Experimental Demonstration of Low‐Energy First‐Order Hybridized Plasmon Resonances in Origami Metashells

Abstract Metallic nanoshells have emerged as promising optical cavities to steer hybridized plasmonic resonances that show the high spectral tunability and a large surface area of localized fields. Despite various optical and photochemical applications, plasmonic resonances in shells have rarely been explored at low frequencies due to a nonlinear increase in particle size and a rapid degeneration in field localization. Here, this work reports the experimental realization of hybridized plasmon resonances in origami metashells that can be excited by low‐energy photons ≈7 GHz, corresponding to a level below 10⁻⁴ eV. Metasurfaces built of interconnected meshes act as thin Drude metallic films that support symmetric spoof surface plasmons. Rigid folding of the metasurface leads to diverse 3D hollow cavities that exhibit strong plasmonic responses, large surface areas, and low relative densities. Experimental measurements demonstrate three typical behaviors in Drude metallic shells: shielding to quasi‐static fields, strong scattering at first‐order hybridized plasmon resonances, and transparency to high frequency radiation. The relative density is remarkably reduced owing to the void cavity enabled by 3D folding, and an extra degree of freedom in anisotropic load capacity is provided by customizing crease patterns. These results open a door for extremely low‐energy plasmons with low‐density mechanics.