Effect of Spatial Dispersion on Surface Waves Propagating Along Graphene Sheets

TL;DR

This paper analyzes how spatial dispersion influences surface wave propagation on graphene sheets, revealing significant effects on mode confinement and losses crucial for low THz plasmonic device design.

Contribution

It introduces a non-local model for graphene conductivity to accurately account for spatial dispersion effects in surface wave analysis.

Findings

Spatial dispersion significantly alters surface plasmon modes.

Mode confinement is affected by spatial dispersion.

Losses increase due to dispersion effects.

Abstract

We investigate the propagation of surface waves along a spatially dispersive graphene sheet, including substrate effects. The proposed analysis derives the admittances of an equivalent circuit of graphene able to handle spatial dispersion, using a non-local model of graphene conductivity. Similar to frequency selective surfaces, the analytical admittances depend on the propagation constant of the waves traveling along the sheet. Dispersion relations for the supported TE and TM modes are then obtained by applying a transverse resonance equation. Application of the method demonstrates that spatial dispersion can dramatically affect the propagation of surface plasmons, notably modifying their mode confinement and increasing losses, even at frequencies where intraband transitions are the dominant contribution to graphene conductivity. These results show the need for correctly assessing spatial dispersion effects in the development of plasmonic devices at the low THz band.