Numerical investigation of nonlinear shrinkage effects in volume holographic gratings

Photopolymers are widely used as a recording medium in holographic data storage, but they shrink during polymerization. We proposed a nonlinear shrinkage model to numerically evaluate the effect of photopolymer shrinkage on signal quality. Specifically, we developed both a numerical model in which the shrinkage factor is determined locally according to the light intensity, and a numerical simulation method that can handle computational lattices distorted by shrinkage. We clarified the influence of shrinkage on diffraction efficiency, angle selectivity, wavelength selectivity, signal-to-noise ratio, and symbol error rate. This study provides useful information for system design of holographic data storage.