Electromagnetic Properties of Photonic Crystals Composed of Normal and Inverse Diamond Structure with Graded Lattice Spacings

Millimeter order photonic crystals composed of epoxy lattices containing titania-based ceramic particles and having a three-dimensional diamond structure were fabricated by using a stereolithograpy process. The inverse diamond structures composed of the air lattices with the diamond structure in dielectric bulks were also processed which exhibited perfect bandgaps in microwave frequency range. The normal and inverse lattice structures were stretched gradually to diffract the microwave in wide ranges. These graded lattice structures were designed according to the band calculation using a plane wave propagation method. An electromagnetic filter composed of the graded lattice structure with a missing layer realized the selective transmission of the microwave.