Wideband THz Absorber: By Merging the Resonance of Dielectric Cavity and Graphite Disk Resonator

A graphite/dielectric cavity resonator-based absorber is numerically analyzed and implemented with wideband absorption. A graphite disk resonator is inserted in the low permittivity dielectric THz cavity resonator for the generation of multiple modes. The modes generated in dielectric cavity are merged with the resonating mode of graphite disk resonator for achieving the wideband absorption. The proposed absorber provides the frequency bandwidth of 129.34% (0.65 - 3.03 THz) for absorption >90%. The utilization of symmetrical geometry makes the absorber insensitive to polarization angle (φ) of the incident wave. Also, its performance remains stable over a wide incident angle (θ) covering the range 0° <; 8<; 50°. The operation and response of the proposed absorber is verified by implementing an equivalent circuit model. The proposed absorber can be utilized as sensor for THz medium sensing and imaging applications. A narrowband absorber can also be implemented using the proposed technique which can be utilized in sensing applications of micro scale objects. In addition, the proposed research work provides a technique for the implementation of a metal-free compact structure which can be useful in future micro/nanoscale systems.