Efficient scattering model of multilayer systems with anisotropic films

We present an intuitive and efficient method for modeling light propagation in layered isotropic and anisotropic media, which we call the Iterated Ray Method. Considering a single layer sandwiched between semi-infinite layers, the infinite reflected and transmitted rays are summed to obtain effective Fresnel coefficients for the center layer. Thus, the system can be represented as two semi-infinite layers with an effective boundary. The model is coupled to a recursive algorithm to describe an arbitrarily large layered system in the same way. It is numerically stable in the presence of evanescent waves and computationally efficient, both in terms of operation counts and vectorization. We demonstrate its importance for the optical analysis and optimization of layered media, such as those used in photo-addressable liquid crystal cells, thin-film coatings, and Bragg gratings, by measuring the refractive index and thickness of a thin azobenzene dye photo-alignment layer, PAAD-22E, on an indium tin oxide coated glass slide.