Graphene, plasmons and transformation optics

TL;DR

This paper develops an analytical model using transformation optics to study subwavelength gratings for efficient coupling into graphene plasmons, considering various grating configurations and optimizing coupling conditions.

Contribution

It introduces a versatile analytical approach for modeling graphene plasmon coupling with gratings beyond shallow structures, including explicit dispersion and optical response expressions.

Findings

Derived explicit dispersion relations for graphene plasmon polaritons.

Identified optimal conductivity modulation for maximum coupling efficiency.

Analyzed reflectance and transmittance under plane wave illumination.

Abstract

Here we study subwavelength gratings for coupling into graphene plasmons by means of an an- alytical model based on transformation optics that is not limited to very shallow gratings. We consider gratings that consist of a periodic modulation of the charge density in the graphene sheet, and gratings formed by this conductivity modulation together with a dielectric grating placed in close vicinity of the graphene. Explicit expressions for the dispersion relation of the plasmon po- laritons supported by the system, and reflectance and transmittance under plane wave illumination are given. We discuss the conditions for maximising the coupling between incident radiation and plasmons in the graphene, finding the optimal modulation strength for a conductivity grating.