We report on stimulated emission at wavelengths up to 19.5 μm from HgTe/HgCdTe quantum well heterostructures with wide‐gap HgCdTe dielectric waveguide, grown by molecular beam epitaxy on GaAs(013) substrates. The mitigation of Auger processes in structures under study is exemplified, and the promising routes towards the 20–50 μm wavelength range, where HgCdTe lasers may be competitive to the prominent emitters, are discussed.

We report stimulated emission in the 2.8–3.5 μm wavelength range from HgTe/CdHgTe quantum well (QW) heterostructures at temperatures available with thermoelectric cooling. The structures were designed to suppress the Auger recombination by implementing narrow (1.5 – 2 nm wide) QWs. We conclude that Peltier cooled operation is feasible in lasers based on such structures, making them of interest for spectroscopy applications in the atmospheric transparency window from 3 to 5 μm.

The observation of a stimulated emission at interband transitions in monocrystalline n-InN layers under optical pumping is reported. The spectral position of the stimulated emission changes over a range of 1.64 to 1.9 μm with variations of free electron concentration in InN layers from 2·10¹⁹ cm⁻³ to 3·10¹⁷ cm⁻³. The main necessary conditions for achieving the stimulated emission from epitaxial InN layers are defined. In the best quality samples, a threshold excitation power density is obtained to be as low as 400 W/cm² at T = 8 K and the stimulated emission is observed up to 215 K. In this way, the feasibility of InN-based lasers as well as the potentials of crystalline indium nitride as a promising photonic material are demonstrated.

We report on the stimulated emission (SE) from HgTe/CdHgTe quantum well (QW) heterostructures up to 240 K at 3.7 μm wavelength. Based on the temperature dependence of the SE threshold, a total Auger recombination (AR) coefficient of 10⁻²⁷ cm⁶/s has been deduced for HgTe/CdHgTe QWs, which is much lower than that for bulk HgCdTe with the same bandgap and indicates suppression of (threshold) AR processes due to the symmetry of carrier dispersion curves. We demonstrate that QW-specific, non-threshold AR contributes strongly to the temperature quenching of laser action from HgTe/CdHgTe QWs. We expect, however, that the above processes may be partially suppressed via introduction of wide-gap CdHgTe barrier layers with a [Cd] fraction of 80% or higher. In this case, lasing up to at least 270 K at 3.7 μm wavelength seems feasible.

GaAs-based microdisk lasers with an active region representing a dense array of indium-rich islands (InGaAs quantum well-dots) were studied using direct small-signal modulation. We demonstrate that using dense arrays of InGaAs quantum well-dots enables uncooled high-frequency applications with a GHz-range bandwidth for microdisk lasers. A maximum 3 dB modulation frequency of 5.9 GHz was found in the microdisk with a radius of 13.5 μm operating without a heatsink for cooling. A modulation current efficiency factor of $1.5\mathrm{GHz}/{\mathrm{mA}}^{1/2}$ was estimated.

We present detailed theoretical analysis of nonradiative Auger recombination in narrow-gap mercury-cadmium-telluride quantum wells (HgCdTe QWs). We suggest a microscopic model to calculate Auger recombination rates in the QWs with different Cd fraction as functions of non-equilibrium carrier density with account to the complex band dispersions and wavefunctions, degenerate carrier statistics, and screening effects. Our model is validated by the comparison of measured photoconductivity kinetics with the simulated curves. Furthermore, we use the developed calculation technique to evaluate different designs of HgCdTe/CdHgTe QWs for the far-IR emitters. In particular, we consider a series of QWs with the fixed bandgap of 40 meV (lasing wavelength about 30 μm) and find out that lasing may be favored in the QWs with moderate (6%–9%) cadmium content and not in the pure binary HgTe QWs, which is in contrast to intuitive expectations within threshold energy concept for Auger recombination. Though cadmium-free QWs do provide the highest possible Auger threshold energies, Cd-containing QWs feature much more efficient screening of Coulomb potential (and so Auger interaction) by free charge carriers. The latter effect contributes decisively into the suppression of Auger processes at low temperatures and high carrier concentrations.