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High-power broad-area lasers are critical components for space satellite communications systems. Broad-area lasers with InGaAs-AlGaAs strained Quantum Well (QW) active regions are currently used in space satellite systems. These QW lasers have shown excellent power and efficiency characteristics, but these lasers are still susceptible to COD (catastrophic optical damage) leading to catastrophic and sudden degradation. Thus, their long-term reliability in space environments is a major concern. Furthermore, our group has shown that these lasers predominantly degrade by a new failure mode due to Catastrophic Optical Bulk Damage (COBD). The 3-D confinement of carriers in InAs-GaAs Quantum Dot (QD) active region has a potential to suppress nonradiative recombination of carriers at growth or radiation induced defect sites. This feature makes the QD lasers attractive for space applications. For the present study, we employed time-resolved analysis techniques including time-resolved electroluminescence (TR-EL) and time-resolved photoluminescence (TR-PL) techniques to investigate degradation in high-power broad-area lasers. We studied broad-area lasers with two different types of active regions – strained InGaAs-AlGaAs single QW layer and ten stacks of InAs-GaAs QD layers. TR-EL techniques were employed for time-resolved analysis of degradation processes in QW and QD lasers to study the sequence of critical events including the formation and propagation of dark line defects in ⪅110⪆, ⪅11̅0⪆, and ⪅100⪆ directions during accelerated life-tests. TR-PL techniques were employed to measure carrier lifetimes in QW laser wafer. Lastly, we report our understanding on degradation mechanisms in broad-area lasers with QW and QD active regions.
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