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

Continuous-wave (cw) operation of quantum-cascade lasers emitting at $\lambda \sim 4.8\mu \mathrm{m}$ is reported up to a temperature of $323\mathrm{K}$ . 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 $370\mathrm{mW}$ per facet at $293\mathrm{K}$ , and $38\mathrm{mW}$ per facet at $323\mathrm{K}$ . Room-temperature average power measurements are demonstrated with over $600\mathrm{mW}$ per facet at 50% duty cycle with over $300\mathrm{mW}$ still observed at 100% (cw) duty cycle.