PHOTOLUMINESCENCE MEASUREMENT OF THE FACET TEMPERATURE OF 1 W GAIN-GUIDED ALGAAS GAAS LASER-DIODES/

The output facet temperature of high-power AlGaAs/GaAs single quantum well (SQW) laser diodes was measured during operation. The front outpu t facets were passivated with Al2O3 coatings. The spectral shift of ph otoluminescence from the cladding layers was used to determine the tem perature rise at the front facet with increasing output power. The spa tial resolution of the technique allowed to look at each cladding laye r individually and to study the correlation between the near-field pat tern and the temperature profile along the active layer. The local tem perature on the facet at 1 W total optical power (corresponding to an average linear power density of 10 mW/mu m) was found to vary between 25 and 45 K above the average active layer temperature and to exceed t he heat-sink temperature by up to 70 K. This represents a significant reduction of facet temperature in comparison to earlier reports and ca n be attributed to high-quality passivation coatings. (C) 1996 America n Institute of Physics.