<title>Epoxy-photopolymer composites: thick recording media for holographic data storage</title>

Abstract

Archival data-storage based on holographic methods requires high performance recording materials. Here, we describe an epoxy-photopolymer composite material which is sensitive to visible light and can be fabricated as thick films. These materials are prepared by combining photopolymerizable vinyl monomers with a liquid epoxy resin and an amine hardener. As the epoxy cures at room temperature, a solid matrix is formed which surrounds the unreacted photopolymer. These vinyl monomers are subsequently photopolymerized during hologram recording. Typically the material consists of a low index matrix, composed of diethylenetriamine and 1,4- butanediol diglycidyl ether, and a high index photopolymer mixture of N-vinylcarbazole and N-vinyl-2-pyrrolidinone. Because the polymers can be prepared in thick formats, narrow angular bandwidth holograms with high diffraction efficiency can be recorded. A dynamic range up to 13 has been measured in these materials.