Spoof surface plasmon polaritions (SSPPs) have attracted much attention in recent years. Here, we propose compact rejection filters through the adjunction of ultrathin metallic spiral disks near a planar spoof SPP waveguide. The spoof SPP modes can arouse electric dipole localized surface plasmons (LSPs) modes in the ultrathin metallic spiral disks, leading to strong resonances stopping the SPP transmission. Schemes are presented to design single-frequency rejection filters and broad band-stop filters. Numerical simulations demonstrate the isolation can be less than −15dB, and even reach to −30dB, which show the outstanding filtering abilities of this kind filter.
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