Effects of structural parameters in metallic nano slit arrays

Nano slit arrays perforated on thin metallic film are the basic structure of metallic nano-optic lenses, which resemble the shape of the conventional glass lens, and can be applied to beam manipulation, such as beam reflecting/deflecting or focusing. It has been proven that optical transmission is feasible through metallic nano slit arrays, making new nano technology applications possible. In conventional dielectric lenses, the edge effect-the very strong diffraction of the transmitted beam that take place at the lens edges restricts the possibility of sizing down the conventional optics components to a sub-wavelength range. This is due to the fact that the size of the lens is an important determinant of focusing beam to the nano scale. In this paper we present the metallic nano lenses and study their optical transmission properties. These lenses do not suffer from the edge effect mentioned above. The phase of each nanoslit element can be managed by changing the material of the metal film and/or the structural parameters of the lens. In our simulation work, we examine the transmission performance of metallic nano slit arrays by the method of finite-difference time-domain (FDTD). We use various metals such as copper, silver, aluminum and titanium as the material of the thin films. We also investigate various structural parameters such as slit number, width and thickness, to show their influence on the optical transmission performance. By adjusting the material and/or structural parameters of the Nano slit arrays, the desired transmission performance can be realized.