Single-spatial-mode semiconductor VCSELs with a nonplanar upper dielectric DBR

Single-spatial-mode semiconductor vertical-cavity surface-emitting lasers (VCSELs) with a non-planar upper (output) dielectric distributed Bragg reflector (DBR) for the 850 nm spectral region are fabricated. The suggested design provides stable single-mode generation in the entire range of working currents, limited by overheating of the active region. Devices with intracavity contacts and a comparatively large current-aperture diameter (5–6 μm) exhibit single-mode lasing at a wavelength of 840–845 nm in the continuous-wave mode at room temperature with threshold currents of 1.2–1.3 mA, a differential efficiency of 0.5–0.55 mW mA^?1, and anoutput power of up to 2 mW.     

Effect of the severe plastic deformation temperature on the diffusion properties of the grain boundaries in ultrafine-grained metals

A model is proposed to explain the effect of the severe plastic deformation (SPD) temperature on the diffusion properties of the grain boundaries in ultrafine-grained (UFG) metals and alloys. It is shown that an increase in the SPD temperature in UFG metals leads to an increase in the activation energy of grainboundary diffusion from (3–5)k _B T _m, which corresponds to the diffusion parameters of nonequilibrium grain boundaries, to (8–10)k _B T _m, which corresponds to the diffusion parameters of equilibrium grain boundaries (k _B is the Boltzmann constant, T _m is the melting temperature). The dependence of the activation energy of grain-boundary diffusion on the SPD temperature is found to be determined by the kinetics of the competing processes of defect accumulation at grain boundaries and the diffusion accommodation of defects.     

Propagation of single flux quantum pulse of superconducting transmission line

Josephson tunnel junction switching by single flux quantum (SFQ) pulses generated by a two-junction interferometer and propagated on a superconducting transmission line have been investigated experimentally and by numerical simulation. High current density tunnel junctions have been used to enhance voltage SFQ pulse amplitudes and reduce junction damping parameters. The measured effective amplitudes of SFQ pulses allow an evaluation of the applicability of transmission lines to SFQ logic circuits and Josephson samplers.     

Study of the deactivation mechanisms for some constructional steels by secondary-ion mass spectrometry

Conclusions Dense corrosion layers on steels 48TS, 2Kh13, and 12Kh18N10T obtained under conditions simulating the first loop in a boron-regulated reactor are depleted in the alloying elements at the surface. Treatment with boric permanganate (pH7.4) leads to selective dissolution of the iron and partial dissolution of the iron-rich surface layer of the model oxide. Triloncitrate recipes dissolve the oxide layers efficiently when these are enriched in iron but are ineffective in dissolving chromium-bearing oxide layers.Because of these features, the performance in removing model oxide by treatment with these transformable deactivating recipes decreases in the series 48TS, 2Kh13, and 12Kh18N10T. Therefore, a basic problem in devising effective method of deactivating constructions containing low-alloy, stainless, and chromium steels is the prevision in the deactivating solution of conditions favoring relatively uniform dissolution of the oxides of iron (nickel) and the oxides of chromium. None of the recipes considered above satisfies this requirement. Further research is in hand on the possibility of realizing these conditions.Translated from Atomnaya Énergiya, Vol. 53, No. 3, pp. 171–174, September, 1982.     

Influence of Output Optical Losses on the Dynamic Characteristics of 1.55-μm Wafer-Fused Vertical-Cavity Surface-Emitting Lasers

Semiconductors - The results of studying the dynamic characteristics of 1.55-μm single-mode vertical-cavity surface-emitting lasers (VCSELs) formed by the fusion of wafers of high-quality...