Gain recovery dynamics and limitations in quantum dot amplifiers

Summary form only given. While ultra-low threshold current densities have been achieved in quantum dot (QD) lasers, the predicted potential for high-speed modulation has not yet been realized despite the high differential gain. Furthermore, recent single pulse experiments demonstrated very fast gain recovery in a quantum dot amplifier, and it is thus not yet clear what the limiting processes for the device response are. We present the results of a comprehensive theoretical model, which agrees well with the experimental results, and indicates the importance of slow recovery of higher energy levels. The model used is of the rate-equation type with three energy levels: ground state (GS) and excited state (ES) dot levels and a wetting layer.