Raman study of the time evolution of the facet temperature of coated AlGaAs single-quantum-well lasers

Facet temperature and output power of coated AlGaAs single-quantum-well lasers were examined as a function of operating time. In contrast to previous results on uncoated lasers, which show a linear rise of facet temperature with time, these measurements on coated lasers show an initial rapid rise and then a substantial slowing of the temperature rise rate. Qualitatively similar behavior is observed in both the temperature rise and power degradation rates. Facet temperature measurements as a function of drive current at time zero show no observable discontinuity at threshold; however, formation of a kink at threshold is observed soon after stressing the lasers at constant current, suggesting a large role of photon heating in the facet degradation process.