Vol 87, No 12 (2023)

A method for implementing sectoral diffractive optical elements formed from phase distributions of simple optical elements is presented. The capture and rotation of latex microparticles with a diameter of 3–4 μm in optothermal traps using formed elements has been demonstrated.

The problem of high-performance systems for the big data transmission and processing fabrication determines the importance of creating hybrid photonic integrated circuits with complex architecture. We studied of three-dimensional photonic waveguide structures created by direct (3 + 1)D laser writing, with the aim of adding such structures to photonic integrated circuits.

We studied the reflective properties of an active periodic medium with quadratic nonlinearity using numerical modeling based on the description of the generation of the second optical harmonic in the quasi-optical approximation. The model under consideration appears to be a system of four coupled equations for slowly varying amplitudes of forward and backward waves. Based on numerical simulation, the influence of the asymmetric Bragg coupling of counterpropagating waves at the fundamental frequency on the absorbing/generating and reflecting properties of the active medium is analyzed.

An abrupt lengthening (from 295 to 684 μs) of the luminescence decay time of Tb³⁺ ions in a solution of a terbium(III) complex with tetra-1,3-diketone calix[4]arene in the region of the solution crystallization temperature (212 K) was found. This fact indicates a significant sensitivity of the complex to the structure of the local environment, which can be used both for spectroscopic purposes and for remote monitoring of the phase state of the medium.

The results of temperature testing of the two-phosphor composite ([Ru(dipy)₃]²⁺@SiO₂ and NaYF₄:Eu,Gd) are presented in order to assess the prospects for its further application as a luminescent thermal sensor in the range of 200–310 K. By calibrating the temperature dependences of individual spectral components of the emission produced under irradiation by cw laser at 405 nm, the possibilities of temperature sensing by means of ratiometric method are analyzed in four different spectral ranges of the composite’s visible luminescence.

The upconversion NaYbF₄:Er nanorods were synthesized by the hydrothermal method at the temperature of 190°C for 24 h. The luminescence spectrum exhibits intense luminescence lines in the visible and near-IR ranges under 977 nm laser diode excitation. The polarization of the upconversion luminescence of a large ensemble of nanoparticles is isotropic. Considering the pronounced rod structure of nanoparticles, the presence of several subensembles with different polarization characteristics of the luminescence was assumed.

Based on the spatial distribution of the electric field strength of diffraction-free extremely short Bessel and Airy–Bessel optical pulses, patterns of the temporal evolution of the current density in a nonlinear array of semiconductor carbon nanotubes with a spatial modulation of the refractive index are constructed. The dependences of the maximum value of the current density on the modulation parameters of the refractive index of the medium are established.

We simulated the propagation of a quasi-monochromatic laser beam in a medium with carbon nanotubes. Equations describing the dynamics of laser beams in an array of carbon nanotubes are obtained based on the hydrodynamic approach for the nonlinear Schrödinger equation. This equation is solved numerically using the smoothed particle method. The evolution of the beam is analyzed depending on the frequency of the electric field.

Studies of magnetically dependent effects of nonresonant absorption of electromagnetic wave energy in the resonator of the X-band EPR spectrometer related to the superconductivity of metallic lead inclusions and microscopic structural defects in crystals of narrow-band semiconductors PbS_{1 – x} and PbS_{1 – x}:Mn have been performed. It is shown that nanoscale lead particles present in polycrystalline material PbS_0.96 with a high content of sulfur vacancies at temperatures of 2.6–8 K manifest themselves as superconductors of the 2nd kind and demonstrate high thermomagnetic stability. It was found that in a single-crystal sample PbS_0.996 with a significantly lower concentration of sulfur vacancies under the influence of the electric component of the microwave field in the resonator of the ESR spectrometer, non-periodic bursts of microwave power absorption associated with avalanches of Abrikosov vortices and demonstrating the absence of thermomagnetic stability of superconducting regions associated with defects in the crystal structure of the sample PbS_0.996 are observed.

Optical heating in solids is fundamentally related to energy dissipation during absorption. Nevertheless, light absorption can be enhanced by excitation of optical resonances (plasmon, Mi, Fano, etc.). In this paper, we investigate the amplification of light absorption in nanostructured silicon by excitation of an optical near field in the gap between the tip of a silicon probe and a gold film.

The local molecular dynamics and the free volume distribution in the blend of polyvinyl chloride and polyvinyl butyral in the ratio 1 : 1 were studied by FTIR spectroscopy. The freezing temperatures of the conformational equilibria of five conformationally inhomogeneous compounds in the blend under study were determined, and the effective sizes of the mobile free volume elements in the blend were determined.

A method for synthesizing a magnetic fluid with ferromagnetic nanowires based on silicone oil is described, and a magnetorheological effect is demonstrated. The physical characteristics of the resulting ferrophase were studied using optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray phase analysis. The size of the nanowires was measured by dynamic light scattering, for which the conditions for stabilizing ferromagnetic wires in an aqueous solution by coating with polyvinylpyrrolidone were selected.

The features of the developed complex remote method for diagnosing the current operating condition and predicting the residual life of high-voltage insulators under operating conditions are considered. The basis is the registration and subsequent computer analysis of a set of experimentally established diagnostic parameters of partial discharges. To find and localize the location, type and degree of danger of defects, a two-channel contactless method of registering partial discharges using electromagnetic and acoustic sensors as part of narrow-focused antennas is used. Special attention is paid in the article to the influence of the most dangerous defects arising due to induced electric fields created by previous partial discharges.