Improved Broadband Near-Unity Light Transparency of a Metal Layer With Film-Coupled Dual Plasmonic Arrays

Abstract

We report improved light transparency over a broad bandwidth in a metal-layered structure with two film-coupled subwavelength non-close-packed plasmonic arrays. Through the introduction of dual ultrathin dielectric spacing layers between the metal layer and the double plasmonic disk arrays, coupling of the input and output effects of light is efficiently enhanced through strong near-field localized plasmon resonances between adjacent plasmonic disks and the near-field plasmon cavity mode in the gap between the double plasmonic arrays and the metal layer. A broad bandwidth of 300 nm with near-unity light transmittance (above 90%) in the optical regime is achieved through the localized plasmon resonances and the symmetrical structure used here. The transparency of this structure is polarization independent and incident angle insensitive, and can be tuned by varying the structure parameters and the dielectric environment. In addition, the period of the plasmonic arrays and the thickness of the nanometer-separated plasmonic structure are less than λ /20 and λ/8, respectively. These values suggest that the proposed structure may have potential applications in deep subwavelength optoelectronic devices, including broadband optically transparent electrodes, highly integrated light input and output components, and plasmonic filters.