Fabrication and optical properties of silica shell photonic crystals

The relationship between silica shell thickness and optical properties of three-dimensional photonic crystals (3D PCs) is studied in this work. Core-shell spheres are synthesized by the modified Stöber method and self-assembled into 3D PCs through a simple improved vertical deposition method. Silica shell PCs are fabricated by sintering the PCs composed of the core-shell spheres. The morphologies and microstructures of PCs are identified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The transmission spectra of PCs are measured by UV–vis spectrum measurements (UV). The results show that the positions of Bragg diffraction peaks are shifted to a longer wavelength with the increase of silica shell thickness. The shift range of peak positions for silica shell PCs is wider than that for PCs of core-shell spheres. The main reason for this is because the variation range of effective refractive indices for silica shell PCs becomes larger than that for PCs of core-shell spheres.