A novel photonic crystal bandpass filter using degenerate modes of point-defect microcavity for terahertz communication system

A novel type of dual-mode square lattice photonic selectivity narrowband bandpass filters in the terahertz communication system. In order to design a high quality factor Q microcavity, the photonic bandgap is firstly calculated by using the PWE method. Secondly, the eigen-frequencies and EM fields of a point defect microcavity generating localized states in the bandgap are calculated by a supercell method. Finally, the property of mode separation of degenerate modes is investigated for photonic crystal point-defect microcavities and proposed dual mode bandpass filters are studied by TD-BPM and full-wave time-domain method.