Extremely anisotropic boundary conditions and their optical applications



[1] Following the idea of realizing an extremely anisotropic scatterer by combining positive and negative permittivity materials in a composite sphere, we discuss here some of the features and potential applications of extreme boundary conditions in optics. We analyze the scattering features and surface boundaries of an isolated sphere composed of two hemispheres with oppositely signed real parts of permittivity, whose local surface impedance can vary homogeneously from zero to infinity upon a simple 90 degree rotation of the impinging electric polarization, and we theoretically explore how combinations of these particles and other related geometries may tailor and boost the optical radiation of localized sources, e.g., quantum dots and molecular emitters.