Diffraction processes in 3D photonic crystals based on thin opal films.

Coupling of polarized light to thin opal films was examined to characterize their crystalline structure and diffraction processes in them. Photonic stop bands were observed in transmission (reflection) spectra and attributed to diffraction from the {111} crystallographic planes of the twinned fcc structure. Weakening and collapses of stop bands for linearly polarized light demonstrated a strong anisotropy of light propagation in the films. Reflection spectra of the films under the s-polarized light illumination highlighted an unusual behavior of light scattering. Multiple Bragg diffraction accompanied by leakage and inflow of energy to major diffraction lobes has been detected and described in detail. [ABSTRACT FROM AUTHOR]