Stimulated emission of plasmon-LO mode in narrow gap HgTe/CdHgTe quantum wells

International audienc

Auger recombination in narrow gap HgCdTe/CdHgTe quantum well heterostructures

International audienc

Coherent Emission in the Vicinity of 10 THz due to Auger-Suppressed Recombination of Dirac Fermions in HgCdTe Quantum Wells

International audienceThe discovery of Dirac fermions in a number of 2D and 3D materials boosted the solid-state research in an unprecedented way. Among the many hopes of using their exceptional physical properties, it has been argued that their reduced nonradiative losses would allow graphene to compete with quantum cascade lasers (QCLs) in the race for terahertz (THz) emitters. Unfortunately, the nonradiative Auger recombination (AR) process is still active for massless fermions in gapless graphene. However, for massive Dirac fermions, AR can be entirely suppressed below a certain threshold of the carrier’s kinetic energy that depends on the nonparabolicity and the symmetry of the electron and hole dispersions. In this work, by finely tuning the band structure of HgCdTe quantum wells hosting massive Dirac fermions, we set the electronic system below this threshold and demonstrate that the carrier recombination is purely radiative. A coherent interband emission reaching 9.6 THz, that is to say outside the spectral range of current QCLs, is measured under these conditions, opening the way to lossless interband THz emitters

Stimulated Emission up to 2.75 µm from HgCdTe/CdHgTe QW Structure at Room Temperature

Heterostructures with thin Hg(Cd)Te/CdHgTe quantum wells (QWs) are attractive for the development of mid-infrared interband lasers. Of particular interest are room-temperature operating emitters for the short-wavelength infrared range (SWIR, typically defined as 1.7–3 μm). In this work, we report on the observation of stimulated emission (SE) in the 2.65–2.75 µm wavelength range at room temperature in an optically pumped HgCdTe QW laser heterostructure. We study a series of three samples with lengths ranging from 2.5 to 7 mm and discuss the effects related to the non-uniformity of the excitation beam profile. SE threshold intensity and the magnitude of pump-induced carrier heating are found to be effectively dependent on the chip size, which should be accounted for in possible designs of HgCdTe-based optical converters. We also pay attention to the problem of active medium engineering in order to push the SE wavelength towards the 3–5 µm atmospheric window and to lower the SE threshold