Dielectric-Metal Nanoshell Plasmonic Metamaterial for Filtering and Protection

Abstract

Metamaterials technology shows unique opportunities for “engineering” refractive indices that previously were not accessible and for gaining control over the spatial refractive index classification. In this paper, different dielectric materials (oil, wood) nanoshell with an outer radius of 25 nm and an inner radius of a core 20 nm has been considered. The simulation showed that this structure has both negative epsilon and (negative) mu along the visible frequency range for the dielectric materials (oil, wood), leading to a negative refractive index; so this structure can be considered as a double negative metamaterial. A silver-coated oil shell has a high transmission of orange color which could be used as a filter at this range, while at the same time it has a good absorption of violet color. Nanoshell structures show that they enhance local EM fields in specific regions near their surfaces at specific wavelengths of light, controlled by the geometry of the nanostructure. This study could be used for filtering at specific frequency ranges of visible light. Further studies were done to invent cloaking devices, and other areas in microwave range coating methodologies could be used in the future to protect some of the antiquities outside enclosed museums. The combination of wood and oil dielectric materials—and with consideration of a variation in the radius of the core (wood in this case)—showed an almost unified transmission of the waves.