Perfect Absorption in Ultrathin Epsilon-Near-Zero Metamaterials Induced by Fast-Wave Non-Radiative Modes

TL;DR

This paper demonstrates that ultrathin epsilon-near-zero metamaterials can achieve perfect absorption at wide angles through fast-wave non-radiative modes, enabling highly confined energy and tunable infrared absorption.

Contribution

It introduces a novel mechanism for perfect absorption in ultrathin epsilon-near-zero metamaterials via fast-wave non-radiative modes, with high confinement and tunability.

Findings

Achieves perfect absorption in ultrathin layers with high wavelength-to-thickness ratio

Confines electromagnetic energy in layers as thin as λ/10000

Tunes absorption wavelength from mid- to far-infrared

Abstract

Above-light-line surface plasmon polaritons can arise at the interface between a metal and epsilon-near-zero metamaterial. This unique feature induces unusual fast-wave non-radiative modes in a epsilon-near-zero material/metal bilayer. Excitation of this peculiar mode leads to wide-angle perfect absorption in low-loss ultrathin metamaterials. The ratio of the perfect absorption wavelength to the thickness of the epsilon-near-zero metamaterial can be as high as 10^4; the electromagnetic energy can be confined in a layer as thin as {\lambda}/10000. Unlike conventional fast-wave leaky modes, these fast-wave non-radiative modes have quasi-static capacitive features that naturally match with the space-wave field, and thus are easily accessible from free space. The perfect absorption wavelength can be tuned from mid- to far-infrared by tuning the epsilon = 0 wavelength while keeping the thickness of the structure unchanged.