Generation of surface-plasmon-polariton like resonance mode on microwave metallic gratings

Abstract

In this work, transmission resonance modes in microwave metallic gratings are discussed with focus on the physical origins of the surface-plasmon-polariton (SPP)-like resonance mode and its relationship with the enhanced transmission phenomenon. A pseudoanalytical theoretical model using the surface impedance boundary conditions was introduced to characterize the electromagnetic (EM) diffraction of the grating, which was examined by a numerical calculation based on a finite element method. The numerically predicted near-field diffraction pattern as well as the photonic band diagram showed that the SPP-like mode in the microwave grating was of a hybrid mode character represented by the coupled resonance of bounded mode on the grating surface and localized standing wave inside the grating slit. Redistribution of the diffraction energy associated with the mode coupling would give rise to enhanced transmission efficiency when the standing wave inside the grating slit was strengthened. The results were compared with SPP-assisted light transmission over metallic optical aperture arrays. The present work is believed to contribute towards extending our understanding of the EM interaction in microwave photonic crystals.