Continuous-wave operation of λ∼4.8μm quantum-cascade lasersat room temperature

Continuous-wave (cw) operation of quantum-cascade lasers emitting at λ∼4.8μm is reported up to a temperature of 323K. Accurate control of layer thickness and strain-balanced material composition is demonstrated using x-ray diffraction. cw output power is reported to be in excess of 370mW per facet at 293K, and 38mW per facet at 323K. Room-temperature average power measurements are demonstrated with over 600mW per facet at 50% duty cycle with over 300mW still observed at 100% (cw) duty cycle.