(color online) (a) Sketching of the silver Möbius strip. Here the material is silver. R = 0.8 μm, h = 0.4 μm and t = 0.2 μm. (b) Schematic of the Möbius-strip-type plasmonic cavity. The geometry is a silver Möbius strip sandwiched between dielectric layers. The thickness of dielectric layer d = 0.2 μm. “A” and “B” refer to the cross sections at 20 nm above the silver strip and 20 nm below respectively. (c) Right view of the cavity presents another perspective of the relative position of sections “A” and “B”.