Влияние параллельного слоям магнитного поля на фототок в GaAs/AlAs p-i-n-структурах

The behavior of the photocurrent in GaAs / AlAs p-i-n heterostructures is studied in a magnetic field parallel to the heterolayers in the wavelength range from 395 to 650 nm. A strong dependence of the non-oscillating component of the photocurrent on the radiation wavelength associated with the suppression of the diffusion current by the magnetic field was found. It is shown that the behavior of the oscillating component of the photocurrent in a magnetic field does not depend on the wavelength of light and is determined by the transfer of electrons through the dimensional quantization level in a triangular near-barrier well. It is shown that the suppression of the oscillating component by the magnetic field is due to the smearing of the level in the triangular well due to the motion of electrons parallel to the walls of the well and perpendicular to the magnetic field.

Influence of laser texturing on tribological properties of DLC coatings

The work presents the use of laser texturing of DLC coatings to improve tribological properties. The coatings were applied by the PVD method to the rings made of 4H13 steel. The surface texturing was performed with the TruMICRO 5325c picosecond laser with the radiation wavelength λ = 343 nm. The surface microstructure analysis, surface microgeometry and microhardness measurements and tribological tests were carried out. The problem presented in the paper can be used to extend the knowledge of the areas of application of DLC coatings, especially in sliding friction pairs.

Feasibility of X-ray beam nanofocusing with compound refractive lenses

A more general analytical theory of X-ray beam propagation through compound refractive lenses (CRLs) than the earlier study by Kohn [(2003). JETP, 97, 204–215] is presented. The problem of nanofocusing with CRLs is examined in detail. For a CRL with a relatively large aperture the focusing efficiency is limited by the radiation absorption in the lens material. The aperture does not affect the focusing process and it is replaced by the effective aperture. The X-ray transverse beam size at the focus is then by a factor of γ = β/δ times smaller than the transverse beam size just behind the CRL. Here, δ and β are the real and imaginary parts of the CRL material refractive index n = 1 − δ + iβ. In this instance, to improve focusing efficiency, it is advantageous to decrease the CRL aperture and increase the photon energy E. However, with increasing photon energy, the material absorption decreases, which results in the CRL aperture impact on the transverse beam size. The latter leads to the fact that with a proper CRL length the beam size is independent of both the aperture and photon energy but depends only on the CRL material electron density and is approximately equal to w c = λ/(8δ)1/2, where λ denotes the radiation wavelength, as predicted by Bergemann et al. [(2003). Phys. Rev. Lett, 91, 204801].

Термофотоэлектрические GaSb-преобразователи излучения инфракрасных селективных эмиттеров

In this study, GaSb-based thermophotovoltaic converters for selective mantle-type Y2O3-based emitter covered with rare earth oxides Er2O3 / Yb2O3 have been investigated. Matching the spectral response of the converters with the peaked emitter radiation wavelength λ = 1540 nm provides a thermophotovoltaic conversion efficiency of more than 26% (0.4 W).

Self-catalyst β-Ga2O3 semiconductor lateral nanowire networks synthesis on the insulating substrate for deep ultraviolet photodetectors

Monoclinic gallium oxide (β-Ga2O3) is a super-wide bandgap semiconductor with excellent chemical and thermal stability, which is an ideal candidate for detecting deep ultraviolet (DUV) radiation (wavelength from 200 nm to 280 nm).

Оптические и структурные свойства нанопленок палладия в атмосфере водорода

The crystal structure and optical properties of thermal-vacuum deposited palladium nanolayers at the thickness range of 10-130 nm was studied. It was found that Pd nanolayers are polycrystalline and the value of an average crystallite size depends on the layer thickness. The optical transparency of Pd nanolayers was investigated on the radiation wavelength about 0.95 μm in air and in hydrogen medium (100 vol.%). It was experimentally found that both in air and in hydrogen medium the optical transparency of Pd nanolayers in the thickness range of 10-45 nm obeys the Bouger law. The thickness range of Pd thin films suitable for practical application in hydrogen sensor was determined.

Measurement of the absorption coefficient of a periodically poled LiNbO3 crystal at a radiation wavelength of 3 μm

Problem formulating. In the case of nonlinear-optical conversion of high-power laser radiation in nonlinear-optical crystals the optical absorption leads to a nonuniform heating of the crystals, which results in the violation of phase matching conditions, the formation of defects, and optical damage. Goal. Measurements of optical absorption coefficient of the periodically poled lithium niobate (PPLN) crystal at 3 μm radiation wavelength using the piezoelectric resonance laser calorimetry (PRLC). Result. The optical absorption coefficient of PPLN crystal at 3.045 μm radiation wavelength was measured using the piezoelectric resonance laser calorimetry. The value (1.15±0.15) 10⋅ -2cm-1 of absorption coefficient within the measurement error limits was independent of the initial temperature of PPLN and the incident radiation power in the ranges 293–343 K and 0.2–10 W respectively. Practical meaning. The interaction of mid-IR laser radiation with PPLN crystal was studied using the piezoelectric resonance laser calorimetry.

Efficiency of diffraction gratings based on liquid crystals

Wehave recorded geometric-phase diffraction gratingusing the method of holography on a thin layer of dichroic dye. A transmission liquid crystal cell hasbeen assembled inorder to obtain electrically-controlled diffraction in visible range. Also, using software for electrooptical effects modeling wehavecalculated the diffraction efficiency (DE) of the LC-based phase grating as a function of the voltage amplitude at the electrodes,es-timatedtheDEvariation as a function of LCcell thickness, LC materialbirefringenceand the radiation wavelength. The experimental data qualitatively matched with calcu-lation results. 1-st order DE of16% (at 532 nm) has been obtainedforsingle-sided phase grating LC. Furthermore, we have observed the decrease ofDEwith the increase of radiation wavelength.

Clinical and microbiological effectiveness of therapeutic and rehabilitation measures using a low-intensity laser in the practice of an otorhinolaryngologist

The article presents an analysis of the results of using a low-intensity laser in patients with chronic recurrent adenoiditis. Laser therapy was carried out using continuous exposure to red spectrum radiation (wavelength 632 nm, output power from 6 to 8 mW), exposure was performed endonasally for 60 s in each nostril, radiation dose 0.5 J / cm2, the course of treatment consisted of 10 s procedures. It was shown that in the group using laser therapy, the hypertrophy of the pharyngeal tonsil decreased, the number of pathobionts on its surface decreased, and the cellular factors of local antimicrobial defense normalized.