Impact of carrier heating on performance of quantum-dot semiconductor lasers: Theoretical study and circuit-level modeling

In this paper, we present a circuit-level model for quantum-dot (QD) semiconductor lasers from which the charge-carrier densities and temperature dynamics of carriers in the active region can be determined during device operation. The model is developed from the multi-population rate equations of QD lasers to include the dynamical evolution of the electron-hole pairs, and two-level energy balance equations to describe the electron and hole temperature dynamics in the device active region. The main feature of the model is that the electron and hole scattering processes between the reservoir and QD states are no constant times, but they are incorporated into the laser dynamical equations as nonlinear functions of carrier temperature and the reservoir charge-carrier densities. Using the presented model, we investigated the influence of carrier heating on static and dynamic properties of 1.55 mu m QD semiconductor lasers. As a main result, we found that the electrons in the active region have a higher temperature as compared to their hole counterparts, which can be attributed to the faster dynamical evolution of the electrons combined with the higher energy spacing between the reservoir and QD levels in the conduction band. The results are in agreement with theoretical and experimental data reported earlier.