Excitation of Nonradiating Anapoles in Dielectric Nanospheres

Parker, J. A.; Sugimoto, Hiroshi; Coe, Brighton; Eggena, Daniel; Fujii, Minoru; Scherer, Norbert F.; Gray, Stephen K.; Manna, Uttam

doi:10.1103/physrevlett.124.097402

Cited by 56 publications

(41 citation statements)

References 49 publications

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“…[ 34 ] This corresponds to a fundamental limitation of the EDA design, since modes of resonators with inversion symmetry in the z ‐direction will always radiate as combinations of multipoles possessing even or odd parity, [ 60,61 ] and can only be overcome with careful tuning of the incident beam profile. [ 62 ]…”

Section: Resultsmentioning

confidence: 99%

Theory, Observation, and Ultrafast Response of the Hybrid Anapole Regime in Light Scattering

Valero

Gurvitz

Benimetskiy

et al. 2021

Laser & Photonics Reviews

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Modern nanophotonics has witnessed the rise of “electric anapoles” (EDAs), destructive interferences of electric and toroidal electric dipoles, actively exploited to resonantly decrease radiation from nanoresonators. However, the inherent duality in Maxwell equations suggests the intriguing possibility of “magnetic anapoles,” involving a nonradiating composition of a magnetic dipole and a magnetic toroidal dipole. Here, a hybrid anapole (HA) of mixed electric and magnetic character is predicted and observed experimentally via dark field spectroscopy, with all the dominant multipoles being suppressed by the toroidal terms in a nanocylinder. Breaking the spherical symmetry allows to overlap up to four anapoles stemming from different multipoles with just two tuning parameters. This effect is due to a symmetry‐allowed connection between the resonator multipolar response and its eigenstates. The authors delve into the physics of such current configurations in the stationary and transient regimes and explore new ultrafast phenomena arising at sub‐picosecond timescales, associated with the HA dynamics. The theoretical results allow the design of non‐Huygens metasurfaces featuring a dual functionality: perfect transparency in the stationary regime and controllable ultrashort pulse beatings in the transient. Besides offering significant advantages with respect to EDAs, HAs can play an essential role in developing the emerging field of ultrafast resonant phenomena.

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Section: Resultsmentioning

confidence: 99%

Theory, Observation, and Ultrafast Response of the Hybrid Anapole Regime in Light Scattering

Valero

Gurvitz

Benimetskiy

et al. 2021

Laser & Photonics Reviews

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“…Despite extensive research on toroidal excitations by the plane wave [31][32][33][34][35], structured light is of more interest due to its potential for exciting a dominant toroidal response in the geometrically simple nanosystems. It also enables new mechanisms and applications emerging in nanophotonics [26,[36][37][38][39]. We show that structured light can strongly interact with the dielectric nanodisk due to the contributions of radial and longitudinal components of the electric field supporting the oscillating displacement currents along the nanodisk's meridians.…”

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confidence: 92%

Structured light excitation of toroidal dipoles in dielectric nanodisks

et al. 2021

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Conventional electromagnetic multipoles can be completed by complementary sources of toroidal moments, opening the door to the engineering of a unique nanophotonic device group. The main contribution of this study is 3 comparing different light sources for enhancing the toroidal dipole response in a given system. We theoretically study the toroidal dipole excitation in an individual dielectric nanodisk by structured light illumination, including the tightly focused radially polarized beam and the focused doughnut pulse. The toroidal dipole and anapole can be excited by the interplay of the radial and longitudinal components of the incident light. As opposed to the plane wave illumination, the tightly focused radially polarized light can excite a near-ideal toroidal dipole while the contributions of the Cartesian electric dipole and other modes are significantly suppressed. We also show that the focused doughnut pulse is a promising tool for exciting a resonant toroidal response in nanophotonic systems. Furthermore, it is demonstrated that toroidal-driven field confinement leads to an enhancement of energy concentration inside the nanodisk that can potentially increase light harvesting and boost both linear and nonlinear light-matter interactions.

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“…We also show that angle-and polarization-resolved scattering measurements allow us to separately detect ED and MD resonances. Although separate detection of ED and MD resonances of a nanoobject is possible by an attenuated total reflection (ATR) configuration, [41] by using specifically tailored vector beams, [42][43][44][45] and by cathodoluminescence (CL), [32] the setup developed in this work provides more comprehensive information under plane wave irradiation without utilizing special configurations and optical components. The setup can be applied to a nanoobject with any shape and can provide valuable information for the development of a nanoantenna and a metasurface.…”

Section: Introductionmentioning

confidence: 99%