Waveguide engineering for low dispersion mid-infrared quantum cascade lasers frequency combs

Quantum Cascade Lasers (QCLs) have become one of the most used light sources in the Mid-IR. It has been demonstrated that QCLs can operate as frequency combs (FCs) [1] and that the performance of QCL FCs can be significantly improved by compensating for their waveguide dispersion using dielectric coating based Gires-Tournois interferometers [2]. However, the latter are incompatible with high optical output power since due to the optical absorption of the materials they overheat and burn. In this work we investigate how the properties of mid-IR QCL FCs can be improved by tailoring their waveguide dispersion.