THz and Multi THz Lasers Based on Heterostructure with HgCdTe/CdHgTe with Quasirelativistic Dispersion Laws

Thanks to the industry of infrared (IR) detectors the quality of Hg(Cd)Te/CdHgTe heterostructures is approaching the quality of their A3B5 counterparts. Hg(Cd)Te/CdHgTe quantum wells (QWs) deliver a widely (from 0 to over 1200 meV) variable bandgap, while maintaining the ability to tailor the carrier energy spectrum. We show that in the long-wavelength part of mid-IR Hg(Cd)Te/CdHgTe QWs offer the quasi-relativistic carrier dispersion law that suppresses the Auger recombination, enabling stimulated emission (SE) up to 31 µm, and laser generation up to 24 µm in the temperature range from 10 to 80 K. The record wavelength of 31 µm (inaccessible for existing cascade lasers) is achieved by a peculiar design of the structure utilizing the reflection of the waveguide mode from the substrate near the Reststrahlen band of GaAs. In the atmospheric transparency window of 3–5 µm, we were able to mitigate not only bulk-like Auger recombination but also QW-specific thresholdless Auger processes associated with non-radiative transitions into barriers. As a result, optically pumped laser action on whispering gallery modes was achieved in the vicinity of 4 µm up to 230 K.