Transmission of evanescent modes through a subwavelength aperture of a cylindrical waveguide. 1. Ideal metal approximation

The transmission of an evanescence electromagnetic wave through the subwavelength aperture of a dielectric cylindrical metal-coated waveguide is studied. In the ideal metal approximation a theoretical approach to the description of the field structure in a nanowaveguide is developed, which takes into account the transformation of the initial wave reflected from the output aperture. The complex reflection coefficient of a supercritical waveguide mode from the subwavelength aperture is calculated. The dependence of the field structure at the waveguide output on the ratio of its radius to the optical wavelength and on the dielectric constants of the waveguide core and the environment is found. The conditions for the appearance of a plasmon resonance in the presence of a medium with the negative dielectric constant in front of the input hole of the waveguide are found.