PHOTONIC CRYSTAL MADE BY CLOSE PACKING SIO2 SUBMICRON SPHERES

Three-dimensional solid superstructures built with submicrometric SiO2 spheres ordered in a close packed arrangement are shown to behave as photonic crystals. Spheres are synthesised following the Stober-Fink-B ohn method. A close packed structure with a perfect short-range order (tens of microns) is then obtained by sedimentation, on suitable subst rates. Specular reflectance of visible light is found to follow Bragg' s law which indicates that these structures behave as photonic crystal s. This work shows that the ordering of microparticles can be a method to build photonic bandgap materials. (C) 1997 Academic Press Limited.