Novel split-well resonant-phonon terahertz quantum cascade laser supporting clean four-level system.

We present a novel terahertz quantum cascade laser (THz QCL) scheme supporting a clean four-level system, ‘four’ being the number of the active laser states, as verified by the negative differential resistance (NDR) observed all the way up to room temperature. In this study, we analyze and discuss the temperature performance of this new design. Experimental as well as theoretical work was performed to analyze the effects of the doping density as well as the impact of the different scattering mechanisms.