Effective-medium description of disordered photonic alloys

We calculate the effective electric permittivity of photonic crystals of spherical particles with substitutional disorder. The effective permittivity is obtained by using a coherent-potential approximation scheme for photonic crystals in the context of multiple-scattering theory. The method is applied to the case of dielectric spheres in air as well as to inverted structures, i.e., air spheres in a dielectric medium. The results are compared against the standard Maxwell-Garnett effective-medium theory and its variations. (c) 2006 Optical Society of America.