Three Dimensional Numerical Analysis of Optical Near Field in Bow-tie Type Nano-Aperture of a Metallic Layer

Abstract

Recently, a density growth is demanded in optical storage technologies. But, It is said that the upper limit of recording density by the current optical recording system is several tens of gigabits per inch square due to the optical diffraction limit even in the case of using a short wavelength. Then, as a technology that enables us to break down the optical diffraction limit, the optical near field technology has gotten a lot of attention. In this paper, we try to perform three-dimensional numerical analysis of an optical near field distributions in a metallic bow-tie type nano-aperture by using the FDTD method. In the present analysis, the FDTD method combined with the motion equation of electron is applied to a metallic medium whose permittivity can become negative at the optical wavelength range.