Characterization of Surface-Plasmon Polaritons and Electromagnetic Waveguides With Positive, Negative and Near-Zero Permittivity and Permeability
Creators: name: Sang-Nourpour, Nafiseh
Publisher: name: Graduate Studies
Year: 2017
Subjects: subject: Education--Physical
subject: Surface-Plasmon Polariton
subject: Electromagnetic Waveguide
subject: Lossy Planar Single-Interface
subject: Lossy Curved Single-Interface
subject: Characterization
subject: Metamaterial
subject: Robustness Analysis
subject: Conformal Mapping
subject: Duality of Electromagnetism

description: This thesis reports advances in characterization of electromagnetic waveguides and surface-plasmon polaritons. I advance the applications of electromagnetic waveguides through investigations of electromagnetic duality in waveguides and the tunability of particular waveguide modes. Moreover, an accurate and precise procedure is devised for characterizing surface-plasmon polaritons at lossy planar and curved interfaces. The explanations of each step in this work are summarized as follows. A description of waveguides that respects the duality of electromagnetism, namely the symmetry of the equations arising through the inclusion of magnetic monopoles in addition to electrons, is presented in the thesis. To ensure manifest electromagnetic duality in waveguides, I employ generic electromagnetic susceptibilities that are dual in both electric charges and magnetic monopoles using the generalized Drude-Lorentz model. Our description accommodates exotic media, such as double-negative, near-zero and zero-index materials. I consider metamaterials and metamaterial waveguides, as well as metal waveguides, as examples of waveguides constructed of electromagnetic materials. In particular, in the slab and cylindrical waveguides, exchanging electric and magnetic material properties leads to the exchange of transverse magnetic and transverse electric modes and dispersion equations, which suggests a good test of the potential duality of waveguides. Our advances establish an intuitive microscopic-level understanding of the electromagnetic duality in waveguides and its applications. The properties of metamaterials are then employed to tailor the modes of metamaterial-dielectric waveguides operating at optical frequencies. I survey the effects of 3D isotropic metamaterial structural parameters on the refractive index of metamaterials and on the modes in slab metamaterial-dielectric waveguides. Hybrid modes refer to hybrid ordinary-surface-plasmon polariton modes in the waveguide structures. I investigate how robust metamaterials are to fluctuations in their structural parameters; specifically, the effects of Gaussian errors are examined on the metamaterials EM behaviour. Our survey enables us to determine the allowable fluctuation limits and from this to identify appropriate unit-cell structure for further applications of metamaterials in waveguides technologies. I also characterize surface-plasmon polaritons at lossy planar interfaces between one dispersive and one nondispersive linear isotropic homogeneous media, i.e., materials or metamaterials. Specifically, Maxwell's equations are solved to obtain strict bounds for the permittivity and permeability of these media such that satisfying these bounds implies surface-plasmon polaritons successfully propagate at the interface, and violation of the bounds signifies propagation is impeded, i.e., the field delocalizes from the surface into the bulk. Our characterization of surface-plasmon polaritons is valuable for checking viability of a proposed application, and, as an example, our method is employed to falsify a previous prediction that surface-plasmon propagation through a surface of a double-negative refractive index medium occurs for any permittivity and permeability; instead our results show that propagation can occur only for certain medium parameters. Finally, a theoretical study of surface-plasmon polaritons propagation along lossy curved interfaces is presented here. Specifically, conformal transformation is employed to map the curved interface between one lossy dispersive and one nondispersive linear isotropic homogeneous material to a planar interface between inhomogeneous materials. My characterization of surface-plasmon polaritons is valuable for checking the viability of a proposed application.