Engineering Nanoparticles with Pure High-Order Multipole Scattering

Abstract

The ability to control scattering directionality of nanoparticles is in high demand for many nanophotonic applications. One of the challenges is to design nanoparticles producing pure highorder multipole scattering (e.g., octopole, hexadecapole), whose contribution is usually negligible compared to strong low-order multipole scattering (i.e., dipole or quadrupole). Here we present an intuitive way to design such nanoparticles by introducing a void inside them. We show that both shell and ring nanostructures allow regimes with nearly pure high-order multipole scattering. Experimentally measured scattering diagrams from properly designed silicon rings at near-infrared wavelengths (∼800 nm) reproduce well scattering patterns of an electric octopole and magnetic hexadecapole. Our findings advance significantly inverse engineering of nanoparticles from given complex scattering characteristics, with possible applications in biosensing, optical metasurfaces, and quantum communications.(This document is the unedited Author's version of a

Resonant Scattering Manipulation of Dielectric Nanoparticles

“…[ 109,172,173 ] The initial experimental results suggest that, given a specific cavity‐to‐nanoantenna ratio, the gap structure may lead to an extremely enhanced local magnetic field in the center of the antenna. [ 174,175 ] However, the design of dielectric nanoparticles that produce high‐order multipole scattering (e.g., octopole, hexadecapole) but suppressed dipole modes remains a challenging task. Typically, the contribution of high‐order multipole modes to resonance in the visible region is negligible compared to intense low‐order modes (e.g., ED and MD modes).…”

“…They showed that both ring and core–shell nanostructures supported almost pure high‐order multipole scattering. [ 175 ]…”

Pseudo-anapole regime in terahertz metasurfaces

“…Namely, spheres with different sizes of the voids were used to show prevailing electric or magnetic octopoles scattering. It was also shown experimentally that disks allow the observation of electric octopole and magnetic hexadecapole scattering, depending on the inner diameter [6].…”

Disentangling cathodoluminescence spectra in nanophotonics: particle eigenmodes vs transition radiation

“…In what follows, we choose to analyse the emission properties of Si NPs, because of their high refractive index and low Ohmic losses, 26 the multitude of co-existing modes in the visible 27,28 -with the field largely confined inside the NP, thus calling for traversing electron beams-and the relatively large sizes required for the full glory of all Mie resonances to unveil itself; 29 the combination of these features can significantly pronounce the interference effects under study. The spectra of Mie-resonant NPs are characterised by multipoles of both electric and magnetic character, 30 Fano resonances, 31 anapoles, 32 and bound states in the continuum, 33 and have enabled functionalities as diverse as directional light scattering 34,35 and emission, 36 directional couplers, 37,38 and Huygens-based metasurfaces.…”