Reliability and low-frequency noise measurements of InGaAsP MQW buried-heterostructure lasers

A laser diode reliability test based on the measurements of the low-frequency optical and electrical noise, and their correlation factor changes during short-time ageing is presented. The noise characteristics reveal obvious differences between the stable and unreliable lasers operated near the threshold region. An excessive Lorentzian type noise with negative correlation factor at the threshold could be one of criteria for identifying unreliable lasers. The behaviour of unreliable lasers during ageing could be explained by migration of point recombination centres at the interface of an active layer, and by the formation of defect clusters.