2005/05/31 by Michael Schmiedeberg, MirFaez Miri, M. Jahan Miri +1 · 1 citation
Materials Science · Physics and Astronomy · #Material Dynamics and Properties #Random lasers and scattering media #Theoretical and Computational Physics #cond-mat.soft
paper · pdf · doi:10.1140/epje/i2005-10034-6
published as Eur. Phys. J. E 18, 123-131 (2005) · 9 pages, minor changes
openalex publication_date 2005/09/01 · arxiv created 2005/10/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Experiments by Gittings, Bandyopadhyay, and Durian [Europhys. Lett. 65, 414 (2004)] demonstrate that light possesses a higher probability to propagate in the liquid phase of a foam due to total reflection. The authors term this observation photon channelling which we investigate in this article theoretically. We first derive a central relation in the work of Gitting \em et al. without any free parameters. It links the photon's path-length fraction f in the liquid phase to the liquid fraction ε. We then construct two-dimensional Voronoi foams, replace the cell edges by channels to represent the liquid films and simulate photon paths according to the laws of ray optics using transmission and reflection coefficients from Fresnel's formulas. In an exact honeycomb foam, the photons show superdiffusive behavior. It becomes diffusive as soon as disorder is introduced into the foams. The dependence of the diffusion constant on channel width and refractive index is explained by a one-dimensional random-walk model. It contains a photon channelling state that is crucial for the understanding of the numerical results. At the end, we shortly comment on the observation that photon channelling only occurs in a finite range of ε.