2.9 THz quantum cascade lasers operating up to 70K in continuous wave

Abstract

We report the operation of a quantum cascade laser emitting at a $103\mu \mathrm{m}$ wavelength $\left(2.9\mathrm{THz}\right)$ . The active region is based on a bound-to-continuum design allowing a low parasitic leakage current, and a high upper-to-lower-state lifetime ratio. The latter is demonstrated by a pronounced decrease of the differential resistance at threshold, which is visible up to high temperatures, and by a weak temperature dependence of the slope efficiency. At $4\mathrm{K}$ , we report a threshold current density of only $105\mathrm{A}∕{\mathrm{cm}}^2$ both in pulsed and continuous-wave operation, and an emitted peak power of $15\mathrm{mW}$ independent of the duty cycle. Maximum operating temperatures of $95\mathrm{K}$ and $70\mathrm{K}$ are observed in pulsed and continuous wave modes, respectively.