Photonic bandgap extension of surface-disordered 3D photonic crystals based on the TiO_2 inverse opal architecture

摘要

A photonic bandgap (PBG) extension of surface-disordered 3D photonic crystals (PCs) based on the TiO_2 inverse opal (TiO_2-IO) architecture has been demonstrated. By using a liquid phase deposition (LPD) process based on the controlled hydrolysis of ammonium hexafluorotitanate and boric acid, an extra layer of TiO_2 nanoparticles were deposited onto the internal surface of the air voids in the TiO_2-IOs to increase their surface roughness, thereby introducing surface disorder in the 3D order structures. The PBG relative width of surface-disordered TiO_2-IOs has been broadened significantly, and, compared to the original TiO_2-IO, its largest rate of increase (27%) has been obtained. It was found that the PBG relative width increased rapidly at first and then to a much slower rate of change with increase of the duration of the LPD time. A possible cause for this finding is discussed in this Letter.