The Research of Extraordinary Transmission Mechanism on Metallic Grating Structure Based on NS-FDTD

In order to eliminate the calculation error which is generated by the field point selection of finite-difference time-domain method on the interface of medium, this paper introduces a virtual field which is then unfolded by Taylor series, and gives the iterative formula of the nonstandard finite-difference time-domain method (NS-FDTD). The non-standard finite-difference time-domain method (NS-FDTD) is used to simulate plane wave irradiating vertically the novel sub-wavelength metal grating resonator, effects of the thickness of metal layer and the relative dielectric constant to extraordinary transmission characteristic are studied, and the extraordinary transmission mechanism is analyzed using the theory of Fabry-Perot cavity. A novel structure with extraordinary transmission characteristic is designed, and the extraordinary transmission characteristic in 450-900 THz band has also been studied using the method of NS-FDTD, the effect caused by some parameters such as thickness of metal layer, relative dielectric constant of dielectric layer has been given. The results show: as the thickness of the metal layer decreases, the factor of extraordinary transmission increases and moves towards high frequency, what's more, the factor moves towards low frequency as the relative dielectric constant of dielectric layer increases. This study provides a theoretical basis for further research on metal film and its extraordinary transmission mechanism.