THz lasers based on narrow-gap semiconductors

We report recent results on THz lasing in PbSnSe and HgCdTe. The wavelength of 46.3 microns was achieved in a PbSnSe laser with diffusion p-n junction. In HgCdTe waveguide structure with quantum wells (QWs) we demonstrate twofold increase in stimulated emission (SE) wavelength compared to previous works. The threshold pumping intensity is as low as 0.12 kW/cm2 for the SE wavelength of 9.5 microns. Molecular beam epitaxy of HgCdTe allows reproducible growth of thin QWs that can provide the “symmetrical” energy-momentum laws in conduction and valence bands, like in bulk PbSnSe, and thus suppress Auger recombination. Further prospects concerning THz lasers based on HgCdTe QWs are discussed.