Room-temperature, continuous-wave, single-mode quantum-cascade lasers at λ≃5.4μm

We demonstrate room-temperature, single-mode, continuous-wave operation of a $\lambda \simeq 5.4\mu \mathrm{m}$ quantum-cascade laser up to the temperature of $30°\mathrm{C}$ . Processing is done using standard lithography in a ridge waveguide mounted junction-up. The active region is based on a bound-to-continuum transition. The high performances were achieved with a low active region doping and a thick electroplated gold deposition, resulting in a characteristic temperature of $T_0=155\mathrm{K}$ in continuous-wave with a threshold current density of $j_{\mathrm{th}}=2.05\mathrm{kA}∕{\mathrm{cm}}^2$ at $300\mathrm{K}$ .