Microscopic degradation and failure processes in high-power diode lasers

Abstract

In this work we analyse the microscopic issues of the catastrophic optical damage (COD) of high power laser diodes. The COD is studied in terms of local heating of the active zone of the laser, which becomes an internal heat source fed by the absorption of the laser radiation generated in the cold cavity. The root causes of the formation of the hot spot in the QW are discussed, distinguishing between the COD induced by step tests and the long term COD. The role of the physical properties, optical absorption, thermal conductivity, mechanical strength and refractive index are considered in relation to the occurrence of COD. Also a comment about the reasons for the higher strength of the strained QWs is included. The analysis of the process is based in the thermomechanical modeling developed in the last years.