Tunable Graphene Metasurface Reflectarray for Cloaking, Illusion and Focusing

TL;DR

This paper introduces a tunable graphene metasurface capable of dynamically switching between cloaking, illusion, and focusing functionalities through electrostatic gating, without altering its physical structure.

Contribution

It presents a novel graphene-based metasurface design that achieves active tuning of optical properties via electrical bias, enabling versatile wavefront control.

Findings

Demonstrated cloaking of a triangular bump with tunable wavefronts

Achieved dynamic beam steering and focusing

Controlled reflection direction through electrical bias

Abstract

We present a graphene-based metasurface that can be actively tuned between different regimes of operation, such as anomalous beam steering and focusing, cloaking and illusion optics, by applying electrostatic gating without modifying the geometry of the metasurface. The metasurface is designed by placing graphene nano-ribbons (GNRs) on a dielectric cavity resonator, where interplay between geometric plasmon resonances in the ribbons and Fabry-Perot resonances in the cavity is used to achieve 2$\pi$ phase shift. As a proof of the concept, we demonstrate that wavefront of the field reflected from a triangular bump covered by the metasurface can be tuned by applying electric bias so as to resemble that of bare plane and of a spherical object. Moreover, reflective focusing and change of the reflection direction for the above-mentioned cases are also shown.