Coated nano particles for optical metamaterials and nano-photonic applications.

摘要

The optical properties of a concentric nanometer-sized spherical shell comprised of an (active) 3-level gain medium core and a surrounding plasmonic metal shell are investigated. Current research in optical metamaterials has demonstrated that including lossless plasmonic materials to achieve a negative permittivity in a nano-sized coated spherical particle can lead to novel optical properties such as resonant scattering as well as transparency or invisibility. However, in practice, plasmonic materials have high losses at optical frequencies. It will be demonstrated that a properly designed passive optical spherical core impregnated with a gain medium and coated with a concentric spherical plasmonic nano-shell will have a "super resonant" (SR) lasing state. The operating characteristics of this coated nano-particle (CNP) laser have been obtained numerically for a variety of configurations and will be reported here. Once the optical properties of the isolated active CNP inclusion are established, several examples of optical metamaterials using them as inclusions will be presented and analyzed. In particular, the effective material properties of these optical MTMs will be explored using effective medium theories that are applicable to a variety of inclusion configurations. Two-dimensional (2D) mono-layers of these active CNPs, which form metafilms; three-dimensional (3D) periodic arrays of these active CNPs; and 3D random distributions of these active CNPs will be described. The effective permittivities and refractive indexes of these optical MTMs will be compared and contrasted to those of their active CNP inclusions. In addition to the active MTMs, some examples of nano-photonic applications enabled by the unique properties of these inclusions will also be presented. Specifically metamaterial pigments derived from exploiting the high absorption and low scattering properties of the passive CNP particle will be explored for possible use in color display technology as well as the use of the SR lasing state and localized plasmon resonance of the active CNP for nano-sensing applications.