Excitation of radiationless anapole mode of isotropic dielectric nanoparticles with tightly focused radially polarized beam

TL;DR

This paper demonstrates a method to excite radiationless anapole modes in high index dielectric nanoparticles using tightly focused radially polarized beams, enabling control over scattering properties for nanophotonics applications.

Contribution

It introduces a novel excitation technique for radiationless anapole modes in dielectric nanospheres using focused radially polarized beams and standing wave configurations.

Findings

Electric dipole and magnetic modes can be suppressed to achieve near-zero scattering.

Standing wave illumination enables excitation of ideal radiationless anapole.

The method allows precise control of scattering in dielectric nanoparticles.

Abstract

A high index dielectric nano-sphere can be excited and yet remain radiationless. A method to excite the non-radiating anapole mode of a high index isotropic dielectric nanosphere is presented. With tightly focused radially polarized beam illumination, the main-contributing electric dipole mode and magnetic modes can be zero with only a weak electric quadruple contributing to the total scattering. Further, with a standing wave illumination formed by two counter-propagating focused radially polarized beam under $4\pi$ configuration, the ideal radiationless ananpole can be excited.