Surface Plasmon Propagation on a Film with Subwavelength Holes in the Terahertz Frequency Range

We experimentally study the propagation of surface plasmons on a metal foil containing subwavelength structures in the terahertz frequency range. Additional measurements of the transmission spectra through the same structures allowed us to determine the effective dielectric function of the structured layer for the two directions of wave propagation, along and across the film surface. It was shown for the first time that even a thin two-dimensional film of metal with slits may reduce the surface plasmon velocity and enhance the spatial localization of the plasmon field at the surface.