A three-dimensional lattice of micron-scale coated spheres is shown to have an isotropic negative index of refraction at infrared frequencies. The materials used are entirely non-magnetic. The Mie scattering theory of the constituent spheres is used in the effective medium theory. The physical mechanisms and procedures are presented in the design of a negative effective permeability with solid polaritonic spheres, as well as a negative effective permittivity with solid Drude spheres. It is then shown that a collection of polaritonic spheres coated with a thin layer of Drude material can exhibit a negative index of refraction at infrared frequencies. Comparison with numerical photonic band structure calculations verifies the theory.
A negative effective permeability is shown to exist at infrared frequencies in a three-dimensional collection of polaritonic spheres. This is demonstrated by an effective medium theory which relates the Mie resonances of the constituent spheres to the bulk response of the composite. The derived permittivity and permeability are shown to be isotropic. The results are verified by a comparison with multiple-scattering photonic band calculations. The existence of an anomalous dispersion region with a negative group velocity and the appropriate signs associated with the imaginary parts of the permittivity and permeability are also discussed.
Hybrid-mode waveguides consisting of a metal surface separated from a high index medium by a low index spacer have attracted much interest recently. Power is concentrated in the low index spacer region for this waveguide. Here we investigate the properties of the hybrid mode in detail and numerically demonstrate the possibility of realizing compact waveguide bends using this wave guiding scheme.
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