Three‐Dimensional Stereolithography of Alumina Photonic Crystals for Terahertz Wave Localization

Using stereolithography as an additive manufacturing ( AM ) process, photonic crystals, with a diamond‐like structure composed of alumina microlattices, were fabricated and their electromagnetic band gap profiles, in terahertz frequency ranges, were investigated. Acrylic resins with dispersed alumina particles were fabricated by stereolithography with micrometer‐order accuracy. After dewaxing and sintering processes, alumina lattices were obtained with high relative densities that reflected the terahertz waves, through Bragg diffraction, perfectly in all directions. Twinned crystal structures with mirror symmetric diamond lattices were designed to introduce defect interfaces. Double‐cavity defects consisting of unit cells hollowed from the diamond lattices formed the coupled resonation modes.