# Graphene epsilon-near-zero plasmonic crystals

## TL;DR

This paper explores graphene-based plasmonic crystals exhibiting epsilon-near-zero behavior, demonstrating how their optical properties can be dynamically tuned and expanded across a broad frequency range through a novel construction approach.

## Contribution

It introduces a new method to extend the ENZ frequency range in graphene plasmonic crystals by combining a Lorentzian host material with graphene's Drude-model conductivity.

## Key findings

- ENZ behavior can be achieved over a large frequency range
- Optical properties are tunable via frequency and doping level
- Combination of Lorentzian response with graphene conductivity enhances ENZ span

## Abstract

Plasmonic crystals are a class of optical metamaterials that consist of engineered structures at the sub-wavelength scale. They exhibit optical properties that are not found under normal circumstances in nature, such as negative-refractive-index and epsilon-near-zero (ENZ) behavior. Graphene-based plasmonic crystals present linear, elliptical, or hyperbolic dispersion relations that exhibit ENZ behavior, normal or negative-index diffraction. The optical properties can be dynamically tuned by controlling the operating frequency and the doping level of graphene. We propose a construction approach to expand the frequency range of the ENZ behavior. We demonstrate how the combination of a host material with an optical Lorentzian response in combination with a graphene conductivity that follows a Drude model leads to an ENZ condition spanning a large frequency range.