Simulation and analysis of quantum cascade lasers

In quantum cascade lasers (QCLs), both the spectral gain characteristics and the nonlinear optical properties can be custom-tailored through quantum engineering. This enables mid-infrared and terahertz generation, and applications such as frequency combs. For the further development of QCL sources, suitable modeling approaches are required. Here we review various methods, ranging from semiclassical to quantum transport techniques. A focus will be on the adequate implementation of carrier-light interaction based on multi-domain simulation approaches to describe the actual lasing process and nonlinear optical effects. We demonstrate that by combining different models, we can exploit their corresponding strengths to significantly improve the performance of the simulation tool.