Multiscale electrothermal simulation of quantum cascade lasers

Quantum cascade lasers (QCLs) are high-power, coherent light sources that emit at midinfrared and terahertz frequencies. The active core of these devices is a periodic multiple-quantum-well heterostructure where the electronic and lattice systems exist far from equilibrium and are strongly coupled. Heat generated in the active core (the part responsible for light emission) diffuses throughout the rest of the device. Coupled charge and heat transport in QCLs present a multiscale and multiphysics problem that governs device properties observed in experiment, such as the current-voltage characteristics, gain, and internal quantum efficiency. We present a strategy for simulating coupled heat and charge transport in QCLs, which occur on drastically different spatial scales, that employs a coupled ensemble Monte Carlo for electrons and phonons in a stage-level simulation of the active core and couples to a device-level heat diffusion simulation.