Reliability of vertical-cavity lasers at Hewlett Packard

Vertical-Cavity Surface-Emitting Lasers (VCSELs) have rapidly been adopted for use in data communications modules due largely to the improvement in reliability over that of competing compact disc (CD) lasers. While very long mean lifetimes for VCSELs have been published elsewhere (>5x10(6) h MTTF at 40C)[1,2], telecommunications switching applications require further reduction in the early failure rate to meet targets of <0.5% failures over 25 years at 50-70C. Therefore, an extensive reliability program is needed to measure both the wear-out lifetime and the random failure rate of the devices. The results of accelerated life tests will be presented, and we will discuss the methodology used to estimate the failure rate. Models of current and thermal acceleration will be presented. Degradation mechanisms observed in HP lasers will be briefly discussed. We also present preliminary results from HP oxide-aperture VCSELs.