Dielectric Highly Reflective Mirror Coatings for 4–5 μm Quantum Cascade Lasers

Dielectric mirrors for mid-IR quantum cascade lasers are calculated. Optimal dielectric materials are selected to minimize the absorption of laser radiation. Samples of quantum cascade lasers emitting in the spectral range of 4–5 μm and having various dielectric highly reflective mirror coatings are manufactured and their characteristics are studied. It is shown that the deposition of a highly reflective Si–Si 3 N 4 coating on the back face of the laser cavity leads to an increase in the output optical power of the lasers by 71% compared to control samples without coatings. The use of a Si–SiO 2 coating makes it possible to increase the output power of the lasers by 88%.