Effect of a photonic band gap in the optical range on solid-state SiO2 cluster lattices — opals

It is shown that synthetic opals — cubic face-centered lattices of SiO₂ clusters — are systems which exhibit a number of properties of photonic crystals in the visible-light range. By filling the voids (pores) in such lattices with different materials it is possible to vary the optical contrast of the medium and to obtain crystals of both the lattice of spheres type and its three-dimensional replica. It is shown that under conditions of identical optical contrast and in the presence of an additional optical inhomogeneity of the spheres, the transparency of the lattice of spheres is lower than that of its replica based on homogeneous media. A refractive index modulation of 1.266 was achieved in the lattice of spheres. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 7, 496–501 (10 April 1996)