Transmission of evanescent modes through a subwavelength aperture of a cylindrical waveguide. 2. The influence of dielectric properties of a real metal

The transmission of an evanescent light wave through the subwavelength aperture of a dielectric cylindrical metal-coated waveguide is studied. The theoretical approach to the description of the field structure in such a nanowaveguide is developed, which takes into account the transformation of the initial wave reflected from the output aperture and proves applicable when dielectric properties of a real metal are taken into account. The complex reflection coefficient of a supercritical waveguide mode from the aperture, the complex light flow and the far-field transmission coefficient are calculated for an aluminium-coated waveguide at the light wavelength of λ = 488 nm. It is established that the reflection and transmission coefficients of the nanowaveguide strongly depend on the dielectric constant of its core and differ significantly for transverse-magnetic and transverse-electric modes. It is demonstrated that the characteristics of light fields under study differ essentially from those of a nanowaveguide with ideally conducting walls and the subwavelength aperture in a perfectly conducting screen.