Analysis of GaN based high-power diode lasers after singular degradation events

Damage patterns caused by the Catastrophic Optical Damage (COD) are analyzed in GaN-based high-power diode lasers. In contrast to standard failure analysis, the devices are intentionally degraded under well-defined conditions. We find that defect growth during COD is fed by the optical mode, that is, laser energy. This process involves melting and even vaporization of quantum-well and waveguide materials. Average defect propagation velocities along the laser axis of 110 m s−1are observed. COD results in material loss including the formation of an empty channel. This is well consistent with material loss due to ejections of hot material out of the front facet of the device. The laser structure in the immediate vicinity of the empty channel seems to be absolutely undisturbed and no transition regions or remaining material are observed. These results are compared with earlier findings from comparable experiments obtained with GaAs-based devices.