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 do t size and composition is used to increase the energy separation between th e ground and first excited radiative transition energies to 104 meV, with a dot density of similar to 3.1x10(10) 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/cm(2), respectively. The wide energy separation between the ground and first excited radiative transitions leads to significant im provements in the temperature sensitivity of threshold. (C) 2000 American I nstitute of Physics. [S0003-6951(00)00330-2].