The kinetics of photosensitive polymer holographic recording materials are examined assuming a material that exhibits nonideal kinetic behavior. Previously, a linear relationship between monomer concentration and polymerization was assumed when deriving the nonlocal polymer-driven diffusion (NPDD) model. This is consistent with ideal kinetic conditions in which chain termination is governed by a bimolecular process. However, these models have been reported to disagree with experimental results. In a limiting case of nonideal kinetics it is assumed that primary termination is dominant. In this case the NPDD model must be modified to incorporate a quadratic relationship between the monomer concentration and the polymerization rate. By use of a multiharmonic expansion method of solution the predictions of ideal (bimolecular or linear) and nonideal (primary or quadratic) kinetic models are compared. By using these models we carried out numerical fits to experimental growth curves of gratings recorded in an acrylamide-based cross-linked photopolymer system. Superior fits are achieved by use of the primary termination model. Physical parameters such as the diffusion constant are extracted and compared with results previously reported in the literature.
Photopolymers that absorb in the visible spectrum are useful for different applications such as in the development of holographic memories, holographic optical elements or as holographic recording media. Photopolymers have an undesirable feature, the toxicity of their components and their low environmental compatibility, particularly if we analyse the life cycle of the devices made with these materials and their interaction with the environment. In this work we developed a new photopolymer with photochemical and holographic features similar to those of the standard material but with an improved design from the environmental point of view.
The capability of polyvinyl alcohol–acrylamide photopolymer materials to obtain angularly multiplexed holographic gratings has been demonstrated [Appl. Phys. B 76, 851 (2003)]. A combination of two multiplexing methods—peristrophic and angular multiplexing—is used to record 60 holograms. An exposure schedule method is used to optimize the capability of the photopolymerizable holographic material and obtain holograms with a higher, more uniform diffraction efficiency. In addition, because of this exposure schedule method, the entire dynamic range (M#) of the material will be exploited, obtaining values of approximately in layers approximately thick.