Multiband localized spoof plasmons in closed textured cavities.

In this work, we explore the existence of multiband localized spoof plasmons (LSPs) in closed textured cavities with multiple groove depths. It is interesting to note that the spoof LSPs in each band resemble those generated by the textured 2D cavities of the same periodicity with the corresponding single groove depth, and the field distributions and confinement characteristics of the plasmon-like modes in such a corrugated cavity are different from the conventional cavity. Hence, these multiple resonance band structures can find potential applications in the microwave and terahertz frequencies.