Plasmonic properties of graphene on uniaxially anisotropic substrates*

Abstract

Most of the current graphene plasmonic researches are based on the substrates with isotropic dielectric constant such as silicon. In this work, we investigate optical properties of graphene nanoribbon arrays placed on a uniaxially anisotropic substrate, where the anisotropy provides an additional freedom to tune the behaviors of graphene plasmons, and its effect can be described by a simple effective formula. In practice, the substrates of semi-infinite and finite thickness are discussed by using both the formula and full wave simulations. Particularly, the dielectric constants ε ∥ and ε ⊥ approaching zero are intensively studied, which show different impacts on the transverse magnetic (TM) surface modes. In reality, the hexagonal boron nitride (hBN) can be chosen as the anisotropic substrate, which is also a hyperbolic material in nature.

High-efficiency light manipulation using a single layer of folded graphene microribbons

“…In order to demonstrate the proposed functionalities solely from FGMRs, and for simplicity, the surroundings (including the substrate) are set to be air. Besides its supporting role, the substrate will produce a global screening to local resonances on FGMRs [61][62][63], which will lead to a slight redshift of the operating frequencies, but these functionalities can be well maintained. Regarding the bottom gate for electrostatic gating [64], instead of the metal layer, a conductive yet transparent electrode, e.g., indium tin oxide (ITO) [65], can be employed.…”

Plasmonic coupling in graphene nanoribbon dimers

“…Because of the 2D nature of graphene, plasmonic resonances in graphene nanostructures exhibit extremely strong light confinement and enhancement, for instance the size of graphene resonators is often two orders of magnitude smaller than the free-space wavelength [25]. However, the plasmonic resonances in graphene usually suffer from the issue of narrow bandwidth, which dramatically limits their capabilities in light manipulation [26][27][28]. One promising solution is to integrate resonators of different frequencies in one unit cell [29], in which the mutual coupling between these resonators is of great importance.…”