Toroidal multipoles are the terms missing in standard multipole expansion; they usually overlooked due to their relatively weak coupling electromagnetic fields. Here we propose and theoretically study all-dielectric metamaterials of a special class that represent simple system supporting toroidal dipolar excitations THz part spectrum. We show resonant transmission reflection such is dominated by dipole scattering, neglect which would result misunderstanding interpretation macroscopic...

We have designed and fabricated a metamaterial consisting of planar metamolecules which exhibit unusual, almost perfect anapole behavior in the sense that electric dipole radiation is canceled by toroidal one, producing thus an extremely high $Q$-factor at resonance frequency. Thus we demonstrated theoretically experimentally metamaterials approaching ideal very $Q$-factor. The size system, millimeter range, parasitic magnetic quadrupole are factors limiting In spite low losses estimated...

Abstract This paper is dedicated to a type of perforated silicon metamaterials, possessing anapole mode in visible spectral range due destructive interference between electric and toroidal dipole moments. The proposed structure gains both attainable material simplified fabrication. Such exhibits desirable physical effect has obvious practical application: it supports the without complicated 3D geometry can be processed one step by nanofabrication methods. metamaterial paves way for advanced...

Abstract We experimentally demonstrate for the first time toroidal dipolar response in metamaterials based on clusters of cylindrical dielectric particles microwave frequency range. Instead expensive ceramic elements we used distilled water with permittivity at room temperature is about 75, while loss tangent not large frequencies up to 4 GHz. Moreover, show all-dielectric metamaterial consisting box hollow tubes which more practical future applications. Our findings also that proposed ideas...

Abstract Dynamic anapole is a promising element for future nonradiating devices, such as cloaked sources and sensors, quantum emitters, especially the observing dynamic Aharonov-Bohm effect. However, response can be damped by Joule losses. In this paper we theoretically propose experimentally demonstrate novel type of active all-dielectric source, which in some sense, realizes elementary Afanasiev, study its radiative/nonradiative regimes microwave range.

In this paper, we demonstrate the relation between cloaking effect and its nonradiating state by considering destructive multipolar interaction near-field scattering bare object surrounding coating located in proximity. This is underpinned anapole mode excitation it occurs as interference electric dipole moment, generated a (here central metallic scatterer) toroidal formed inside cloak (a cluster of dielectric cylinders). Numerical results show how based on formation can lead to an overall...

We introduce a general concept and consider characteristic approach to obtain the narrow-band suppression of total electromagnetic scattering independent irradiation conditions for compound dielectric structures supporting unique anapole states. To emphasize this independence from conditions, we call selective superinvisibility effect. show that realization allows us reach simultaneously several goals significantly suppress (at certain wavelength); provide any polarization direction...

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

Numerous exciting optical effects in all-dielectric high-refractive-index structures are associated with so-called toroidal electrodynamics. Among these anapoles, nonradiated states caused by interference phenomena, e.g. between electric dipole and modes. For a spherical particle it is possible to reach simultaneous destructive for electric, magnetic, corresponding modes (so-called hybrid anapole mode), varying the refractive index and/or size. However, there no sufficient degrees of freedom...

Kerker effect is one of the unique phenomena in modern electrodynamics. Due to overlapping electric and magnetic dipole moments, all-dielectric particles can be invisible forward or backward directions. In our paper we propose new conditions between resonantly excited quadrupole ceramic high index spheroidal for demonstrating transverse effect. Moreover, perform proof-of-concept microwave experiment demonstrate dumbbell radiation pattern with suppressed scattering both directions enhanced...

Multipole decomposition method is a promising tool for investigation of radiating or scattering responses electromagnetic sources particles. It works even in the case relatively complicated and compound scatterers like multilayer particles, clusters, asymmetrical systems. Commonly, radiation fields point electric magnetic are decomposed only into dipole moments, while real can be described by series multipoles, including higher multipoles toroidal moments. In this paper, we introduce concept...

We present and analyze unique phenomena of enhanced transmission through systems subwavelength dielectric cylinders embedded in an epsilon near zero host. Our analysis shows that these are due to Mie-resonance modes arisen the cylinders. Subwavelength waveguides lenses proposed based on coupling between neighboring Finally, their possible applications numerically demonstrated THz regime a realistic polaritonic material LiF rods KCl.

We propose a model of tunable THz metamaterials. The main advantage is the blueshift resonance and phase tunability due to toroidal excitation in planar metallic metamolecules with incorporated silicon inductive inclusions.

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

We present and analyze the unique phenomena of enhanced THz transmission through a subwavelength LiF dielectric rod lattice embedded in an epsilon-near-zero KCl host. Our experimental results combination with theoretical calculations show that waveguiding terahertz radiation is achieved within alkali-halide eutectic metamaterial as result coupling Mie-resonance modes arising lattice.

We present the numerical, theoretical, and experimental study of a terahertz metasurface supporting pseudo-anapole. Pseudo-anapole effect arises when electric toroidal dipole moments both tend to minimum, instead destructive interference between in conventional anapole mode. Such overlap allows resonance suppression type radiation. Thus it becomes possible multipoles other families higher order excitations. estimate multipole contribution response via expansion method. The series is extended...

We present the experimental observation of electromagnetic mutual coupling in an array ring-shaped resonators (meta-atoms) fabricated on a free-standing thin metal film using maskless direct laser ablation technique. The transmission spectra various resonator configurations were measured via terahertz time-domain spectroscopy and vector network analysis. Numerical modeling periodically arranged resonators, employing multipole decomposition, revealed clear dependence inter-element number...

Achieving high-Q resonances in photonics is crucial for devices such as sensors, filters, and emitters of electromagnetic radiation. One effective strategy achieving involves the bound state continuum effect (BIC). In this paper, we demonstrate a comprehensive study BIC complementary planar Babinet metamaterials microwave regime. A symmetry-protected has been induced metamaterial due to rotation an incident wave small angles from normal incidence, thus releasing high Q-factor (9.245 · 103...

We have demonstrated that a dielectric plane ring with high permittivity excited by an incident electromagnetic wave in the GHz frequency range is almost ideal magnetic dipole for basic resonance of radiation scattering. The scattering fraction all other multipoles insignificant and less than 2 × 10−3 main resonance. Experimentally measured field distributions near are consistent results computer simulation Biot–Savart–Laplace law. Thus, law can be applied both to calculate conductive...

In this work, we first derive the nonradiating anapole condition with a straightforward theoretical demonstration exploiting one of Devaney-Wolf theorems for currents. Based on equivalent volumetric and surface electromagnetic sources, it is possible to establish unique compact conditions directly from Maxwell's Equations in order ensure state. addition, support our findings numerical investigation broken-symmetry dielectric particle, building block metamaterial structure, demonstrating...

Here we propose, to the best of our knowledge, a novel transparency effect in cylindrical all-dielectric metamaterials. We show that cancellation multipole moments same kind leads almost zero radiation losses metamaterials due counter-directed multipolar metamolecule. The nullifying multipoles, mainly dipoles, and suppression higher results ideal transmission an incident wave through designed metamaterial. observed could pave road new generation light-manipulating transparent metadevices...

In this paper we demonstrate the possibility of backward radiation from a negative permittivity planar (slab) waveguide. Furthermore, show that can be used to achieve sub-wavelength imaging point source placed close such slab or periodic layered system slabs. Finally, backward-radiation-based in case realistic materials operating THz regime, as polaritonic alkali-halide systems.

Black silicon (bSi) is a highly absorptive material in the UV-vis and NIR spectral range. Photon trapping ability makes noble metal plated bSi attractive for fabrication of surface enhanced Raman spectroscopy (SERS) substrates. By using cost-effective room temperature reactive ion etching method, we designed fabricated profile, which provides maximum signal enhancement under excitation when nanometrically-thin gold layer deposited. The proposed substrates are reliable, uniform, low cost...

The idea to inverse the radiation pattern of microwave antenna due appli- cation isotropic metamaterial screen with negative refractive index in S band is demon- strated at flrst time this investigation. electromagnetic simulation waveguide patterns by moment's methods demonstrates an agreement modeling measured diagrams for values efiective parameters (permittivity and permeability) extracted from S-parameters sheet sample.