Enhanced Optical Transmission Assisted Near-Infrared Plasmonic Optical Filter via Hybrid Subwavelength Structures

Enhanced optical transmission (EOT), which results from the incident light interacting with the subwavelength nanostructures patterned in a metallic film, showcases the excitation of surface plasmon modes on both surfaces of the metallic film and their intercoupling effects. Here, we numerically study the EOT phenomenon from the incident light acting on the periodic subwavelength hybrid arrays in a metallic film, which contains annular concentric core and aperture unit structure undergoing multiple geometrical configurations. It is shown that several configurations, which consist of a core with a different number of apertures, of the unit structure, are possible to facilitate the intercoupling between the surface plasmon polariton resonance mode of the core and the localized surface plasmon resonance mode of the aperture. Moreover, taking advantage of the EOT effect realized in the periodic structure arrays including a concentric core with triple-aperture unit structure, we propose a plasmonic optical filter (POF) in the near-infrared region. By adjusting both the periods and the width difference between the nearest-neighbor two apertures of the unit structure, the realization of near-infrared POF accompanies with tunable positions and amplitudes of the EOT peaks. Additionally, these behaviors could also be extended to the case of a concentric core with a multiple-aperture unit structure for actualizing near- or mid-infrared POF effect. Our results promise new avenues for plasmonic devices and enrich the application range of metallic structures in the field of optical communications and information processing.