Electromagnetic sources beyond common multipoles

Nemkov, Nikita; Basharin, Alexey A.; Fedotov, V.A.

doi:10.1103/physreva.98.023858

Cited by 40 publications

(35 citation statements)

References 22 publications

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“…They can be deduced in a similar manner to the fundamental anapole condition but by involving higher‐order terms in the multipole expansion. The different multipolar terms can have the same far‐field radiation pattern, though their relative contributions scale differently as the wavelength changes . In particular, the lowest‐order magnetic nonradiating source is formed by a magnetic dipole and its first mean‐square radius (see Table ), while toroidal multipoles can interfere with their own mean‐square radii, leading to the anapole state formation even in the absence of electric multipoles.…”

Section: Anapole Concept In Metaopticsmentioning

confidence: 99%

Optical Anapoles: Concepts and Applications

Baryshnikova

Smirnova

Luk’yanchuk

et al. 2019

Advanced Optical Materials

227

177

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Interference of electromagnetic modes supported by subwavelength photonic structures is one of the key concepts that underpins the nanoscale control of light in metaoptics. It drives the whole realm of all‐dielectric Mie‐resonant nanophotonics with many applications for low‐loss nanoscale optical antennas, metasurfaces, and metadevices. Specifically, interference of the electric and toroidal dipole moments results in a very peculiar, low‐radiating optical state associated with the concept of optical anapole. Here, the physics of multimode interferences and multipolar interplay in nanostructures is uncovered with an intriguing example of the optical anapole. The recently emerged field of anapole electrodynamics is reviewed, explicating its relevance to multipolar nanophotonics, including direct experimental observations, manifestations in nonlinear optics, and rapidly expanding applications in nanoantennas, active photonics, and metamaterials.

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Section: Anapole Concept In Metaopticsmentioning

confidence: 99%

Optical Anapoles: Concepts and Applications

Baryshnikova

Smirnova

Luk’yanchuk

et al. 2019

Advanced Optical Materials

227

177

View full text Add to dashboard Cite

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“…Hence, under illumination with an incident light, each term in a dynamic mode decomposition supports only a specific angular projection of the charge-current distribution. Moreover, in the context of mean-square radii, one can easily explore its 1st order of an electric or a magnetic dipole, as demonstrated previously in Nemkov et al [22]. By centering on the super-toroidal modes from the quantitative perspective, we first study the hierarchy of a toroidal solenoid system, in which each turn of it can be considered as another toroidal solenoid.…”

Section: The Theory Of High-order Toroidal Solenoidsmentioning

confidence: 99%

“…Nevertheless, they have a key role in the field of nanophotonics and plasmonics [4]. As indicated by Nemkov et al [22], the decomposition scheme generates high-order modes within the hierarchy of a toroidal system (i.e., toroidal solenoid), known as "mean-square radii" of the induced toroidal mode. It is noteworthy to mention that without complementing the multipole expansion with these high-order terms, the decomposition will be incorrect [23].…”

Section: The Theory Of High-order Toroidal Solenoidsmentioning

confidence: 99%

The Observation of High-Order Charge–Current Configurations in Plasmonic Meta-Atoms: A Numerical Approach

Gerislioglu

Ahmadivand

2019

Photonics

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Living in a world of resonances, there have been significant progresses in the field of excitation of pronounced and multifunctional moments across a wide range of optical frequencies. Among all acknowledged resonances, the toroidal multipoles have received copious interest in recent years due to possessing inherent signatures in nature. As a fundamental member, toroidal dipole is a strongly localized electromagnetic excitation based on charge–current configurations, which can be squeezed into an extremely small spot. Although there have been extensive studies on the behavior and properties of toroidal dipoles in order to develop all-optical devices based on this technology, so far, all analyses are restricted to the first (1st) order toroidal dipoles. In this work, using a practical technique, we successfully observed exquisite multi-loop super-toroidal (MLST) spectral features in a planar multipixel metallodielectric meta-atom. Employing the theory behind the excitation of multi-loop currents, we numerically and theoretically demonstrated that a traditional toroidal dipole can be transformed into a super-toroidal moment by varying the dielectric permittivity of the capacitive gaps between proximal pixels. This understanding introduces a new approach for the excitation of complex multi-loop toroidal moments in plasmonic metamaterials with high sensitivity, applicable for various nanophotonics applications from sensing to filtering.

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“…Based on this destructive interference, anapoles generated from high-order multipoles (electric, magnetic, and toroidal) have been studied theoretically [10]. Furthermore, it is possible to create from a single multipolar current-charge distribution other high-order multipolar sources that are denominated moments of mean-square radii (MSRs) [11]; peculiarly, the radiation pattern of a MSR source is the same as that of its parent multipole and hence the superposition of these sources gives rise to an anapole.…”

Section: Introductionmentioning

confidence: 99%

Anapole arising from a Mie scatterer with dipole excitation

Zurita-Sánchez

2019

Phys. Rev. Research

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We examine theoretically that an electric dipole close to a subwavelength sphere can yield an anapole (the dipole-sphere system is a nonradiating source). Physically, the anapole arises when the dipole induced by the source inside the sphere cancels out with the dipole contribution of the source with respect to the center of the sphere. The condition for the anapole is established and this state can be achieved with either a dielectric sphere with a high refractive index or a metallic sphere. Since there is a residual radiation (much smaller than the radiated power of the dipole in the absence of the scatterer) originating from high-order multipoles, the anapole is almost ideal. However, we show that the residual radiated power can be reduced even more by placing two electric dipoles on opposite sides of the spherical scatterer. This paper might have implications for controlling radiative properties of emitters and implementing applications related to molecular localization and sensing.

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Electromagnetic sources beyond common multipoles

Cited by 40 publications

References 22 publications

Optical Anapoles: Concepts and Applications

Optical Anapoles: Concepts and Applications

The Observation of High-Order Charge–Current Configurations in Plasmonic Meta-Atoms: A Numerical Approach

Anapole arising from a Mie scatterer with dipole excitation

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