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 (∼10
²
-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 (∼10
³
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.