Tunable bandstop filter using spoof surface plasmon polaritons for terahertz applications

Abstract

This paper presents the design and analysis of a spoof surface plasmon polaritons (SSPP)-based bandwidth tunable bandstop filter (BSF) operating at 0.26 THz frequency. The proposed filter is comprised of SSPP T-shape resonators which are coupled to the spoof transmission line. Odd and even mode analysis is carried out for the proposed design, and using Co-EM simulation, it is shown that the designed band stop filter is capable of offering tunable bandwidth at THz frequency using a variable capacitor. In order to experimentally validate the proposed approach, design studies are carried out at microwave frequencies and the BSF is developed on a Rogers R4003C substrate of thickness 1.524 mm. The proposed filter designs have a 3 dB bandwidth tunability of 3 GHz (0.038–0.041 THz) and 50 MHz (0.55–0.60 GHz) in the THz and microwave frequency regimes, respectively. The proposed terahertz filter has the potential to be used as an ultra-compact BSF in future applications of photonic integrated circuits in terahertz imaging.