An electrodynamic analysis of the propagation of longitudinal and transverse waves in a periodic 3D grating of ferromagnetic nanoparticles is carried out on the basis of the solution of the characteristic equation, which includes the cells of the scattering matrix of an autonomous block with magnetic nanoinclusions and Floquet channels as a model of the grating cell. On the basis of the solution of a quasi-compatible system of equations obtained by substituting the calculated values of the wave numbers of longitudinal and transverse waves into the dispersion relations, the results of calculating the effective electromagnetic parameters of a 3D grating of ferromagnetic nanoparticles are obtained.
The synthesis of a new sulfonamide by the Diels-Alder reaction is presented. The antibacterial activity of the obtained compound has been studied. New hybrid lyotropic liquid crystal transport systems based on the obtained sulfonamide and a nonionic surfactant-decaethylene glycol monododecyl ether, have been synthesized in an aqueous medium for potential use in biomedicine. The nature of the interactions that occur during the introduction of the sulfonamide obtained in this work into supramolecular organized lyotropic media has been studied. The effect of lanthanide derivative markers and a biological product on the optical and luminescent properties of the resulting systems has been evaluated, which will allow to control the delivery and release of new drugs.
A simulation of remote atmospheric gas analysis in the spectral range near the wavelength of 1572 nm has been performed. The characteristics of a narrow-band thermostable continuous laser diode with an output power of ≤15 mW have been experimentally studied, and the possibility of tuning the laser diode wavelength both within a separate isolated CO2 absorption line and from line to line in the CO2 absorption band has been shown. The possibility of using a laser diode for further work on the creation of a lidar sensor for studying the CO2 content in the atmosphere has been shown.
In this work, the relaxation process in mixtures of a nematic liquid crystal matrix with additives of azochromophores and CdSe/ZnS quantum dots is analyzed. The thermally initiated mesophase—isotropic liquid phase transition showed that the activation energy of this process increases almost equally upon the addition of AX-7 or AX-8 in an amount of 10 wt
A parametric light oscillator based on a ZGP single crystal pumped by Ho:YAG laser radiation was created, which generates radiation according to type II synchronism with smooth tuning in the spectral generation range with a width of the generated radiation of 1 cm–1 due to the use of intracavity radiation selection using a Lyot filter. The pulse energy of the generated radiation was 0.08 mJ at a pulse repetition rate of 10 kHz and a pulse duration of 26 ns. The tuning range was from 3.3 to 4.2 μm. The divergence of the generated radiation did not exceed 1.5 mrad.
Dielectric mirrors with an oxide coating for a parametric light generator based on a ZnGeP2 single crystal were fabricated. The threshold values of laser-induced breakdown of dielectric mirrors made for single-pass (no. 1) and multi-pass (no. 2) resonators (3.5 ± 0.1 and 3.9 ± 0.1 J/cm2, respectively) are determined. Based on the obtained data, the mirrors were tested in the OPO system based on the ZnGeP2 single crystal. The maximum generation efficiency achieved in the experiment was 54
Electrodynamic modeling of the interaction of microwaves with a nonlinear distributed semiconductor inclusion (a Gunn diode of planar geometry) in a strip-slot structure has been carried out by solving a nonlinear 3D diffraction problem (Maxwell's equations together with the equation of motion of charge carriers in a semiconductor) using a computational algorithm developed by the cross-sectional method. Using the method of nonlinear autonomous blocks with Floquet channels, the results of electrodynamic calculations of the amplitudes of reflected waves (at the input sections of a planar Gunn diode) of the fundamental type of the first and three higher harmonics depending on the longitudinal size of the semiconductor inclusion in the strip-slot line have been obtained.
A model including the graphene complex permittivity tensor has been developed in MWS CST and the efficiency of magnetic field tunability of metasurfaces made of graphene 1D nanoribbons has been modeled depending on the induction of the applied magnetic field and the period, size of the nanoribbons in the THz and far-infrared ranges.
The dispersions of the refractive index and absorption coefficient were determined for monolayers of titanium oxide and silicon oxide. The design of a multilayer antireflective optical coating for these materials in the spectral range of 0.4–8 μm has been developed. Modes for applying coating using ion-beam sp-uttering onto a semiconductor substrate have been selected. The optical characteristics of a four-layer interference coating with antireflection coating on a ZGP substrate were measured in the range of 2097 nm and 3.5–5 μm, with residual reflection R ≤ 0.2
The design of an interference coating made of a pair of Nb2O5/SiO2 materials on a quartz glass s-ubstrate has been simulated. A dichroic mirror has been created on the basis of the calculated design with reflection coefficients R < 1
The characteristics of a planar optical resonator made of quartz glass surrounded by silver mirrors were studied as their thickness varied. The frequency responses of bandpass filters were measured on planar structures obtained by vacuum deposition on quartz glass (SiO2) substrates of three quartz layers, which are half-wavelength resonators separated by four silver (Ag) layers from each other, from the substrate, and from free space. The thicknesses of the Ag and SiO2 layers were determined based on the specified parameters of the filter passband by synthesizing one-dimensional models using electrodynamic analysis. The experimental frequency dependences of the real and imaginary parts of the complex permittivity of silver were taken into account. The measured frequency responses of the manufactured prototypes of red, green, and purple filters are in good agreement with the characteristics obtained during synthesis. Systematic studies of filters with a central bandwidth frequency of 300 THz (wavelength of 1 µm) and a relative width of 2-20%, containing from 3 to 6 resonators, have been carried out. The high performance of the developed filters shows the prospects of their use in optical devices.
Sodium alkylbenzene sulfonates or linear alkylbenzene sulfonates (LAS), as they are commonly known, are among the most toxic anionic synthetic surfactants, which are stable in the freshwater environment. A new approach is proposed to determine these toxicants in natural water in the form of alkylbenzene sulfonic acid methyl esters using high-performance liquid chromatography (HPLC) with spectrophotometric detection in the UV spectral range. The limit of quantification (LOQ) estimated from the peak of the C10 homologue group is 16.0 ng/L under analysis on a Milikhrom™ А-02 chromatograph with a microcolumn 2 × 75 mm in size with a Nucleosil 100-5-С18 sorbent. A new method is proposed for extraction and preconcentration of linear alkylbenzene sulfonates from filtered and ethyl alcohol-preserved water samples, which includes (i) solid-phase extraction on reversed-phase C18 cartridges at a flow rate of 30–50 cm3/min (recovery 100
The aim of this paper is to provide an overview of the current state of graphene magnetoplasmonics, including fundamentals and applications. We consider the physical effects, including the “giant” Faraday effect, in electrically and magnetically controlled graphene magnetoplasmonic metasurfaces, as well as their use for creating new graphene-based plasmonic devices in the THz and IR range that are dynamically tunable by an external magnetic field. We present the principles of operating of electrically and magnetically tunable graphene THz and IR devices: THz absorbers, switches, polarizers, filters, sensors, modulators and integrated magneto-optical elements such as IR isolators and circulators. We discuss their applications in photonics and optoelectronics, telecommunications, THz spectrometry, and biomedical technologies.
As a result of the research, the model combining the ResNet-50 architecture and the pre-trained BERT language model that has achieved the following indicators: Accuracy 0.94, AUROC 0.87, and F1‑score 0.90 has been developed.
Modern robotic systems are equipped with complex electrical equipment, which accounts for more than half of the failures caused by degradation processes. Monitoring of the electrical equipment of transport mobile robotic complexes is necessary to warn of the approaching limit. The model of change of the technical condition based on fuzzy inference that allows solving monitoring tasks is discussed. The development of monitoring support based on the considered model will increase the life of transport robotic complexes.
The mesomorphic, optical, orientation, and dielectric properties of a nematic liquid crystal (LC) of 4-pentyl-cyclohexyl-4-benzonitrile (5PCH) doped with optically active (bis)camphoralidene-ethylenediamine (C2-bisCamN) have been studied. On the basis of the analysis of mesophase textures, the chiral nematic induction has been detected with the addition of dopant. The helical pith of the induced chiral nematic in mixtures has been measured by the Grandjean–Cano method and the helical twisting power has been estimated. It has been shown that the chiral induction effectiveness decreases with increasing dopant concentration because of association. The clearance temperatures of the mixtures have been measured and the degree of destabilization of the mesophase with the introduction of dopant was assessed by the method of the polarization thermomicroscopy. The effect of a chiral dopant on the mesophase anisotropic characteristics such as: dielectric permeability and birefringence, has been studied. It has been found that the introduction of C2‑bisCamN and the formation of a chiral mesophase are accompanied by a decrease in dielectric and optical anisotropy and orientational ordering. In this case, the main contribution to the change in anisotropic characteristics has been made by the helical twisting and the local orientation of the “quasi-nematic” layers. The associative state of the mesophase of the binary systems based on the strongly polar cyan derived LCs has been evaluated using the Kirkwood correlation factor. A decrease in the degree of the antiparallel dipole-dipole association of 5PCH with an increase in the concentration of the additive has been shown. The optimized structures of the monomers and dimers of 5PCH, C2-bisCamN, and solvates based on them have been obtained using quantum chemical calculations. Analysis of the geometric parameters (anisotropy of shape and molar volumes), polarity, optical activity, and the stability energies of the monomers and supermolecules has allowed us to identify camphorodiimine associates as the most likely structures responsible for the properties of the induced chiral mesophase in the 5PCH + C2-bisCamN system.
The relevance of the topic is because of the need to master the infrared (IR) range for optical telecommunications systems, IR spectroscopy and biophotonics applications and is dictated by the needs of nonlinear IR optics in the implementation of active optical functions based on graphene, such as IR radiation generation, frequency conversion for applications in optical communications, material processing, precision measurements, spectroscopic sensing, and biological sensors. The purpose of this work is to present the principles of construction and operation of electrically tunable nonlinear devices in the far- and mid-IR ranges: harmonic generators, multipliers, frequency converters, and mixers based on graphene metasurfaces, using the latest achievements of graphene plasmonics.
Observation by optical polarization microscopy of test particles (spacers) embedded in a nematic layer with negative diamagnetic susceptibility placed in a magnetic field has shown that there is no movement of particles in the realized torsion geometry. In this regard, a model of magnetohydrodynamic domains describing the motion of a nematic fluid with negative diamagnetic susceptibility in the geometry of splay distortion has been considered.
In this paper, we study the influence of multiphoton absorption on the propagation of electromagnetic waves in a nonlinear optical anisotropic medium with carbon nanotubes. The effective equation for the vector potential of the electromagnetic field of the pulse is obtained, taking into account the second component of the polarization of the field, as well as two- and three-photon absorption processes. The dependence of the components of the pulse field on the parameters of the problem is revealed. Keywords: optical anisotropy, extremely short pulse, multiphoton absorption.
The paper proposes a method for calculating the ground state of the lithium atom based on the search for the roots of the Jost function calculated for the process of electron scattering by a singly ionized ion.
