Silica colloidal crystals with uni- and multi-photonic bandgaps and controlled reflective properties

The present Letter introduces a new concept in the field of 3D photonic crystals, for the first time, we prepared the 3D silica colloidal crystals containing multi-photonic bandgaps. This is achieved by creating multiple layer structures of two (or more) colloidal crystals with different lattice parameters. Each layer will diffract lights of its characteristic wavelength and the reflectance spectra are expected to present as many reflectance peaks as the number of layers.