Analysis of Trapped-Mode Resonances of Light Diffraction by Two-Periodic Planar Structure of Asymmetric Metal Elements

Abstract

Normally incedent wave diffraction by planar periodic structure of two small asymmetrical metal complex-shaped elements has been solved numerically for optical and infra-red ranges. The Fourier mapped pseudospectral time-domain method combined with auxiliary differential equations technique and complex pole model are used for taking into account the dispersion of metal permittivity. The trapped mode resonances forming in structures is shown possible. The Q-factor of this type resonance is higher than that of plasmon-polariton resonance of planar structures of single metal element periodic cell. The existence of higher order trapped mode resonance which Q-factor is greater than the that of corresponding fundamental trapped mode resonance is first shown.