Self-consistent thermal simulation of GaAs/Al0.45Ga0.55As quantum cascade lasers

Abstract

This paper presents a self-consistent thermal model for quantum cascade lasers (QCLs) that takes into account the nonuniform heat generation distribution in the active region as well as the temperature dependences of the heat generation rate and thermal conductivity. The model extracts the heat generation rate from the electron-optical phonon scattering recorded during the ensemble Monte Carlo (EMC) simulation of electron transport in a single QCL stage at different temperatures. The extracted heat generation rate, in conjunction with temperature-dependent thermal conductivities, enables us to solve the nonlinear heat diffusion equation in a self-consistent manner. The model is used to investigate the cross-plane temperature distribution throughout a 9.4 μm infrared GaAs-based QCL. The nonlinear effects stemming from the temperature dependence of thermal conductivity and the heat generation rate are studied. Finally, the accuracy of using the equivalent uniform heat source with the total power obtained from experiments to model the thermal performance of QCLs is evaluated and discussed.