Design and optimization of one-dimensional photonic crystal containing super-broad bandgap with defect structure

Aiming at prepare one-diamensional photonic crystal containing super-broad bandgap with defect structure, the one-dimensional photonic crystals, consisting of two kinds of oxide films, Al2O3 and TiO2, have been investigated. It is found that the photonic bandgaps can be greatly broadened using hetero-structure that containing defect layers. The defect-mode range within the bandgap caused by the defect layers can be compensated for by the photonic bandgap of a superposed photonic crystal that has a perfectly periodic structure. Thus, a broad bandgap is obtained. Broadened omni-directional bandgaps can also be realized by this method. In order to reduce the total number of layers of the hetero-structures, optimization of the structures has been carried out.