  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.
