Probing terahertz surface plasmon waves in graphene structures

TL;DR

This paper uses terahertz nearfield microscopy to study surface plasmon waves in graphene structures, revealing sub-wavelength property variations and edge excitations, with implications for THz transmission control.

Contribution

It demonstrates the use of THz nearfield microscopy to probe surface plasmons and transmission properties in graphene structures at sub-wavelength scales.

Findings

Surface plasmon excitation occurs at graphene edges.

Graphene ribbons alter Fresnel reflection and THz transmission.

Sub-wavelength property variations are observed in graphene.

Abstract

Epitaxial graphene mesas and ribbons are investigated using terahertz (THz) nearfield microscopy to probe surface plasmon excitation and THz transmission properties on the sub-wavelength scale. The THz near-field images show variation of graphene properties on a scale smaller than the wavelength, and excitation of THz surface waves occurring at graphene edges, similar to that observed at metallic edges. The Fresnel reflection at the substrate SiC/air interface is also found to be altered by the presence of graphene ribbon arrays, leading to either reduced or enhanced transmission of the THz wave depending on the wave polarization and the ribbon width.