Degradation Processes in High-Power Broad-Area Lasers with Strained InGaAs-AlGaAs QW and InAs-GaAs QD Active Regions

High-power broad-area InGaAs-AlGaAs strained quantum well (QW) lasers are indispensable components for space satellite communications systems. However, their degradation mode (catastrophic and sudden degradation) due to catastrophic optical damage is a major concern for space applications. Furthermore, these lasers predominantly degrade by a new failure mode due to catastrophic optical bulk damage (COBD). Also, InAs-GaAs quantum dot (QD) lasers have recently received much attention as an alternative to QW lasers especially for space applications, but their degradation mechanism is not well understood. For the present study, we investigated high-power broad-area lasers with two different active regions: 9xx nm strained InGaAs-AlGaAs QW and similar to 1 mu m InAs-GaAs QD active regions. Both lasers had a window formed in backside n-metals. We performed accelerated life-tests, failure mode analyses, and physics of failure investigations using destructive and non-destructive techniques. First, we employed electroluminescence (EL) and time-resolved electroluminescence (TR-EL) techniques to study precursor signatures of failures including the formation of a hot spot through self-focusing of filaments and thermal lensing as well as the formation and propagation of dark line defects (DLDs) in degraded lasers during aging. Second, we employed high-resolution TEM techniques to study extended defects. Finally, we report our understanding on degradation processes in high-power broad-area QW and QD lasers.