The catastrophic degradation of laser diodeswith active zones comprising either single (SQW) or multiple quantum wells (MQW) has been analysed via finite elementmethods. This analysis is based on a physical model that explicitly considers the thermal and mechanical properties of the diode laser structure and the relevant size effects associated with the small thickness of the active layers of the device. The reduced thermal conductivities and the thermal barriers at the interfaces result in a significant local heating process which is accentuated as more quantum wells form the active part of the device. Therefore, in the design of high power devices, the SQW configuration would be more appropriate than the MQW alternative.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref VA293U13 and VA081U16 (003)Ministerio de Economía, Industria y Competitividad (ENE2014-56069-C4-4-R
