Space-grade reliability of 808nm QCW laser diode arrays (LDAs) delivering over 20 billion shots

Space missions are probably the most demanding environment for laser diodes. A comprehensive study on the reliability of commercially available laser diodes arrays (LDA), with the objective of bar stacks for ESA's BepiColombo Laser Altimeter mission to the planet Mercury was performed. We report the best results of lifetime tests performed on SCD 808 nm QCW stacks at different levels of current load in a unique combination with operational temperature cycles in the range of -10°C to 60 °C. Based on a field-proven design that includes Al-free wafer material and a robust packaging solution, these arrays exhibit long operational lifetime of up to 20 billion pulses monitored in the course of several years. Zero failures and stable performance of these QCW arrays were demonstrated in severe environmental conditions reflecting both, military and space applications. In order to achieve maximum device efficiency at different operational conditions of the base temperature and current, an optimum combination of the wafer structure and bar design is required. We demonstrate different types of QCW stacks delivering peak power of up to 1 kW with a usable range of 50-55% wall plug efficiency at base temperatures up to 60 °C.