Disorder-immune metasurfaces with constituents exhibiting the anapole mode

TL;DR

This paper presents disorder-immune optical metasurfaces made of core-shell cylinders that maintain their reflective properties despite random displacements, due to weak non-local effects and non-radiating anapole modes.

Contribution

The authors demonstrate a novel design of metasurfaces that are immune to positional disorder by leveraging anapole modes and weak multiple scattering effects.

Findings

Metasurfaces retain performance under random displacements.

Reflection properties are insensitive to spacing variations.

Disorder immunity is due to weak non-local effects and anapole modes.

Abstract

Common optical metasurfaces are 2-dimensional functional devices composed of periodically arranged subwavelength constituents. Here, we achieved the positional-disorder-immune metasurfaces composed of core-shell cylinders which successively exhibit the magnetic dipole (MD) resonant, non-radiating anapole, and electric dipole (ED) resonant modes when their outer radii are fixed and the inner radii changes continuously in a range. The performances of the metasurfaces under a periodically structural design are not degraded even when the positions of the cylinders are subjected to random and considerable displacements. The positional-disorder-immunity is due to the weak non-local effect of the metasurfaces. Because the multiple scattering among cylinders is weak and insensitive to the spacing among the cylinders around the ED and MD resonant modes and vanishing irrespective of the spacing at the non-radiating anapole mode, the reflection properties including the reflection phase and reflectivity of the metasurfaces are insensitive to the spacing between neighboring cylinders for this entire variation range of the inner radius. The positional-disorder-immunity make the metasurface to be adapted to some unstable and harsh environments.