Implementation of the proposed reliability assurance strategy for an InGaAsp/InP, planar mesa, buried heterostructure laser operating at 1.3 µm for use in a submarine cable

We discuss the implementation of a strategy designed to provide laser-light-emitting reliability assurance for 1.3-μm InGaAsP/InP lasers of the planar mesa, buried heterostructure type for use in a submarine cable application. The testing regimes include initial characterization (cosmetic and light-current curve inspection), passive aging (elevated temperatures [85 to 175°C] without bias, with and without humidity [≤85-percent relative humidity]), overstress active aging (high temperatures [150°C], high currents [250 mAdc]), and long-term rate-monitoring active aging (elevated temperature [60°C] burn-in [3 mW/facet]). Overstress testing is designed to compel a timely (∼102-hour) identification of premature failures, due to modes of degradation other than the long-term ultimately controlling wear-out mode, and to stabilize transient modes. To identify premature failures of the wear-out type, survivors of overstressing are subjected to rate monitoring in which wear-out degradation rates, established in a reasonable time (∼103 hours), may be sorted. The principal results of the important overstress aging were the detection of an initially occurring saturable degradation mode, present to some extent in most lasers, and a regimen to force its rapid stabilization, so that it would not obscure determination of the activation energy of the wear-out mode. With a credibly determined value for the latter, it was deterministically inferred from rate-monitoring results that the light-emitting reliability of the screened lasers at ocean bottom temperatures (10°C) is more than adequate to meet the system design lifetime of 25 years.