Extremely High Q-factor metamaterials due to Anapole Excitation

TL;DR

This paper introduces a metamaterial design that exhibits near-infinite Q-factor due to anapole excitation, leading to extremely high local fields with minimal radiation losses.

Contribution

The authors design and fabricate planar metamaterials with anapole behavior, achieving unprecedented high Q-factors by canceling electric and toroidal dipole radiation.

Findings

Metamaterials exhibit extremely high Q-factors at resonance.

Local fields within the metamolecules are significantly amplified.

Size and parasitic radiation limit the Q-factor in practical designs.

Abstract

We demonstrate that ideal anapole metamaterials have infinite Q-factor. We have designed and fabricated a metamaterial consisting of planar metamolecules which exhibit anapole behavior in the sense that the electric dipole radiation is almost cancelled by the toroidal dipole one, producing thus an extremely high Q-factor at the resonance frequency. The size of the system, at the mm range, and the parasitic magnetic quadrupole radiation are the factors limiting the size of the Q-factor. In spite of the very low radiation losses the local fields at the metamolecules are extremely high, of the order of higher than the external incoming field.