We demonstrate the operation of two optically pumped high-power membrane external-cavity surface-emitting lasers (MECSELs) that emit in 1600–1800 nm spectral region. The region of the MECSEL consisted of eight strained InGaAs quantum wells (QWs) that are enclosed by InGaAlAs barriers. The heterostructures were deposited on InP substrates by molecular beam epitaxy. In order to efficiently dissipate heat, the developed MECSEL technology requires etching-off the epitaxial substrate and bonding two diamond heat spreaders on both sides of membrane. Maximum output powers of 1.6 W at 1640 nm and 2.1 W at 1760 nm were achieved. The mount temperatures were -6°C in both cases. The introduction of a birefringent filter into the resonator of the 1760 nm emitting laser produced a 133-nm wavelength tuning range, from 1695 nm to 1828 nm.
Electronic structure of functional region of the interband cascade infrared photodetector designed to operate with cut-off wavelength of ~10.7 μm is calculated using second nearest neighbor sp3s* tight binding model with spin-orbit interactions. The effective bandgaps and alignment of the band edges are presented. Lattice mismatch of each region to the GaSb substrate is determined. The influence of InAs incorporation into the InSb interfacial layer is investigated. It is shown that up to 5% InAs addition to InSb interface in InAs/GaSb superlattice absorber is allowed if efficient carrier transport is to be kept. Furthermore, interface of up to x=2% InAsxSb1-x can be used in the proposed InAs/AlSb superlattice intraband relaxation region to keep its proper operation.
Measurements of low-frequency noise of type-II superlattice detectors designed for mid-IR wavelengths are used to determine noise limitations, calculate the real detectivity, and study 1/f noise-current correlations in these devices. No 1/f noise connected to the diffusion current is found as opposed to the generation-recombination, shunt, and tunneling currents. The contribution from the shunt current to 1/f noise can be so large that shunt-originated noise dominates in the high-temperature region, in which current is limited by the generation-recombination and diffusion components. It is also demonstrated that devices made of type-II superlattice contain traps generating random processes with thermally activated kinetics, and the activation energies of these traps are determined.
The essential steps in simulations of modern separate absorption, grading, charge, and multiplication avalanche photodiode and their results are discussed. All simulations were performed using two commercial technology computer-aided design type software packages, namely Silvaco ATLAS and Crosslight APSYS. Comparison between those two frameworks was made and differences between them were pointed out. Several examples of the influence of changes made in individual layers on overall device characteristics have been shown. Proper selection of models and their parameters as well as its significance on results has been illustrated. Additionally, default values of material parameters were revised and adequate values from the literature were entered. Simulated characteristics of optimized structure were compared with ones obtained from measurements of real devices (e.g., current-voltage curves). Finally, properties of crucial layers in the structure were discussed.