Directional Generation of Graphene Plasmons by Near Field Interference

TL;DR

This paper demonstrates a method for highly unidirectional excitation of graphene plasmons using near-field interference of orthogonally polarized dipoles, enabling controlled propagation directions for advanced plasmonic applications.

Contribution

It introduces a novel approach for directional graphene plasmon excitation via near-field interference and phase control, including practical implementation in nanowire/graphene systems.

Findings

Unidirectional excitation of GPs achieved through near-field interference.

Propagation direction switchable by phase difference or dipole placement.

Method applicable to arc graphene surfaces and nanowire/graphene systems.

Abstract

The highly unidirectional excitation of graphene plasmons (GPs) through near-field interference of orthogonally polarized dipoles is investigated. The preferred excitation direction of GPs by a single circularly polarized dipole can be simply understood with the angular momentum conservation law. Moreover, the propagation direction of GPs can be switched not only by changing the phase difference between dipoles, but also by placing the z-polarized dipole to its image position, whereas the handedness of the background field remains the same. The unidirectional excitation of GPs can be extended directly into arc graphene surface as well. Furthermore, our proposal on directional generation of GPs can be realized in a semiconductor nanowire/graphene system, where a semiconductor nanowire can mimic the circularly polarized dipole when illuminated by two orthogonally polarized plane waves.