Analysis of low-frequency noise characteristics is used to investigate the behavior of gain-coupled buried-heterostructure lasers. Devices which exhibit threshold current degradation during electrical and thermal overstress, as well as stable devices, are examined. In addition to examining the magnitudes of the optical and electrical noise as functions of current and frequency, the correlation between the electrical and optical noise is examined. It is shown that unreliable lasers exhibited white electrical and optical noises with negative correlation between them at threshold while the reliable devices did not. While the root cause of these characteristic noise differences is as of yet unknown, the present results suggest the potential utility of noise measurements as a means of predicting laser reliability and the development of low-cost screening techniques. Q 2002 American Vacuum Society.