Theoretical study of transmission characteristics of sub-wavelength nano-structured metallic grating

Some unique optical properties of sub-wavelength nanometer-sized metallic grating are presented in this paper. We propose a model to predict and explain the transmission of transverse-magnetic polarized light through a metallic grating with no substrate in the visible and near-infrared region. The model is based on a theoretical combination of surface plasmon polariton resonance and Fabry-Perot (FP)-like resonance that was excited by the nano-slit located in the grating. The finite difference time domain method is employed for modeling and simulation, and the minimum and maximum characteristics are analyzed, which shows its extraordinary enhanced transmission that differs from the conventional micrometer-sized metallic grating. This model can also be used to optimize the structural parameters in the design of the sub-wavelength wire-grid polarizer.