Low-threshold continuous-wave operation of quantum-cascade lasers grown by metalorganic vapor phase epitaxy

We report on the realization of $\mathrm{In}\mathrm{Ga}\mathrm{As}∕\mathrm{In}\mathrm{Al}\mathrm{As}$ quantum-cascade lasers grown by metalorganic vapor phase epitaxy operating in continuous wave with low-threshold current densities at temperatures as high as $188\mathrm{K}$ . Threshold current densities of $950\mathrm{A}∕{\mathrm{cm}}^2$ and output powers of $125\mathrm{mW}$ are measured at $80\mathrm{K}$ , while $3\mathrm{mW}$ of continuous output power are measured at $180\mathrm{K}$ , with a threshold of $2.5\mathrm{kA}∕{\mathrm{cm}}^2$ . In pulsed mode, peak output powers of more than $0.4\mathrm{W}$ were obtained at $80\mathrm{K}$ and of $160\mathrm{mW}$ at $300\mathrm{K}$ with thresholds of $700\mathrm{A}∕{\mathrm{cm}}^2$ and $2.75\mathrm{kA}∕{\mathrm{cm}}^2$ , respectively.