Photopolymer material used in the recording of slanted gratings

Abstract

Photopolymer materials are practical materials for use as holographic recording media, as they are inexpensive and selfprocessing. By understanding the mechanisms present during recording in these materials their limitations for certain processes can be improved and a more efficient, environmentally stable material can be produced. Understanding the photochemical and photo-physical processes present during the formation of holographic gratings in photopolymer materials is crucial in enabling further development of holographic applications such as data storage, metrology, free space optical components etc. In order to achieve this, it is necessary to develop material electromagnetic theory, which models these applications. In this paper we begin by experimentally estimating parameters associated with absorption due to dye in the photopolymer. This information is needed when using Non-local Photo-Polymerization-Driven Diffusion model (NPDD) to characterise such materials. Absorption also leads to the formation of non-uniform tapered grating structures. While the NPDD has been used to characterise materials recording slanted gratings problems have arisen in determining diffusion constants accurately. In order to deal with electromagnetic diffraction by the resulting non-uniform slanted grating structures we develop first order analytic expressions governing the replay of such gratings.