Evidence for reduced thermal conductivity in quantum dot active region from chirp characteristics in InGaAs/GaAs quantum dot lasers

This study presents evidence for reduced thermal conductivity in quantum dot (QD) active region from chirp characteristics in InGaAs/GaAs quantum dot lasers. This study shows measurements of the wavelength of one of the F-P modes of the QD laser as a function of pulse width both above and below threshold. Measurements reveal that the displayed behavior is potentially due to the lowered thermal conductivity of quantum dots. Particularly below threshold, there is a large fraction amount of nonradiative recombination occurring directly in the QD active region. Decreased thermal conductivity results in increased temperature with increasing duty cycle or current. Above threshold, additional thermal effects are largely due to resistive healing from current injection; recombination in the active region is mostly radiative, and hence QD and QW laser behavior above threshold is similar.