Defect evolution during catastrophic optical damage of diode lasers

Abstract

We present an analysis of the catastrophic optical damage effect that is artificially provoked in 808 nm emitting broad area diode lasers by single current pulses. The kinetics of the sudden degradation process, monitored with a nanosecond temporal resolution, is linked to the damage pattern observed. This involves <I>in situ</I> tracing of emission power and hot-spot motion within the cavity as well as the verification of the resulting defects by defect spectroscopy and cathodoluminescence mapping. A complementary model is presented which explains the shape of the observed defect pattern. The combination of unidirectional energy transfer to defects by laser light within the laser cavity, spatially isotropic defect growth, and the presence of shadowing effects explain the complex damage pattern observed in the gain material, including effects of defect branching. The study is made with standard industrial devices making the findings directly applicable for device testing and performance improvements.