Статья посвящена синтезу многослойных диэлектрических отражательных дифракционных решеток, с высокой эффективностью обеспечивающих спектральное сложение пучков с различной длиной волны в заданном дифракционном порядке. Приводятся результаты решения задачи синтеза многослойных диэлектрических дифракционных решеток, обеспечивающих спектральное сложение в первом или минус первом порядке дифракции. Кроме того, решается задача синтеза для таких решеток с учетом возможных технологических ограничений на высоту профиля (глубину травления). Решение задачи синтеза проводится путем минимизации зависящего от параметров решетки целевого функционала методом Нелдера-Мида. Решение прямой задачи на каждом шаге минимизации осуществляется при помощи комбинации неполного метода Галеркина и метода матриц рассеяния. The paper is devoted to the synthesis of multilayer dielectric reflection diffraction gratings providing high-efficiency spectral combining of the beams with different wavelengths in a given diffraction order. The results are presented for solving the synthesis problems for multilayer dielectric diffraction gratings providing spectral combining in the first or minus first diffraction order. Besides, the synthesis problem for such gratings is solved with account taken of possible technological constraints imposed by the height of the grating profile (etch depth). The solution of the synthesis problem is obtained by means of Nelder-Mead minimization of the merit function depending on the grating parameters. At each minimization step the direct problem is solved using a combination of the incomplete Galerkin method and scattering matrix method.

The paper is devoted to the synthesis of multilayer dielectric reflection diffraction gratings providing high-efficiency spectral combining of the beams with different wavelengths in a given diffraction order. The results are presented for solving the synthesis problems for multilayer dielectric diffraction gratings providing spectral combining in the first or minus first diffraction order. Besides, the synthesis problem for such gratings is solved with account taken of possible technological constraints imposed by the height of the grating profile (etch depth). The solution of the synthesis problem is obtained by means of Nelder-Mead minimization of the merit function depending on the grating parameters. At each minimization step the direct problem is solved using a combination of the incomplete Galerkin method and scattering matrix method.

In this work, we present the directions of further development of a prototype of television navigation system (TNS) for course setting in precision orientation of vehicles during their motion guided by the video and audio information transmitted via radio channel to the receiving onboard instrumentation. We discuss the issues of precision of TNS-guided course setting and possibilities for TNS and GLONASS/GPS system coupling using digital navigation maps with the ship coordinate determination simultaneously in two independent channels, thus making the ship navigation much more reliable and safe. A key salient feature of TNS is that the ship can be navigated within the line of sight at distances as long as 20 km at up to 1-m SD of cross-track deviation from preset course, and those observations are ensured under the conditions of degraded visibility in the atmosphere. Capabilities of “Vzlet” TNS are explored for aircraft taxiing, take-off, and landing on the basis of preliminary flight tests. Other potential TNS applications are discussed.

In this work, we describe a prototype of television system of course setting (TSCS) in precision orientation of vessel moving along straight-line directions in accordance with video and acoustic information transferred via radio channel to receiving instrumentation. A key salient feature of TSCS is that the ship can be navigated within the line of sight at distances as long as 20 km at up to 1-m SD of cross-track deviation from preset course, and that observations are possible under the conditions of decreased atmospheric transparency. The components of receiver-indicator and inshore part of TSCS are listed. The main technical characteristics of instrumentation and TSCS capabilities are shown. Prospects of further development are indicated.

Thin cadmium sulfide films grown by pulsed laser deposition on crystalline and amorphous substrates have been shown to consist of a mixture of a cubic (sphalerite structure) and a hexagonal (wurtzite structure) phase. We have demonstrated the possibility of controlling the percentages of the hexagonal and cubic phases in cadmium sulfide films by varying pulsed laser deposition parameters. Varying the deposition parameters allows one to control the optical and structural parameters and surface morphology of thin cadmium sulfide films.

SnO2:Sb thin films are grown by pulsed laser deposition with high-speed particle separation on quartz-glass substrates without post-deposition annealing under different deposition conditions in the range of the energy densities on the target from 3.4 to 6.8 J/cm2. Their optical, structural, and electrical properties are studied. It is found that the energy density on the target affects the SnO2:Sb film conductivity and transmittance. The optimum conditions of film growth by the droplet-free pulsed laser deposition method are determined. A resistivity minimum of 1.2 × 10–3 Ω cm is observed at an energy density on the target of 4.6 J/cm2, a substrate temperature of 300°C, and an oxygen pressure of 20 mTorr in the vacuum chamber during deposition.

Методом импульсного лазерного осаждения со скоростной сепарацией частиц на подложках кварцевого стекла без последующего отжига получены тонкие пленки SnO2 : Sb при различных условиях осаждения в диапазоне плотности энергии на мишени от 3.4 до 6.8 Дж/см2. Исследованы их оптические, структурные и электрические свойства. Установлено, что плотность энергии на мишени влияет на проводимость и пропускание пленок SnO2 : Sb. Определены оптимальные условия получения пленок бескапельным методом импульсного лазерного осаждения. Минимум удельного сопротивления 1.2·10-3 Ом·см наблюдался при плотности энергии на мишени 4.6 Дж/см2, температуре подложки 300oC и давлении кислорода в вакуумной камере в процессе осаждения 20 мТорр. DOI: 10.21883/FTP.2017.03.44220.8387

A hybrid numerical technique based on a combination of the finite element method (FEM) and the scattering matrix method is applied to a wave diffraction problem on multilayer gratings. The grating represents a composite structure consisting of two main subdomains. The first one comprises a diffraction grating with a given groove shape. The second subdomain includes a set of homogenous dielectric layers, which form a multilayer reflection coating. The scattering matrix components of the diffraction grating are obtained by FEM and further transferred to the scattering matrix of the second subdomain. By means of the scattering matrix method the matching of the solutions at the interface of two subdomains is performed. The suggested hybrid method is applied to one-dimensional multilayer gratings with different groove shapes. The computational cost and the convergence rate of the proposed method are estimated. The results are compared with those, obtained by other numerical methods.

The thin SnO2:Sb films have been produced on flexible organic polyethyleneterephthalate substrates of room temperature by the droplet-free pulsed laser deposition method. Their optical and electric properties have been investigated. It has been established that energy density on the target influences the conductivity and transmission of the SnO2:Sb films. The optimum conditions of film production at the room temperature have been determined. The minimum resistivity of the produced films (ρ ~ 5 × 10−3 Ohm cm) was observed at the energy density of 5 J/cm2 on the target and at the oxygen pressure of 20 mTorr in the vacuum chamber during the deposition. The application of post-growth laser annealing at the energy density on the film from 20 to 40 mJ/cm2 for thin SnO2:Sb films produced under various conditions of deposition causes a 5 to 20 times decrease in the resistivity of the low-resistance SnO2:Sb films, and a 300 times decrease in the resistivity of high-resistance ones.

Рассматривается математическая модель процесса дифракции волны на локальной неоднородной многослойной вставке, помещенной в регулярный прямоугольный волновод. Приводится описание алгоритма численного решения соответствующей задачи дифракции, основанного на применении гибридных численных и численно-аналитических методов. В частности, описываются гибридные методы, основанные на совместном применении неполного метода Галеркина в комбинации с методом конечных разностей и методом матриц переноса. Приводится сравнительный анализ рассмотренных методов, в том числе анализ эффективности их применения для моделирования процесса дифракции волны на многослойной неоднородной вставке в волноводе. A mathematical model of wave diffraction on a local inhomogeneous multilayer inset placed inside a rectangular waveguide is considered. An algorithm for the numerical solution of the corresponding diffraction problem based on the application of hybrid numerical and numerical-analytical methods is described. In particular, the hybrid methods based on the joint application of the incomplete Galerkin's method together with the finite difference method and the transfer matrix method are discussed. A comparative analysis of the described methods is given, including an efficiency analysis of these methods in application to modeling the wave diffraction on a multilayer inhomogeneous inset in a waveguide.

The electroluminescent properties of a light-emitting diode n -GaSb/ n -InGaAsSb/ p -AlGaAsSb heterostructure with high potential barriers are studied in the temperature range of 290–470 K. An atypical temperature increase in the power of the long-wavelength luminescence band with an energy of 0.3 eV is experimentally observed. As the temperature increases to 470 K, the optical radiation power increases by a factor of 1.5–2. To explain the extraordinary temperature dependence of the radiation power, the recombination and carrier transport processes are theoretically analyzed in the heterostructure under study.

Nanocrystalline antimony-doped ([Sb]/([Sb] + [Sn]) = 0–2 at %) SnO 2 powders have been synthesized by coprecipitation from solution. The composition, crystal structure, and microstructural parameters of the powders, as well as the antimony distribution in them, have been studied by laser mass spectrometry, X-ray diffraction, low-temperature nitrogen adsorption measurements, and IR spectroscopy. The reaction of the synthesized materials with oxygen has been studied in situ by electrical conductance measurements. Oxygen chemisorption on the surface of unmodified SnO 2 leads to predominant formation of the molecular species O 2(ads) - . Increasing the Sb concentration in the SnO 2 ‹Sb› samples increases the fraction of the monatomic species O 2(ads) - , which can be explained in terms of a combination of crystal-chemical and electronic factors.

We report on superlinear electroluminescent structures based on AlSb/InAs1-xSbx/AlSb deep quantum well grown by MOVPE on n-GaSb:Te substrate. Dependence of the electroluminescence (EL) spectra and optical power on the drive current in nanoheterostructures with AlSb/InAs1-xSbx/AlSb quantum well at 77 – 300 K temperature range was studied. Intensive two-band superlinear EL in the 0.5 - 0.8 eV photon energy range was observed. Optical power enhancement with the increasing drive current at room temperature is caused by the contribution of the additional electron-hole pairs due to the impact ionization by the electrons heated at the high band offset between AlSb and the first electron level Ee1 in the InAsSb QW. Study of the EL temperature dependence at 90 – 300 K range enabled us to define the role of the first and second heavy hole levels in the radiative recombination process. It was shown that with the temperature decrease, the relation between the energies of the valence band offset and the second heavy hole energy level changes due to the temperature transformation of the energy band diagram. That is why the EL spectrum revealed radiative transitions from the first electron level Ee1 to the first hole level Eh1 in the whole temperature range (90 – 300 K) while the emission band related with the transitions to the second hole level occurred only at T < 200 K.

A mathematical model of wave diffraction from a one-dimensional multilayer periodic grating is considered. A rigorous mathematical statement is given for the problem where partial radiation conditions are used for domain confinement. A complete formulation of the numerical algorithm based on a combination of the incomplete Galerkin method and the scattering-matrix method is presented. The algorithm’s convergence rate and computational complexity are analyzed and the optimal values of the computational parameters are recommended.