Browsing by Author "Belov, Pavel"
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Item Analytical modelling of metamaterials and a new principle of sub-wavelength imaging(Helsinki University of Technology, 2006-11-22) Belov, Pavel; Department of Electrical and Communications Engineering; Sähkö- ja tietoliikennetekniikan osasto; Radio Laboratory; RadiolaboratorioThe thesis is devoted to an analytical modeling of metamaterials, artificial media with electromagnetic properties not available among natural materials. The development of metamaterials is a new branch of research in the multidisciplinary field of material physics, electromagnetics, optics, radio engineering, and electronics. The metamaterials will play a key role in providing new functionalities and enhancements to the future electronic devices and components, since it will be possible to create materials with fundamentally new properties required by new technologies. The thesis consists of comprehensive historical overview about various kinds of the metamaterials including artificial dielectrics and magnetics, bianisotropic media, double-negative materials, photonic and electromagnetic crystals, high impedance surfaces, etc., and two logically separated parts representing a summary of original results of the author on analytical modeling of some of these metamaterials and sub-wavelength imaging using canalization regime, respectively. In the analytical modeling part, the metamaterials with various inner geometries have been studied using the local field approach. This approach allows to reduce complicated eigenmode and reflection\transmission problems for periodical structures of complex inclusions to rigorously analytically solvable problems for arrays of elementary scatterers (electrical or/and magnetic dipoles, linear currents) with certain polarizability with respect to the local (acting) field. In the last part of the thesis, an original opportunity of imaging with sub-wavelength resolution by flat slabs of the metamaterials is proposed. This regime (which is called as canalization) does not involve negative refraction and amplification of evanescent modes in contrast to the case of perfect lenses formed by double-negative media. The sub-wavelength image happens to be transmitted from one interface to another one by propagating modes of the metamaterial. The canalization of images with sub-wavelength resolution may be used in medical and microwave imaging, near field microscopy and it may allow to design optical storages (DVD) with significantly improved capacity.Item Analytical studies of complex microwave stop band structures(2004) Belov, Pavel; Sihvola, Ari; Sähkö- ja tietoliikennetekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Tretyakov, SergeiItem Demonstration of the enhanced Purcell factor in all-dielectric structures(2016-05-23) Krasnok, Alexander; Glybovski, Stanislav; Petrov, Mihail; Makarov, Sergey; Savelev, Roman; Belov, Pavel; Simovski, Konstantin; Kivshar, Yuri; Department of Radio Science and Engineering; Kostantin Simovski Group; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO); Australian National UniversityThe Purcell effect is usually described as a modification of the spontaneous decay rate in the presence of a resonator. In plasmonics, this effect is commonly associated with a large local-field enhancement in "hot spots" due to the excitation of surface plasmons. However, high-index dielectric nanostructures, which become the basis of all-dielectric nanophotonics, cannot provide high values of the local-field enhancement due to larger radiation losses. Here, we demonstrate how to achieve a strong Purcell effect in all-dielectric nanostructures, and show theoretically that the Purcell factor can be increased by two orders of magnitude in a finite chain of silicon nanoparticles. Using the eigenmode analysis for an infinite chain, we demonstrate that the high Purcell factor regime is associated with a Van Hove singularity. We perform a proof-of-concept experiment for microwave frequencies and observe the 65-fold enhancement of the Purcell factor in a chain of 10 dielectric particles.Item Metasurface for Near-Field Wireless Power Transfer with Reduced Electric Field Leakage(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2020-01-01) Markvart, Aleksandr; Song, Mingzhao; Glybovski, Stanislav; Belov, Pavel; Simovski, Constantin; Kapitanova, Polina; Department of Electronics and Nanoengineering; Kostantin Simovski Group; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO)Wireless power transfer is a breakthrough technology which can be used in all aspects of humans daily life. Here, a bi-layer metasurface as a transmitter for near-field wireless power transfer is proposed and studied. The novelty and advantage of the proposed metasurface is the spatial separation of the electric and magnetic near fields. Magnetic fields responsible for power transfer are sufficiently high on top of the metasurface whereas the electric fields are almost completely confined between two layers of the metasurface. These unique properties have been obtained due to the special metasurface design based on two orthogonal layers of resonant wires immersed in high-permittivity background. The theoretical and experimental study reveal the quasi-uniform magnetic field distribution over the metasurface dimensions of $40\times 40$ cm2 that makes it suitable for wireless power transfer via resonant magnetic coupling to one or several receivers placed above it. Compared with a conventional planar spiral coil solution, the specific absorption rate of the proposed metasurface is reduced by 47 times, which enables to greatly increase the allowable transferred power without violating the safety regulation and reducing the efficiency.Item Microwave reflecting focusing metasurface based on water(2018) Odit, Mikhail; Sayanskiy, Andrey; Asadchy, Viktar; Belov, Pavel; Department of Electronics and Nanoengineering; Sergei Tretiakov Group; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO)In this work we demonstrate the first design of the focusing reflecting all-dielectric metasurface which is realized on periodically arranged bianisotropic elements made of distilled water. The metasurface was shown to demonstrate focusing capabilities of the reflected electromagnetic signal at 12 GHz while preserving transparency outside of the operating frequency band.Item Mushroom High-Impedance Metasurfaces for Perfect Absorption at Two Angles of Incidence(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017-08-05) Zhirihin, Dmitry; Simovski, Constantin; Belov, Pavel; Glybovski, Stanislav; Department of Electronics and Nanoengineering; Kostantin Simovski Group; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO)In this letter, we study the possibility to achieve perfect absorption of TM-polarized plane electromagnetic waves for two incidence angles at the same frequency. The effect was obtained in a high-impedance surface (HIS) also called a mushroom metasurface due to a combination of two types of dissipation losses inside each unit cell of the HIS, dielectric losses, and resistance of lumped loads. The dual-angle perfect absorption is a narrowband resonance effect. It was shown analytically that one can completely suppress the reflection at two predefined angles of incidence. This result was confirmed by numerical simulations of a practical (realistic and affordable) structure.Item Smart Table Based on a Metasurface for Wireless Power Transfer(American Physical Society, 2019-05-16) Song, Mingzhao; Baryshnikova, Kseniia; Markvart, Aleksandr; Belov, Pavel; Nenasheva, Elizaveta; Simovski, Constantin; Kapitanova, Polina; Department of Electronics and Nanoengineering; Kostantin Simovski Group; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO); Ceramics Co. LtdWe propose the concept of and experimentally demonstrate a metasurface-based smart table for wireless power transfer. The proposed structure supports propagating surface modes that can be excited by the near field of wireless devices. As a result, if two devices are placed anywhere on a metasurface table, a substantial enhancement of the effective near-field coupling can be achieved. This enhancement leads to a demonstrated power-transfer efficiency of 80% for the receiver placed in any location with respect to the transmitter on the table. The proposed concept enables a variety of applications from consumer electronics to charging electric cars.Item Wire metamaterial filled metallic resonators(American Physical Society, 2022-08-15) Balafendiev, Rustam; Simovski, Constantin; Millar, Alexander J.; Belov, Pavel; Department of Electronics and Nanoengineering; Kostantin Simovski Group; Stockholm University; St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO)In this work we study electromagnetic properties of a resonator recently suggested for the search of axions - a hypothetical candidate to explain dark matter. A wire medium loaded resonator (called a plasma haloscope when used to search for dark matter) consists of a box filled with a dense array of parallel wires electrically connected to top and bottom walls. We show that the homogenization model of a wire medium works for this resonator without mesoscopic corrections, and that the resonator quality factor Q at the frequency of our interest drops versus the growth of the resonator volume V until it is dominated by resistive losses in the wires. We find that even at room temperature metals like copper can give quality factors in the thousands - an order of magnitude higher than originally assumed. Our theoretical results for both loaded and unloaded resonator quality factors were confirmed by building an experimental prototype. We discuss ways to further improve wire medium loaded resonators.
