation model are slightly smaller than that of direct relaxation model whereas in the presence of optical beam, they are approximately the same for both models. Obtained results have great importance for the fields where short optical pulse is an important demand such as long-distance optical transmission and medical biotechnology.