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High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained QW lasers are critical components for space satellite systems. Both SM and MM QW lasers have shown excellent output power and efficiency characteristics, but these lasers are susceptible to COD. In addition, our group has shown that these lasers predominantly degrade by a new failure mode due to catastrophic optical bulk damage (COBD) leading to catastrophic and sudden degradation, which is a major concern for space applications. In recent years, InAs-GaAs quantum dot (QD) lasers have received much attention as an alternative to QW lasers for Si Photonics because 3-D confinement of carriers in QD lasers reduces the chance of nonradiative recombination of carriers at growth or radiation induced defect sites. This feature also makes the QD lasers attractive for space applications, but their failure modes and mechanisms are still unknown. For the present study, we investigated high-power broad-area lasers with strained InGaAs-AlGaAs QW and InAs-GaAs QD active regions. We performed short-term and long-term accelerated life-tests and failure mode analysis using various destructive and nondestructive techniques. We employed electroluminescence (EL) and time-resolved electroluminescence (TR-EL) techniques to study degradation processes in QW and QD window lasers. This configuration allows for observation of critical events including self-focusing of filaments, formation of dark spot and dark line defects (DLDs), and propagation of DLDs in real time during life-tests. We also employed focused ion beam (FIB) techniques to prepare TEM cross sections and plan-view TEM specimens of degraded QW and QD lasers for structural and defect analysis using a high-resolution TEM. Finally, we report our physics of failure investigation results on failure mechanisms in high-power broad-area lasers.
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