Whispering-Gallery Resonators for Highly Integrated Plasmonic THz Circuits

Whispering-gallery resonators based on spoof plasmonic rings are presented. The resonators exhibit exceptionally high quality factors for THz metasurfaces (in excess of 240). As the resonator is coupled to two waveguides, it can serve as narrowband band-stop and band-pass filter in an integrated plasmonic circuit. The complicated mode structure shows frequency comb-like behaviour.