A three-dimensional photonic crystal operating in the visible region

Photonic bandgap materials have received considerable attention due to thei r ability to confine and control electromagnetic waves in all three spatial directions. The material reported here (see Fig.) is a cubic-close-packed (ccp) lattice assembled from 215 nm polystyrene beads whose surfaces have b een doped with the organic dye Oil Blue N. The method gives large-area crys tals and allows the tuning of the photonic bandgap through variation of dop ant and bead size (see Cover).