Suppression of scattering for small dielectric particles: anapole mode and invisibility

Luk’yanchuk, Boris; Paniagua‐Domínguez, Ramón; Кузнецов, А. И.; Miroshnichenko, Andrey E.; Kivshar, Yuri S.

doi:10.1098/rsta.2016.0069

Cited by 76 publications

(65 citation statements)

References 42 publications

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“…Toroidal moments are not limited to the electric type; there are few works showing the existence of the corrections to magnetic dipole (MD) moments, which can be associated with the magnetic toroidal dipoles . Thereby, the electric and magnetic toroidal moments complement the conventional electric and magnetic ones and form a full set of all possible sign permutations under the inversion of space

r \to - r

and time

t \to - t

…”

Section: Introductionmentioning

confidence: 99%

“…Now, the study of nonradiative current configurations is in its initial stage, and only electric dipole “anapole” states of different orders and magnetic “anapoles” (destructive interference of a magnetic dipole moment and a corresponding toroidal multipole) are shown. The Mie theory allows the numerous zeros of the scattering coefficients for spherical particles to be investigated, but does not allow the basic and/or toroidal contributions corresponding to different current configurations to be distinguished . Therefore, higher‐order toroidal multipoles and anapole states were neither identified nor discussed.…”

Section: Introductionmentioning

confidence: 99%

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The High‐Order Toroidal Moments and Anapole States in All‐Dielectric Photonics

Gurvitz

Ladutenko

Dergachev

et al. 2019

Laser & Photonics Reviews

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181

165

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All‐dielectric nanophotonics attracts ever increasing attention nowadays due to the possibility of controlling and configuring light scattering on high‐index semiconductor nanoparticles. It opens a room of opportunities for designing novel types of nanoscale elements and devices, and paves the way for advanced technologies of light energy manipulation. One of the exciting and promising prospects is associated with utilizing the so‐called toroidal moment, being the result of poloidal currents excitation, and anapole states, corresponding to the interference of dipole and toroidal electric moments. Here, higher‐order toroidal moments of both types (up to the electric octupole toroidal moment) are presented and investigated in detail via the direct Cartesian multipole decomposition allowing new near‐ and far‐field configurations to be obtained. Poloidal currents can be associated with vortex‐like distributions of the displacement currents inside nanoparticles, revealing the physical meaning of the high‐order toroidal moments and the convenience of the Cartesian multipoles as an auxiliary tool for analysis. High‐order nonradiating anapole states accompanied by the excitation of intense near‐fields are demonstrated. It is believed that the results are of high importance for both the fundamental understanding of light scattering by high‐index particles and a variety of nanophotonics applications and light governing on nanoscale.

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r \to - r

and time

t \to - t

…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The High‐Order Toroidal Moments and Anapole States in All‐Dielectric Photonics

Gurvitz

Ladutenko

Dergachev

et al. 2019

Laser & Photonics Reviews

Self Cite

181

165

View full text Add to dashboard Cite

show abstract

“…In contrast, all‐dielectric metamolecules and metamaterials based on them are more flexible for geometry and scale manipulations that are reasonable for optical devices. Therefore, the comparative cheapness and variety of materials constantly expand the use of all‐dielectric metamaterials in nanophotonics …”

Section: Introductionmentioning

confidence: 99%

Toroidal Dipole Mode Observation In Situ

Pavlov

Stenishchev

Ospanova

et al. 2019

Physica Status Solidi (b)

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Besides classical dipole moments, the metaparticles are characterized by toroidal dipole moments that are important for numerous applications ranging from strong field localizations to anapole modes and the dynamic Aharonov–Bohm effect. On the other hand, the toroidal and electric dipole radiation are undistinguished by external observers due to identical radiation patterns. Therefore, the importance of toroidal dipole moments in multipole expansion is questioned by many researchers. However, a long‐awaited unanswered question is—what is going on inside a toroidal metamolecule and is its near‐field distribution distinct from the electric dipole field? Herein, the toroidal dipole mode is experimentally confirmed in situ by proof‐of‐concept measurements of electric and magnetic fields inside properly fabricated water metamolecules with toroidal topology in the microwave frequency range.

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“…However, we would like to note that the electric quadrupole contribution could be suppressed by increasing the refractive index of the particle [28,33]. Finally, although we consider here dispersionless particles, we expect that TM FD pulses can still excite anapole modes in particles with weak dispersion.…”

Section: Fig 1: Schematic Illustrating a Transverse Magnetic (Tm)mentioning

confidence: 99%

Exciting dynamic anapoles with electromagnetic doughnut pulses

Raybould

Fedotov

Papasimakis

et al. 2017

Applied Physics Letters

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As was predicted in 1995 by Afanasiev and Stepanofsky, a superposition of electric and toroidal dipoles can lead to a non-trivial non-radiating charge current-configuration, the dynamic anapole. The anapoles were recently observed first in microwave metamaterials and then in dielectric nanodisks. However, spectroscopic studies of toroidal dipole and anapole excitations are challenging owing to their diminishing coupling to transverse electromagnetic waves. Here, we show that anapoles can be excited by electromagnetic Flying Doughnut (FD) pulses. First described by Helwarth and Nouchi in 1996, FD pulses are space-time inseparable exact solutions to Maxwells equations that have toroidal topology and propagate in free-space at the speed of light. We argue that FD pulses can be used as a diagnostic and spectroscopic tool for the anapole excitations in matter.Flying Doughnut (FD) pulses were introduced by Hellwarth and Nouchi in 1996 [1] as exact solutions to Maxwells equations in free-space [2][3][4][5][6][7][8][9]. They are necessarily few-cycle, wideband electromagnetic perturbations with toroidal field topology that can exist in transverse electric (TE) and transverse magnetic (TM) configurations [1,10]. FD pulses can be seen as propagating counterparts of the localized toroidal dipole excitations in matter [11]. The toroidal dipole is distinct from the conventional electric and magnetic dipoles [12,13] and have attracted significant interest in recent years as important contributors to the electromagnetic properties of media with non-local response or elements of toroidal symmetry [11,[14][15][16][17][18][19][20][21]. Superposition of dynamic electric and toroidal dipoles leads to anapoles which, through destructive interference, exhibit vanishing radiated fields outside the source [20,22]. Anapoles have been observed in microwave metamaterials [16] and dielectric nanoparticles [18], and their excitation has also been predicted in core-shell nanoparticles [23] and nanowires [24]. Moreover, anapoles have been employed to enhance nonlinear effects [25] and realize high-Q microwave metamaterials [26]. However, anapole modes are weakly coupled to freespace radiation, which renders experimental observations particularly challenging. In this paper, we demonstrate numerically the excitation of anapoles in a spherical dielectric particle driven by an FD pulse.We consider a dispersionless spherical dielectric particle interacting with a TM FD pulse, as depicted in Fig. 1. The FD pulse is brought to focus on the dielectric sphere located at the origin of the coordinate system. The interactions between FD pulses and dielectric spherical particles are investigated by a finite element solver of Maxwell's equations in three dimensions. The simulations are conducted in the transient domain. We define the incident FD pulse as per the field prescriptions in ref. (1)where σ = z + ct and τ = z − ct, and f 0 is an arbitrary normalisation constant. The parameters q 1 and q 2 have dimensions of length and represent respectively the ...

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Suppression of scattering for small dielectric particles: anapole mode and invisibility

Cited by 76 publications

References 42 publications

The High‐Order Toroidal Moments and Anapole States in All‐Dielectric Photonics

The High‐Order Toroidal Moments and Anapole States in All‐Dielectric Photonics

Toroidal Dipole Mode Observation In Situ

Exciting dynamic anapoles with electromagnetic doughnut pulses

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