Transient surface modifications during singular heating events at diode laser facets

Surface morphology changes and transient reflectance changes at diode laser facets are monitored during the catastrophic optical damage (COD) process in a single pulse operation. Time-resolved micro-reflectance spectroscopy with a streak-camera (time resolution ~20 ns) allows us to observe the creation sequence of up to four distinct degradation seed points at a device facet within <300 ns. The shape of the COD seeds is created within <30–40 ns. Creation of non-planar facet areas by local melting represents the main mechanism behind the observed reflectivity changes. Subsequently the surface temperature decreases within the pulse which caused the COD.