Metallic Photonic Crystal Structure with Air-Gap and Its Applications in Resonator and Filter Design

This paper presents a modified M-PhC structure with an air-gap layer inserted between the top metal plate and the metallic cylinder post array. The bandgap structures are calculated and the results show that 1) with the air-gap comes a new propagating mode within DC ~ cutoff frequency. 2) the bandgap structure can be controlled by the height of air-gap. To demonstrate its applications in high frequency regime, firstly, a line-defect transmission line is realized by taking a line of posts away from the post-array. Moreover, point-defect-resonators (PDRs) are implemented by removing one or several posts from the array. Finally, an example BPF is designed using the proposed M-PhC PDRs.