High Intensity Response of Photopolymer Materials for Holographic Grating Formation

In order to further develop the understanding of photopolymer materials, a more complete physical model has become necessary In particular, a more accurate description of the photochemical mechanisms occuring during the photopolymerization processes is needed Generally, in photopolymers the photosensitizer absorbs light of an appropriate wavelength, becoming excited and causing the production of primary radicals R In free radical polymerization systems the generation of R is a key factor in determining how much monomer is polymerized This in turn is closely related to the refractive index modulation formed during holographic recording In this article we Incorporate a detailed photoinitiation model into the nonlocal photopolymerization driven diffusion (NPDD) model This model describes the following (1) Photon absorption behavior and primary radical generation during initiation, (2) nonlocal macro radical chain growth through propagation, (3) oxygen diffusion and replenishment for inhibition (4) multiple termination mechanisms This extended model is experimentally validated for high intensity holographic exposures to a polyvinylalcohol/acrylamide based photopolymer material