Effect of the ridge geometry on the thermal properties of GaInAs quantum cascade laser

In this paper, the thermal behavior of GaInAs/AlInAs quantum cascade lasers is studied and compared with experimental reported data. The temperature distribution in the structures is obtained by solving the heat conduction equation using the Finite Element Method and a two-dimensional heat-flow model. In calculation, the anisotropy of the thermal conductivity due to the phonon scattering at the interfaces was considered. The thermal resistance was calculated and compared with experimental data reported by other authors, obtaining a very good agreement. A comparison of the heat dissipation in QCLs structures with the same active region, but having different waveguides: standard ridge, buried and double channel was performed. The influence of design parameters such as the depth and width of the ridge contact on the active region temperature is analyzed. The effect of the material used as heat sink was also evaluated.