Light Transportation in cellular structures

Based on geometrical ray optics, light propagation through a foam is investigated by using random walk theories and simulations. Experiments by Gittings, Bandyopadhyay and Durian [EPL 65, 414 (2004)] show that light possesses a higher probability to propagate in the liquid films. To model the extrem case of such a photon channelling, in the first part of this work, all photons are completely reflected at each liquid-air interface so that they only move within the films. In the second part, reflection and transmission with probabilities according to Fresnel's formulas are allowed. In both cases, simulations of the photons in a perfect honeycomb structure reveal superdiffusive behavior which we also explain within the theory of Levy walks. In disordered lattices, light transport is, however, diffusive and depends strongly on the amount of disorder