Low-Threshold High-Temperature Operation of ～7.4μm Quantum Cascade Lasers

We report low-threshold high-temperature operation of 7.4μm strain-compensated InGaAs/InAlAs quantum cascade lasers (QCLs). For an
uncoated 22-μm-wide and 2-mm-long laser, the low-threshold current
densities, i.e. 0.33kA/cm² at 81K in pulsed mode and 0.64kA/cm² at 84K in cw mode, are realized. High-temperature operation of uncoated devices, with a high value of 223K, is achieved in cw mode.