A novel bandpass filter using higher-order degenerate modes of planar photonic crystal microcavity in terahertz regime

This paper presents a new dual-mode bandpass filter using higher-order degenerate resonant modes of a square lattice photonic crystal microcavity in terahertz frequency band. In order to design a photonic crystal high-Q microcavity, the dispersion relations of photonic bandgap are firstly calculated by using the plane wave expansion method. Secondly, the transmission properties of photonic crystal waveguides, microcavities and the proposed dual mode filters for THz applications are numerically investigated by using simplified TD-BPM and full-wave FDTD.