Reliability and low-frequency noise of InGaAsP MQW DFB lasers

Low-frequency noise characteristics and their changes during short-time ageing of InGaAsP multiquantum-well distributed-feedback laser diodes were measured with the aim of investigating the reliability of devices. The noise characteristics reveal obvious differences between the stable and degrading lasers operated near the threshold region - an excessive Lorentzian type noise with negative correlation factor was observed at the threshold of degrading devices. The behaviour of the degrading 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.