Single-mode lasing at room temperature in quantum-cascade lasers (QCLs) with arched cavity design has been demonstrated. The output optical power in single-mode lasing regime at ~7.7-μm lasing wavelength was above 6 mW with a side-mode suppression ratio of up to 25 dB. The QCL heterostructure for the arched cavities was grown by molecular-beam epitaxy (MBE) based on a heterojunction of In_0.53Ga_0.47As/Al_0.48In_0.52As solid alloys, lattice-matched with InP substrate, and InP layers performing the function of waveguide claddings.

The GaAs-InGaAsP heterointerfaces formation have been studied and optimized using a direct intermolecular wafer bonding (fusion)of an active region heterostructure on an InP substrate and distributed Bragg reflector heterostructures on GaAs substrates for the fabrication of hybrid heterostructures of long-wave vertical-cavity surface-emitting lasers (VCSEL). The heterostructures were grown by solid-source molecular beam epitaxy. It was shown that in the case of incomplete removal of oxide films during the preparation of the wafers before fusion and/or the presence of adsorbed water on the wafer surfaces, the fused interface contains a large number of amorphous inclusions, most likely related to the III-group oxides. Optimization of the formation regimes of a buried tunnel junction on the surface of the InP-based heterostructure made it possible to reduce the surface roughness down to 1 nm and to ensure the thickness of the GaAs-InGaAsP fused interface < 5 nm, with no dislocations or other extended defects in the region of the fused heterointerfaces. The 1.55 μm-range VCSELs fabricated from the hybrid heterostructures created by using the developed technology demonstrate efficient lasing under continuous wave pumping over a wide temperature range, which indicates the high optical quality of the fused heterointerfaces in the VCSEL heterostructure.

The heterostructure of a quantum-cascade laser based on In0.53Ga0.47As/Al0.48In0.52As heteropair lattice matched with the InP was grown by molecular beam epitaxy. InP layers was used to form the optical waveguide. Room temperature lasing in the spectral range of 8 μm in the standard ridge geometry of a Fabry-Perot cavity formed by cleaved facets with peak output optical power of 0.45 W was obtained.

The results of studies on fabrication of vertical-cavity surface-emitting 1.55-μm lasers by fusing AlGaAs/GaAs distributed-Bragg-reflector wafers and an active region based on thin In_0.74Ga_0.26 As quantum wells grown by molecular-beam epitaxy are presented. Lasers with a current aperture diameter of 8 μm exhibit continuous lasing with a threshold current below 1.5 mA, an output optical power of 6 mW, and an efficiency of approximately 22%. Single-mode lasing with a side-mode suppression ratio of 40–45 dB is observed in the entire operating current range. The effective modulation frequency of these lasers is as high as 9 GHz and is limited by the low parasitic cutoff frequency and self-heating.

In this paper we present the study of the features of epitaxial growth highly stressed superlattices based on highly stressed thin InGaAs/InAlAs layers on InP substrates by the molecular beam epitaxy. It was shown that the growth rates of the InGaAs and InAlAs bulk layers lattice-matched to InP substrates do not allow us to precisely determine the growth rates of thin highly stressed InAlAs/InGaAs strain compensated superlattices and the error is about 10 percent. The effect is related to the difference in the growth temperatures of InGaAs and InAlAs bulk layers, which affects the intensity of indium evaporation from the growth surface.