Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs-based diode lasers

COD diagram determined for a batch of broad‐area AlGaAs diode lasers. The time to COD within a single current pulse is plotted versus the actual average optical power in the moment when the COD takes place. Full circles stand for clearly identified COD events (right ordinate), whereas open circles (left ordinate) represent the pulse duration in experiments, where no COD has been detected. A borderline (gray) exists between two regions, i. e., parameter sets, of presence (orange) and absence of COD (blue). This borderline is somewhat blurred because of the randomness in filamentation of the laser nearfield and scatter in properties of the involved individual devices. Semiconductor lasers are the most efficient man‐made narrow‐band light sources and convert up to three‐quarters of electric energy into light. High‐power diode lasers are characterized by very high internal power densities in their small cavity, resulting in local heating and sometimes device degradation. Catastrophic optical damage (COD) of diode lasers is a relevant degradation mechanism and limit for reaching ultra‐high optical powers. An overview is given on research of the COD process in GaAs‐based diode lasers emitting in the 630–1100 nm range.