Suppression of light propagation in a medium made of randomly arranged   dielectric spheres
  Light propagation in a medium made of densely packed dielectric spheres is investigated by using a rigorous diffraction theory. It is shown that a substantial suppression of the local density of states occurs in spectral domains where the single constituents exhibit Mie resonances. The local density of states decreases exponentially at the pertinent frequencies with a linearly increasing spatial extension of the aggregated spheres. It is shown that a self-sustaining random arrangement of core-shell spheres shows the same fundamental characteristics. Such approach offers a path towards easy to fabricate photonic materials with omnidirectional gaps that may find use in various applications. 
Carsten Rockstuhl and Falk Lederer