Optical and terahertz near-field studies of surface plasmons in subwavelength metallic slits

Abstract

We studied the transmission of the electromagnetic waves through subwavelength slit arrays in terahertz ( THz) and optical frequency regions, respectively. In the optical frequency regime, the influences of surface plasmon polaritons on the near-field distribution and on the far-field transmittance are discussed. The near-field electro-optic sampling technique combined with fast Fourier transformation is applied in measuring the THz near-field distribution in time and spectral domains. From these, we discuss the existence of highly confined surface waves in the perfect conductor regime ( THz) in comparison with the finite conducting case (visible range) in metallic multi-slit arrays. Our studies provide an integrated view of surface plasmons in the optical regime, and surface-bound waves mimicking surface plasmons in the THz region.