Photonic band gap in the face-centered cubic lattice of spherical shells connected by cylindrical tubes

We found a three-dimensional photonic crystal model, i.e., a non-close-packed face-centered cubic lattice of hollow spheres connected by thin cylindrical tubes, which possesses a complete three-dimensional photonic band gap between the eighth and ninth bands using photonic band structure calculations. The relative gap width reaches 9.1% at the low dielectric contrast of 7.84 appropriate to the transparent titania, and the minimum dielectric contrast needed to open the gap is about 5.3.