Thermal runaway and optical efficiency in InAs/GaAs quantum dot lasers

In contrast to quantum well lasers, we show thermal runaway effects are prominent for quantum dot (QD) lasers emitting at 1300 nm. In addition to the surface states at the cleaved facet and the effect of strain relaxation, which can couple confined states with surface states, the exposed relaxed QDs at the cleaved facet can themselves contribute to extra nonradiative surface recombination, aggravating the facet heating problem. Notable improvement in optical efficiency after the formation of nonabsorbing mirrors by a laser annealing technique highlights the significance of the thermal runaway problem for 1300 nm QD lasers, and demonstrates an effective postfabrication solution. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3245305]