Facet Heating Mechanisms in High Power Semiconductor Lasers Investigated by Spatially Resolved Thermoreflectance

Thermal properties, degradation behaviour and optical and current contributions to facet heating of high power diode lasers emitting at 808 nm are analysed. The investigated devices with non-injected facets are designed to reduce carrier recombination at the facet surface. Spatially resolved thermoreflectance spectroscopy is used to measure temperature distribution maps over the laser facet. This study compares the facet temperature distributions for fresh (undamaged) and degraded laser. The measurements results indicate for the strong contribution of reabsorption of the laser emission to the overall facet heating for lasers with non-injected facets.