Holographic recording in charged photopolymerisable nanocomposites
Document Type Conference Paper
T. Yovcheva, I Vlaeva, S. Sainov, I. Naydenova, V. Toal, S. Mintova, Holographic recording in charged photopolymerisable nanocomposites, Conference proceedings of the International commission for Optics Topical meeting on Emerging trends and novel materials in photonics, v.1288, 39-42, 2009.
Self – processing photopolymers have a large number of different applications due to their versatile properties as holographic recording materials. A significant effort has been directed towards the development of photopolymers for holographic data storage [1, 2], holographic sensors , holographic optical elements  and display holograms . The Centre for Industrial and Engineering Optics has been developing acrylamide based photopolymers for the last decade [6-8]. The main parameters requiring improvement in these types of photopolymers are their dynamic range and their mechanical stability during the holographic recording. Recently we have successfully used zeolite nanoparticles as dopants in order to increase the dynamic range and lower the shrinkage in acrylamide-based photopolymers . The advantages of using zeolite nanoparticles in colloidal form are their stability in water suspension: they have the same pH as the photopolymer and can be synthesized with different shape, size and chemical composition. Depending on the chemical composition and types of the structure, the zeolites will exhibit variable refractive index. Among the different types of zeolite nanoparticles used for doping of photopolymers, the pure silica MFI (Si-MFI) has shown the best results . Having in mind that the zeolites are negatively surface charged it is expected to be an appropriate dopant for photopolymers . We studied the effect of the charging of the photosensitive layers on their holographic recording properties. The charging was achieved by exposure to corona discharge. Different types of charges – positive and negative were deposited on the layer surfaces. It was observed that their presence influences the diffraction efficiency of recording.