Spoof Surface Plasmon Polariton Waveguide With Switchable Notched Band

A coplanar waveguide (CPW) based spoof surface plasmon polariton (SSPP) waveguide with strong field confinement is proposed, which has a low-pass filtering response. Then, two half-wavelength slot resonators are loaded on both sides of the SSPP waveguide to introduce a notch in the passband. Meanwhile, the SSPP waveguide with two ring slot resonators is simulated, whose results are consistent with the SSPP low-pass filter. Finally, two PIN diodes are bridged across the slits of the two resonators to realize the dynamic switchability of the notch. The waveguide functions as a notch filter when the diodes are in on-state, and a low-pass filter when the diodes are in off-state. To verify the feasibility of the design, a SSPP waveguide example is fabricated and measured, where the simulated and measured results are in reasonably good agreement.