InAs-Based Quantum Cascade Lasers with Extremely Low Threshold

We report InAs-based quantum cascade lasers (QCLs) operating near 14 µm with a threshold current density Jth as low as 0.6 kA/cm2 at room temperature. The threshold obtained is lower than the Jth of the best reported InP-based QCLs to date without facet treatment. The achieved performance improvement is partially due to an increased separation between the upper transition level and the next one in the active quantum wells of the employed QCL design.