EXTRAORDINARY TRANSMISSION THROUGH SUBWAVELENGTH HOLE ARRAYS FOR GENERAL OBLIQUE INCIDENCE - MECHANISM AS RELATED TO SURFACE WAVE DISPERSION AND FLOQUET LATTICE DIAGRAMS

An array of rectangular holes pierced through a conducting screen is treated herein by a rigorous full-wave modal analysis using the moment method entailing Green’s functions for rectangular cavities and planar multilayer structures in the spectral domain. Unexpectedly strong diffusions of incident plane waves are observed even at frequencies where the size of each hole is considerably less than the wavelength, posing a transmission efficiency that exceeds unity and thus leading to extraordinary transmission since this defies classical aperture diffraction theory. This paper fortifies the present understanding of the role surface plasmon polaritons (SPP) play in explaining this phenomenon, by using surface-wave dispersion and Floquet lattice diagrams to link up with the peaks in the transmission spectra. The incidence angle and polarization of the irradiation are taken into account in this work.