Resonance Analysis of a Surface Plasmon-Polariton Wave in a Prismatic Structure with a Limited Cross Section of a Test Beam

A method for analyzing the reflection of a limited cross-sectional beam from a multilayer structure has been developed. The method is based on the beam representation in the form decomposition of the plane waves using the discrete Fourier transform. The amplitude reflection coefficient from the multilayer structure is determined for each plane wave. The field distribution of the reflected beam is determined by the inverse discrete Fourier transform. This analyzes the incidence of a Gaussian beam on the metal film in the prism structure at resonant and non-resonant wavelengths that has been carried out by the proposed method. The spectral and angular dependences in the resonance region practically coincide with the corresponding dependences when the plane wave is incident on the metal film for the beam width of more than 1.5 mm. The reflection coefficient from the metal film is practically zero when the resonance conditions are satisfied.