The design and fabrication of metamorphic periodic heterostructures containing InAsSb layers with controllable modulated Sb composition and well‐regulated band alignments are reported. The bandgap energy of ordered alloy can be much smaller than that in bulk InAsSb with any Sb content. The modulation period is determined by the thicknesses of the strain compensated InAsSb _x /InAsSb _y pairs grown on a virtual GaIn _z Sb substrate with a given lattice constant. The experiment shows that the deviation of the modulation period from ∼2.3 to ∼5.5 nm leads to the shift of the maximum of 20 K photoluminescence from 12.9 to 19.6 µm. It is concluded that the growth of strain compensated InAsSb _x /InAsSb _y on virtual substrates allows developing narrow bandgap III–V materials with various bandgap energies.

The passively mode-locked type-I quantum well cascade diode lasers operating near 2.7 and 3.2 μm generated trains of the ∼10 ps long pulses with average power up to 10 mW. The devices based on laser heterostructures with reinforced carrier confinement required increased reverse bias voltages applied to absorber sections to operate in mode-locked regime. The autocorrelation measurements showed that lasers generated strongly chirped pulses with temporal width an order of magnitude above transform limit. The application of the external feedback led to narrowing of the laser emission spectra accompanied by an order of magnitude reduction of the intermodal beat note linewidth. The multiheterodyne beat notes have been observed for devices stabilized by external feedback.

Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in a spectral region from 1.9 to 3.3 μm. Carrier recycling between quantum well gain stages was realized using band-to-band tunneling in GaSb/AlSb/InAs heterostructure complemented with optimized electron and hole injector regions. Coated devices with an ~100-μm-wide aperture and a 3-mm-long cavity demonstrated continuous wave (CW) output power of 1.96 W near 2 μm, 980 mW near 3 μm, 500 mW near 3.18 μm, and 360 mW near 3.25 μm at 17–20 °C—a nearly or more than twofold increase compared to previous state-of-the-art diode lasers. The utilization of the different quantum wells in the cascade laser heterostructure was demonstrated to yield wide gain lasers, as often desired for tunable laser spectroscopy. Double-step etching was utilized to minimize both the internal optical loss and the lateral current spreading penalties in narrow-ridge lasers. Narrow-ridge cascade diode lasers operate in a CW regime with ~100 mW of output power near and above 3 μm and above 150 mW near 2 μm.

A design for GaSb-based type-I quantum well diode lasers with an AlGaInAsSb/GaInAsSb active region, GaSb and AlGaAsSb separate confinement layers, and an AlSb/InAs hole stopper is proposed. The suppression of carrier recombination outside of the active region leads to improved laser efficiency and temperature stability. At a heatsink temperature of 17°C, the 2-mm-long, 100-μm-wide, anti-/high-reflection coated devices demonstrate threshold current densities of ~ 350 A/cm² and emit ~ 220 mW of continuous wave output power at 3.15 μm.

We have experimentally studied the interband photoluminescence spectra of InGaAsSb/AlGaAsSb quantum wells with different well widths and calculated the dependence of the charge carrier concentration participating in radiative recombination on the pumping intensity. The results of theoretical calculations appeared to be in a good agreement with the experimental relationship between the photoluminescence intensity at spectral maxima and the pumping intensity. The resonant Auger recombination involving two holes and one electron and causing a significant decrease in the charge carrier concentration was detected in one of the samples. Recommendations for suppressing the harmful nonradiative Auger recombination were made to increase the operating efficiency of semiconductor injection lasers at wavelengths of about 3 μm.