Study of substrate modes in a (Al,In)GaN/SiC semiconductor laser using finite element approach

Penetration of the waveguide mode into the substrate has some effects in Nitride-based semiconductor lasers grown on Silicon Carbide while it is usually not a problem in Arsenide-based devices. We observe oscillations in the red part of the measured gain spectrum of an (Al,In)GaN semiconductor lasers. These have been attributed to the presence of a standing wave in the substrate. We use a finite element approach to solve the Helmholtz equation and a complex notation for the dielectric function. Our intention is to estimate the effects of localized optical loss on the waveguide mode. In order to analyze measured oscillation in the Hakki-Paoli experiment we need to take into account optical loss in the P-doped region and in the substrate.