Graphene-assisted metagrating: from coherent to angular-asymmetric control of absorption and reflection

TL;DR

This paper presents a reconfigurable graphene-based metagrating capable of coherent perfect absorption, dynamic beam steering, and asymmetric reflection, achieved through chemical potential tuning, enabling multifunctional optical control in a single planar device.

Contribution

It introduces a novel, tunable graphene metagrating that integrates multiple coherent functionalities, including reconfigurable absorption, beam steering, and asymmetric reflection, with simplified design and fabrication.

Findings

Achieves coherent perfect absorption at multiple angles.

Enables dynamic beam steering via chemical potential adjustment.

Demonstrates high retroreflection and asymmetric absorption.

Abstract

In this paper, we exploit the metagrating paradigm to achieve coherent control of absorption and reflection in a two-port device. Employing graphene ribbon as a tunable element allows us to, for the first time, realize a reconfigurable metagrating that integrates diversified coherent functionalities into a single planar structure. It is illustrated that the suggested design can behave as a coherent perfect absorber at multiple operating incident angles offered by its period-reconfigurability. Besides, our proposed metagrating is also capable of highly-efficient dynamic beam steering based on the coherent interaction of light with light through finely adjusting its chemical potentials, and its compatibility is then investigated to realize linear all-optical logic gates. Moreover, we use the idea of graphene-based metagrating to put forward an extremely asymmetrical device which exhibits high retroreflection upon illumination from one side and a strong absorption under excitation from the opposite side, revealing a great enhancement in design and fabrication simplicity compared to the previous works. The EM response of our suggested device can also be switched from a strongly asymmetric to a symmetric behavior by merely modulating the chemical potentials of its graphene ribbons.