Temperature transients and thermal properties of GaAs/AlGaAs quantum-cascade lasers

The use of a gated interband photoluminescence technique has allowed the study of the temperature transients in the active volume of a quantum-cascade laser during pulsed operation. The active region was found to rise by ∼40 K during a 150 ns current pulse, returning to the heat-sink temperature in ∼500 ns. The measured temperature transients were fitted, using a one-dimensional heat diffusion model, giving a value of kAR=1.36±0.2 W cm−1 K−1 for the active region thermal conductivity, at 30 K. This is approximately ten times lower than literature values for bulk AlGaAs alloys of equivalent composition and has significant implications on the prospects for high-power continuous-wave device operation.