Incomplete Photonic Bandgap as Inferred from the Speckle Pattern of   Scattered Light Waves
  Motivated by recent experiments on intensity correlations of the waves transmitted through disordered media, we demonstrate that the speckle pattern from disordered photonic crystal with incomplete band-gap represents a sensitive tool for determination the stop-band width. We establish the quantitative relation between this width and the {\em angualar anisotropy} of the intensity correlation function. 
V. M. Apalkov, M. E. Raikh (University of Utah), B. Shapiro (Technion,   Haifa, Israel)