Catastrophic Optical Bulk Damage in High-Power InGaAs-AlGaAs Strained Quantum Well Lasers

High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well lasers are critical components for terrestrial and space satellite communications systems. Thus, it is crucial to understand reliability, failure modes, and degradation mechanisms of these lasers for the high-reliability applications. However, a little has been reported on failure modes and degradation mechanisms of state-of-the-art SM and MM InGaAs-AlGaAs strained quantum well (QW) lasers. This study addresses the aforementioned issues by performing long-term life tests, failure mode analysis (FMA), and physics of failure (root causes) investigation. We performed long-term accelerated life tests on SM and MM InGaAs-AlGaAs strained QW lasers. Our life tests have accumulated over 25 000 test hours for SM lasers and over 35 000 test hours for MM lasers. FMA was performed on degraded lasers using electron-beam-induced current, electroluminescence, focused ion beam, and high-resolution TEM. All the SM failures showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or catastrophic optical bulk damage (COBD) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, we are the first group demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques for the physics of failure investigation including deep level transient spectroscopy, time-resolved electroluminescence, and time-resolved photoluminescence to investigate COBD processes in SM and MM lasers.