A novel photonic crystal band‐pass filter using degenerate modes of a point‐defect microcavity for terahertz communication systems

Compact devices are important for the realization of terahertz communications systems. This article proposes a novel photonic crystal‐based device for realizing microminiature, high‐selectivity high Q band‐pass filters (BPF) and the design of a dual‐mode square lattice photonic crystal BPF that utilizes the degenerated modes of a point defect microcavity is presented. To design a high Q microcavity, the photonic band‐gap is initially calculated using the plane wave expansion method. Second, the eigenfrequencies and modal fields of a point defect microcavity that generates localized states in the band‐gap are calculated by a supercell method. Finally, the characteristics of mode splitting and the proposed dual‐mode BPFs are numerically studied by a full‐wave time‐domain method. © 2014 The Authors. Microwave and Optical Technology Letters Published by Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:792–797, 2014