Plasmonic microcavity formed by the Möbius strip

We propose a Mobius-strip-type plasmonic cavity with a silver Mobius strip sandwiched between dielectric layers. By brief theoretical and simulation analyses, we obtain that the factor of the cavity remains about 40 and the mode volume is ultrasmall (less than 1 ) which is more compact than that of the cylindric cavity. This Mobius-strip-type plasmonic cavity supporting the propagation of surface plasmon polaritons owns some unusual properties such as more effective volume and the spatial separation. More potential applications based on this cavity remain to be explored in future nanophotonics.