Directional excitation of graphene surface plasmons

TL;DR

This paper presents a method to achieve directional excitation of graphene surface plasmons using a magneto-optical substrate and external controls, enabling active manipulation for opto-electronic applications.

Contribution

It introduces a novel scheme for unidirectional graphene plasmon excitation that is controllable via magnetic bias and electrical gating.

Findings

Asymmetric dispersion relation under magnetic field

Unidirectional excitation with normally incident light

Active control of directionality through electrical gating

Abstract

We propose a scheme to directionally couple light into graphene plasmons by placing a graphene sheet on a magneto-optical substrate. When a magnetic field is applied parallel to the surface, the graphene plasmon dispersion relation becomes asymmetric in the forward and backward directions. It is possible to achieve unidirectional excitation of graphene plasmons with normally incident illumination by applying a grating to the substrate. The directionality can be actively controlled by electrically gating the graphene, or by varying the magnetic bias. This scheme may have applications in graphene-based opto-electronics and sensing.