A Low Threshold Current Density InAs/AlGaSb Superlattice Quantum Cascade Laser Operating at 14 µm

We report a low threshold current density InAs/AlGaSb superlattice quantum cascade laser operating at 14 µm. In order to reduce the threshold current density, InAs/AlGaSb superlattice structures providing large oscillator strength and fast carrier depopulation are used for the active layers. Observed threshold current density at 80 K is 0.92 kA/cm 2 , which is about 5 times lower than that of the first InAs/AlSb quantum cascade laser reported earlier. This is among lowest threshold current density of quantum cascade lasers operating in the mid-infrared spectrum region.