From Two- to Three-Dimensional Model of Heat Flow in Edge-Emitting Laser: Theory, Experiment and Numerical Tools

Mathematical modeling of thermal behavior of edge-emitting lasers requires the usage of sophisticated time-consuming numerical methods like FEM (Finite Element Method) or very complicated 3D analytical approaches. In this work, we present an approach, which is based on a relatively simple 2D analytical solution of heat conduction equation. Our method enables extremely fast calculation of two crucial physical quantities; namely, junction and mirror temperature. As an example subject of research, we chose self-made p-side-down mounted InGaAs/GaAs/AlGaAs laser. Purpose-designed axial heat source function was introduced to take into account various mirror heating mechanisms, namely, surface recombination, reabsorption of radiation, Joule, and bulk heating. Our theoretical investigations were accompanied by experiments. We used micro-Raman spectroscopy for measuring the temperature of the laser front facet. We show excellent convergence of calculated and experimental results. In addition, we present links to freely available self-written Matlab functions, and we give some hints on how to use them for thermal analysis of laser bars or quantum cascade lasers.