Fig. 3
From: Subwavelength core/shell cylindrical nanostructures for novel plasmonic and metamaterial devices
(a is adapted from [28], b, c are adapted from [30], and d–f are adapted from [32])
Subwavelength cylindrical metasurface and metamaterial shell structures for invisibility cloaking. a Scattering width spectra (TM-polarized light) of an infinitely long dielectric cylinder with (red solid line) and without (black dashed line) a metasurface mantle cloak. Inset: schematic illustration of the metasurface mantle cloaked device. The dielectric core has an electric permittivity of 10 and the diameter of λ/4, where λ is the invisibility wavelength. The metasurface comprises an array of square metallic rings with a thickness of λ/400. b Concept of a broadband metasurface mantle cloak on an infinite dielectric cylinder featuring an array of ultrathin curved metal patches loaded with non-Foster elements. c Normalized scattering width spectra of a dielectric core covered with various metasurface mantle cloaks. d Schematic illustration of a coaxial metal/dielectric multilayered metamaterial nanotube. The nanotube has an air core (diameter = D) and a metamaterial shell (thickness = T) comprising multiple layers of alternating Ag/TiO2 films. e Scattering efficiency spectra of a layered nanotube structure with a core diameter of 100 nm and a shell thickness of 60 nm for TE- (black line, top inset) and TM- (red line, bottom inset) polarized light. The thicknesses of both individual Ag and TiO2 layers are set to 10 nm. The invisible region is indicated by a shaded gray area. f Snapshot of the normalized electric field intensity distribution and time-averaged Poynting vector power flows (gray lines and arrows) near the metal/dielectric layered nanotube at the invisible wavelength of ~ 450 nm