ACCELERATION OF THE GRADUAL DEGRADATION IN (GAAL)AS DOUBLE-HETEROSTRUCTURE LASERS AS AN EXPONENT OF THE VALUE OF THE DRIVING CURRENT

Double-heterostructure (GaAl)As lasers are tested at various temperatures and driving conditions, including spontaneous mode operation. Results show that the rate of degradation is primarily determined by driving current rather than optical output when aging at optical outputs of 10 mW/facet or less and heat-sink temperatures of 50-100 °C. A new composite Arrhenius relation including a current-dependent factor is empirically derived, and excellent agreement is found between calculated and experimental results, especially in regard to the effects of current on the rate of gradual degradation. The thermal activation energy derived by the above relation is estimated to be 0.8±0.1 eV, and laser lifetime at an optical output of 5 mW/facet and heat-sink temperature of 25 °C is expected to exceed 3.4×10 5 h. The role of current in inducing gradual degradation is also discussed.