Toward Monoatomic-Layer Field Confinement Limit via Acoustic Graphene Plasmons

TL;DR

This paper proposes methods to selectively excite acoustic plasmons in double-layer graphene, aiming to achieve ultimate plasmonic confinement at the monoatomic level, surpassing previous architectures.

Contribution

It introduces strategies and an analytical model for efficient acoustic plasmon excitation and presents an optimal device design for experimental observation of extreme confinement.

Findings

Analytical model clarifies emitter position effects on plasmon symmetry

Strategies enable selective excitation of acoustic plasmons

Designs approach monoatomic-layer confinement limit

Abstract

Vertical plasmonic coupling in double-layer graphene leads to two hybridized plasmonic modes: optical and acoustic plasmons with symmetric and anti-symmetric charge distributions across the interlayer gap, respectively. However, in most experiments based on far-field excitation, only the optical plasmons are dominantly excited in the double-layer graphene systems. Here, we propose strategies to selectively and efficiently excite acoustic plasmons with a single or multiple nano-emitters. The analytical model developed here elucidates the role of the position and arrangement of the emitters on the symmetry of the resulting graphene plasmons. We present an optimal device structure to enable experimental observation of acoustic plasmons in double-layer graphene toward the ultimate level of plasmonic confinement defined by a monoatomic spacer, which is inaccesible with a graphene-on-a-mirror architecture.