Improved high-temperature operation of InGaAs/AlGaAs high-power quantum well lasers by short-period superlattice barriers

The electrooptic characteristics, like threshold current I_th and differential quantum efficiency η_d, of lnGaAs/AlGaAs quantum well lasers generally degrade with rising operating temperature. To ensure high output power and long lifetime, high power diode laser bars are actively cooled by microchannel heat sinks. If the strong temperature dependence of the electrooptic characteristics was reduced, the same output power could be reached using passive cooling. We have demonstrated a short-period superlattice (SSL) large optical cavity (LOC) SQW laser with a very high characteristic temperature T₀ above 300 K which is almost twice as much as for a standard LOC laser. We also showed that the main factor which deteriorates the differential quantum efficiency η_d, with temperature is the drop of the internal quantum efficiency η_t and not an increase of the internal loss as often supposed. The introduction of the SSL layer has increased the differential series resistance by a factor of about 1.5 which leads to a slight reduction in the maximum wallplug efficiency