Discrete energy level separation and the threshold temperature dependence of quantum dot lasers

Data are presented on one- and two-stack InAs quantum dot lasers that have reduced temperature sensitivity of their lasing threshold. Adjustment of dot size and composition is used to increase the energy separation between the ground and first excited radiative transition energies to 104 meV, with a dot density of ∼3.1×1010 cm−2. The one- and two-stack lasers show broad area as-cleaved room temperature threshold current densities as low as 43 and 35 A/cm2, respectively. The wide energy separation between the ground and first excited radiative transitions leads to significant improvements in the temperature sensitivity of threshold.