Resonant properties of sub-wavelength metallic gratings

Sub-wavelength metallic gratings have extraordinary transmission efficiency and local field enhancement in resonant wavelengths. In order to deeply understand the resonant discipline, the resonant origins of the sub-wavelength metallic gratings were investigated. Three resonant wavelengths were analyzed by adjusting the geometric parameters and materials of the gratings, and the physical disciplines of three different resonant wavelengths were obtained. In the simulation, the periodical boundary method based on the boundary integral equation combined with a plane wave expansion method was used to process the period structures with arbitrary shapes. The numerical results show that three resonant center wavelengths can be tuned by the materials, periods, and the thicknesses of the gratings. It is believed that this study will provide useful information for further designing micro-nano optical elements.