Photopolymer Media Simulator for Holographic Data Storage using FDTD Method and Non-Local Polymerization Driven Diffusion Model

Abstract

We simulated the holographic data storage process using a photopolymer medium taking account of the polymerization and diffusion of the monomer. We used the FDTD method to construct our simulation, which adopts a new model which includes consideration of the polymer chain length and dark reaction. We analyze the dependency of physical mameters of the photopolymer medium, such as polymer chain length and diffusion coefficient, on holographic recording. We also estimate critical physical parameters of the photopolymer medium by fitting with expimental results. 1. Introduction Holographic data storage (HDS) has application to high density archival data storage and next generation consumer optical storage (I). Recent advances of HDS are supported by the progrss of photopolymer materials 121. We should consider monomer diffision and the process of polymerizing a holographic medium which has three stages, namely, initiation, propagation, and termhation and also the, so the temporal behavior of hologram recording is relatively complicated. To simulate the holographic recording process, various simulation methods taking account of monomer diffi~sion and polymmization have been proposed (2, 31. In this paper we propose a new model to simulate the holographc recordmg of a photopolymer and construct the simulator using the fink-difference time-domain (FDTD) method. We analyze difiaction efficiency as a function of the polymer chain length, the diffusion coefficient, and the difference between the refractive indices of monomer and polymer. We also estimate various physical parameters of the photopolymer medium by fitting the theoretical model to the experimental data. 2. Numerid model of the photopolymer simulator We adopt the non-local polymerization driven diffusion model (3,4) as the polymerization model, and revise this model by consi-g he dark rwcLion and kmhaion process LLner the beam illurnhalion. The 1-~enuioml non-local diffision equation considering the dark reactim is written as n(q,t,) = Cp@p(%,t,)+Cm@m(%,t,)~~~# 3 (6)