Inhibited Light Propagation and Broadband Reflection in Photonic Air-Sphere Crystals

Abstract

We have performed optical reflectivity experiments and band structure diffraction calculations on fcc photonic crystals, consisting of air spheres in titania ( $\mathrm{TiO}{}_2$). The spectra reveal Bragg peaks whose large widths agree well with the calculations. The peaks overlap in many directions, causing the propagation of light to be limited by Bragg reflection to $45\%$ of the $4\pi$ solid angle. This illustrates that the air-sphere crystals interact so strongly with light that an unprecedented limitation in the directions of propagation of light in photonic crystals is achieved.