Computational Analysis of Electric Field Distribution in Dual-Layered Phase-Change Disc

• DOI: 10.1364/ods.2003.tue42p
• Publication Date: 2014-12-04T13:15:47Z
• Authors: Sumitaka Maruyama; Masatoshi Hirono; Keiichiro Yusu; Takayuki Tsukamoto; Naoki Morishita; Masahiko Tanaka; Hiroharu Satoh
• Keywords: 0211 other engineering and technologies; 02 engineering and technology

Abstract: We developed a Finite-Difference Time Domain (FDTD) Method based simulator thatcan analyze Dual-Layered phase-change disc structure. Because of a substrate thickness error, it isnecessary to consider spherical aberration. The electric field distributions have been calculated onSingle-Layered and Dual-Layered phase-change discs. We found differences between the electric distributions focused on a groove and on a land. These calculation results can explain the corresponding experimental results clearly.Keywords: Finite-Difference Time Domain (FDTD), spherical aberration, vector diffraction theory,phase change optical recording, high capacity disc 1. Introduction A system using 20GB next-generation optical disc system in which the NA is 0.65, the wavelength is 405nm and thesubstrate thickness is 0.6mm has been developed [1]. However, there is strong demand for even larger recordingcapacity. A Dual-Layered optical disc may double the capacity by recording on two layers from the same readoutside of a disc. For higher recording density media, rigorous vector diffraction calculations are useful in order tocalculate the exact electromagnetic distributions in the Recording Layer. Many such calculations have been doneusing various methods, such as FMM (Fourier Modal Method)[2] and the FDTD (Finite-Difference Time Domain)Method [3]. However, a calculation regarding Dual-Layered optical disc hasn't been developed.In Dual-Layered disc, because the substrate thickness differs from 0.6mm in each Recording Layer, it is necessary toconsider spherical aberration. In the work reported in this paper, we developed a computer simulation code in whichthe FDTD Method is applied that can calculate the behavior near the Recording Layer for land and groove recording,considering spherical aberration. Using this simulator we compared the electric field distributions focused on agroove and a land.