High-power λ∼9.5μm quantum-cascade lasers operating above room temperature in continuous-wave mode

We report high-power continuous-wave (cw) operation of $\lambda \sim 9.5\mathrm{\mu }\mathrm{m}$ quantum-cascade lasers to a temperature of $318\mathrm{K}$ . A high-reflectivity-coated $19\text{-}\mathrm{\mu }\mathrm{m}\text{-}\mathrm{wide}$ and 3-mm-long device exhibits cw output powers as high as $150\mathrm{mW}$ at $288\mathrm{K}$ and still $22\mathrm{mW}$ at $318\mathrm{K}$ . In cw operation at $298\mathrm{K}$ , a threshold current density of $1.57\mathrm{kA}∕{\mathrm{cm}}^2$ , a slope efficiency of $391\mathrm{mW}∕\mathrm{A}$ , and a maximum wall-plug efficiency of 0.71% are obtained. In pulsed operation, a maximum average power of $317\mathrm{mW}$ is achieved at 49% duty cycle. The emission wavelength in cw mode is shifted from $9.524\mathrm{\mu }\mathrm{m}$ at $288\mathrm{K}$ to $9.547\mathrm{\mu }\mathrm{m}$ at $313\mathrm{K}$ near $1.05\mathrm{A}$ drive current with a temperature tuning coefficient of $0.92\mathrm{nm}∕\mathrm{K}$ .