Thermal relaxation time and heat distribution in pulsed InGaAs quantum dot lasers

Using a charge coupled device-based thermoreflectance technique, we achieve a high-resolution (∼700nm) cross-sectional temperature profile of a semiconductor laser. This two-dimensional profile allows us to identify separate heat sources due to contact heating and nonradiative recombination in the active region. By adapting the technique to pulsed operation and varying the laser’s duty cycle, we measure the thermal relaxation time constant. We also quantitatively determine the heat transfer from device-internal heat sources and demonstrate both the large effect of lateral heat spreading and the distinction between a laser’s top surface temperature and its active region temperature.