Study of effective optical thickness in photopolymer for application

The impact of the effective optical thickness of a photopolymer on its holographic performance was studied. To overcome the attenuation of gratings for a better uniformity, a multilayer approach was introduced, by adjusting concentrations of dye along the depth of photopolymer to compensate the attenuation of recording light due to absorption. Multilayer photopolymers with thicknesses over 500 μm were designed, fabricated, and characterized experimentally, exhibiting better Bragg selectivity. More holograms were stored in multilayer material by angular multiplexing, and the cumulative grating strength was enhanced, leading towards larger holographic storage capacity.