Pattern formation in a simple model of photochemical reaction

Stripe and columnar patterns were experimentally found in photopolymer films during irradiation of collimated UV light. We numerically study a similar pattern formation using a simple model of photochemical reaction. Microstuctures are self-organized owing to a new type of instability induced by the coupling between the refraction effect and the photochemical reaction. We perform two- and three-dimensional numerical simulations of model equations, and analyze the self-organized structures using concepts in nonlinear physics such as absolute instability and a soliton. Finally, we propose a more realistic model of photopolymerization. We found a spatially periodic columnar structure with numerical simulation, which is qualitatively similar to the pattern formation in the simple model.