Design of pseudo-elliptic bandpass filter using higher-order modes of photonic crystal point defect cavity for sub-terahertz bands

In this paper, a novel compact 2D photonic crystal bandpass resonant filter is proposed and designed on the basis of coupling matrix theory between the waveguide and point defect resonators with perturbing dielectric posts. The coupling matrix concept offers an accurate method for a direct synthesis of narrow-band filters and provides initial estimate of structure parameters for optimization design of PhC bandpass filters. By fine adjusting the structure parameters such as the radius of the coupling rod, dielectric rod, and perturbing rod, the filter characteristics are studied by using the finite difference time domain method.