Bragg diffraction of light in high-quality synthetic opals

The complicated angular and spectral dependencies of scattering of oriented light beams on three-dimensional diffraction grating of synthetic opals were observed experimentally and interpreted theoretically. The results demonstrate the main role of Bragg reflections on several systems of closest-packed (111)-type atomic planes of twinned FCC lattice, built from a-SiO2 spheres in the condition of one-dimensional disorder in the packing of (111) layers, perpendicular to the growth axis of the sample.