Analysis of scattering of plane electromagnetic waves by stratified spheres of radially uniaxial anisotropic materials

Abstract

The aim of this thesis is to characterize electrically-small spheres with radial anisotropy and stratified structure for either minimizing or maximizing scattering by plane waves based on the extended Mie scattering model. This theory is applicable to the case of single-layer spheres as well. The original contributions of the thesis are twofold. First, for the case of a single-layer sphere with radial anisotropy, a transparency condition comprising of radial and tangential permittivity is analytically established. As such, particles with carefully engineered radial anisotropy are transparent without using any coating and are ideal for applications with space constraint and stringent transparency criteria. Second, for the case of a coated sphere with radial anisotropy, a resonance condition is analytically derived. The derived condition provides a guideline for choosing material and structural parameters in the design of plasmon-resonant particles at given frequencies of interest for applications in sensing. For both cases, the effective permittivity of the scatterers of interest is derived in comparison with pertinent expressions of scattering coefficients for isotropic spheres. Physical insights are also provided. In addition, full-wave numerical analysis is presented to validate the proposed conditions.