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Alexey A. Basharin

Publications and source records attributed to Alexey A. Basharin.

12 recordsLinked to original sources
arXiv2024

Active Control of Bound States in the Continuum in Toroidal Metasurfaces

The remarkable properties of toroidal metasurfaces, featuring ultrahigh-Q bound states in the continuum (BIC) resonances and nonradiating anapole modes, have garnered significant attention. The active manipulation of quasi-BIC resonance characteristics offers substantial potential for advancing tunable metasurfaces. Our study explores explicitly the application of vanadium dioxide, a phase change material widely used in active photonics and room-temperature bolometric detectors, to control quasi-BIC resonances in toroidal metasurfaces. The phase change transition of vanadium dioxide occurs in a narrow temperature range, providing a large variation in material resistivity. Through heating thin film patches of vanadium dioxide integrated into a metasurface comprising gold split-ring resonators on a sapphire substrate, we achieve remarkable control over the amplitude and frequency of quasi-BIC resonances due to their high sensitivity to losses present in the system. Breaking the symmetry of meta-atoms reveals enhanced tunability. The predicted maximum change in the quasi-BIC resonance amplitude reaches 14 dB with a temperature variation of approximately 10 °C.

physics.optics↗
arXiv2018

Equivalent sources approach for non radiating states and anapole metamaterials

In this work, we discuss theoretical findings on the common feature describing nonradiating sources, based on equivalent sources from which it is possible to derive cloaking devices and anapole mode conditions. Starting from the differential form of Maxwell's Equations expressed in terms of equivalent electromagnetic sources, we derive two unique compact conditions. By specifying the nature of these passively induced or actively impressed current density sources in certain volumes and (or) predefined surfaces, we derive theoretical results consistently with the literature about nonradiating particles, cloaking devices and anapole mode structures through peculiar destructive interactions between volumetric-volumetric, volumetric-surface and surface-surface equivalent sources.

physics.optics↗
arXiv2018

Electromagnetic sources beyond common multipoles

The complete dynamic multipole expansion of electromagnetic sources contains more types of multipole terms than it is conventionally perceived. The toroidal multipoles are one of the examples of such contributions that have been widely studied in recent years. Here we inspect more closely the other type of commonly overlooked terms known as the mean-square radii. In particular, we discuss both quantitative and qualitative aspects of the mean-square radii and provide a general geometrical framework for their visualization. We also consider the role of the mean-square radii in expanding the family of non-trivial non-radiating electromagnetic sources.

physics.class-ph↗
arXiv2018

Anapole mode excitation in novel perforated all-dielectric metamaterials

In this paper, we concern on nonradiating properties of novel silicon metamaterials due to multipolar interaction. Destructive interference of electric dipole moment and the next term of multipolar decomposition - toroidal dipole moment, leads to nonradiating anapole mode, which is nowadays widely studying among electrodynamic phenomena. Therefore, we propose technically simple metamaterial design, which does not demand multistep fabrication. This kind of metamaterial is the promising in nanophotonics and plasmonics due to subtle sensing, nonradiative data transfer, Aharonov-Bohm effect and other demonstrations.

physics.app-ph↗
arXiv2017

Electromagnetically Induced Transparency in all-dielectric metamaterials due to nullifying of multipole moments

Here, we propose novel transparency effect in cylindrical all-dielectric metamaterials. We show that cancellation of multipole moments of the same kind lead to almost zero radiation losses due to the counter-directed multipolar moments in metamolecule. . Nullifying of multipoles, mainly dipoles and suppression of higher multipoles results in ideal transmission of incident wave through the designed metamaterial. The observed effect could pave the road to new generation of light-manipulating transparent metadevices such as filters, waveguides, cloaks and more.

physics.app-ph↗
arXiv2017

Non-radiating sources, dynamic anapole and Aharonov-Bohm effect

We show that for a particular choice of gauge the vector potential of any non-radiating source is spatially localized along with its electric and magnetic fields. Important on its own, this special property of non-radiating sources dramatically simplifies the analysis of their quantitative aspects, and enables the interpretation of non-radiating sources as distributions of the elementary dynamic anapoles. Using the developed approach we identify and discuss a possible scenario for observing the time-dependent version of the Aharonov-Bohm effect in such systems.

physics.optics↗
arXiv2016

Extremely High Q-factor metamaterials due to Anapole Excitation

We demonstrate that ideal anapole metamaterials have infinite Q-factor. We have designed and fabricated a metamaterial consisting of planar metamolecules which exhibit anapole behavior in the sense that the electric dipole radiation is almost cancelled by the toroidal dipole one, producing thus an extremely high Q-factor at the resonance frequency. The size of the system, at the mm range, and the parasitic magnetic quadrupole radiation are the factors limiting the size of the Q-factor. In spite of the very low radiation losses the local fields at the metamolecules are extremely high, of the order of higher than the external incoming field.

physics.class-ph↗
arXiv2016

Extremely high Q-factor toroidal metamaterials

We demonstrate that, owing to the unique topology of the toroidal dipolar mode, its electric/magnetic field can be spatially confined within subwavelength, externally accessible regions of the metamolecules, which makes the toroidal planar metamaterials a viable platform for high Q-factor resonators due to interfering toroidal and other dipolar modes in metamolecules.

physics.class-ph↗
arXiv2014

Dielectric Metamaterials with Toroidal Dipolar Response

Toroidal multipoles are the terms missing in the standard multipole expansion; they are usually overlooked due to their relatively weak coupling to the electromagnetic fields. Here we propose and theoretically study all-dielectric metamaterials of a special class that represent a simple electromagnetic system supporting toroidal dipolar excitations in the THz part of the spectrum. We show that resonant transmission and reflection of such metamaterials is dominated by toroidal dipole scattering, the neglect of which would result in a misunderstanding interpretation of the metamaterials macroscopic response. Due to the unique field configuration of the toroidal mode the proposed metamaterials could serve as a platform for sensing, or enhancement of light absorption and optical nonlinearities.

physics.optics↗
arXiv2014

Dielectric rod feed for compact range reflector

A dielectric rod feed with a special radiation pattern of a tabletop form used for the compact range reflector is developed and analyzed. Application of this feed increases the size of the compact range quiet zone generated by the reflector. The feed consists of the dielectric rod made of polystyren, the rod is inserted into the circular waveguide with a corrugated flange. The waveguide is excited by the H11-mode. The rod is covered by the textolite biconical bushing and has a fluoroplastic insert in the vicinity of the bushing. Mathematical modeling was used to obtain the parameters of the feed for the optimal tabletop form of the radiation pattern. The problem of the electromagnetic radiation was solved for metal-dielectric bodies of rotation by method of integral equations with further solving of the problem of the synthesis for feed parameters. The dielectric rod feed was fabricated for the X-frequency range. Feed amplitude and phase patterns were measured in the frequency range 8.2-12.5 GHz. Presented results of mathematical modeling and measurements for X-range radiation patterns correlate well. It is shown that this feed increases by 20-25% the quiet zone of the compact range with reflector in the form of nonsymmetrical cutting of the paraboloid of revolution 5.0 x 4.5 m in size in the frequency range 8.5-10.0 GHz as compared to a conical horn feed.

physics.ins-det↗
arXiv2013

Toroidal Response in Dielectric Metamaterials

We present and analyze a dielectric cluster based on subwavelength LiTaO3 polaritonic cylinders for demonstrating toroidal response in THz regime due to mutual coupling of Mie- resonance modes of the cylinders. Based on this cluster, we demonstrate a low-loss metamaterial with the dominant toroidal response, which plays a key role in achieving resonant total transmission.

physics.optics↗