Abstract
We report low threshold continuous wave (CW) operation of InAs/AlSb quantum cascade lasers emitting around 20 lm. The laser cavity was made of a plasmon-enhanced dielectric waveguide with cladding layers made of n-InAs. The devices exhibited a threshold current density of 1.38 kA/cm 2 at the maximum temperature of CW operation of 240 K and an output power of 14 mW/facet at T ¼ 80 K. In pulsed mode, the lasers operated up to 380 K with a threshold current density of 1.15 kA/cm 2 at room temperature.