Fabrication of a three-dimensional terahertz wave photonic crystal by assembly monosized spherical particles

A photonic crystal is an artificial crystal with a periodic array of dielectric material. Such a crystal possesses a band gap for an electromagnetic wave with wavelengths corresponding to a lattice period. In this study, the photonic crystal with the spherical lattice of hundreds of micrometer-order corresponding to wavelengths of terahertz wave was fabricated by a template method. Monosized spherical copper particles were self-assembled into f.c.c. structure and sintered to form necks between adjacent particles. The array was impregnated with the resin whose dielectric constant was controlled. Subsequently to cure the resin, only the copper particles lattice was etched away by chemical dissolve. The obtained resin-inversed crystals were confirmed to exhibit a photonic stopgap along 〈111〉 direction by a terahertz wave spectroscopy. The frequency and gap width of measured gaps well agreed with the calculated ones by the plane wave expansion method.