Broadband Tunable THz Absorption with Singular Graphene Metasurfaces

TL;DR

This paper presents a broadband, tunable terahertz absorber using singular graphene metasurfaces that achieve near-optimal efficiency over a wide frequency range, with strong field enhancement and subwavelength focusing capabilities.

Contribution

It introduces a novel design of graphene-based metasurfaces with singular conductivity modulations for broadband THz absorption, surpassing previous narrowband approaches.

Findings

Achieves 185% fractional bandwidth in THz absorption.

Exhibits strong field enhancement and high-order surface plasmon excitation.

Enables subwavelength focusing of THz radiation.

Abstract

By exploiting singular spatial modulations of the graphene conductivity, we design a broadband, tunable THz absorber whose efficiency approaches the theoretical upper bound for a wide absorption band with a fractional bandwidth of 185\%. Strong field enhancement is exhibited by the modes of this extended structure, which is able to excite a wealth of high order surface plasmons, enabling deeply subwavelength focussing of incident THz radiation. Previous studies have shown that the conductivity can be modulated at GHz frequencies, which might lead to the development of efficient high speed broadband switching by an atomically thin layer.