No description available.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 103-109).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 102-106).

The Rayleigh-Taylor instability of a water-air interface was investigated using electrical and photographic methods. An apparatus is described which accelerates a rectangular tank of water downwards and produces reproducible instabilities from a pure sinusoidal standing surface water wave of known phase and amplitude. The electrical measurements revealed that in addition to the bulk motion, films of water are produced on the walls of the water tank. The existence of these and other features of the instability are substantiated by photographs of the various instabilities that were produced. The electrical measurements led to a new scaling law for the phenomenon of climbing fluid films at accelerations greater than gravity. Several linear devices were also developed for measuring the amplitudes of surface water waves. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The first part of this thesis is concerned with theoretical and experimental investigations of step discontinuities on a planar surface waveguide. An approximate theoretical solution to the unbounded discontinuity problem is obtained by bounding the open structure with perfect conductors, since there is a direct relationship between the mode spectra of the two configurations. Mode-matching is used to solve the bounded case. The method is "tested" on four discontinuity configurations considered by other workers. Good agreement with the previous results is obtained in all cases except one for which the original results are shown to be inaccurate. The experimental investigation is carried out on a dielectric coated conductor surface waveguide, supporting the first TM mode, at a frequency of 30 GHz. Standing wave measurements are obtained using a X/2 dipole oriented along the longitudinal component of electric field. The parameters of interest are the magnitude and the phase of the reflection coefficient. The experimental results confirm those obtained theoretically. The theoretical and experimental techniques are later applied in an investigation of a cascaded step discontinuity configuration. The theoretical approach involves the use of wave transmission matrices. Experimental results for the magnitude of the reflection coefficient are found to be in reasonable agreement with theory. The second part of this work describes a theoretical and experimental study of dielectric waveguides, of circular cross-sections, perturbed by axial slots. In particular, the normalized propagation coefficient of the dominant modes with each polarization is determined analytically using a standard perturbation technique and experimentally using an open resonant cavity. The perturbation results give quite a good indication of the trends observed experimentally. It is found that there is an optimum size of the perturbation which gives the maximum separation between the normalized propagation coefficients of the two polarizations. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

Thesis advisor: Willie J. Padilla / The field of metamaterials (MMs) has garnered a great deal of attention ever since the experimental demonstration of negative refractive indexes. Such an exotic response stemmed from the engineering capability of MMs, as they can obtain almost any optical responses at any given frequency by carefully structuring the geometries. There are countless examples where MMs have posed promising results in tailoring free space radiation. However, their usage beyond this common platform is far less explored. For examples, surface electromagnetic waves, which offer great potentials for future device applications, could be an intriguing place for the further development of metamateirals. In this dissertation, we study various MM configurations where the interplay between surface waves and metamaterials has a significant impact on the device performance. Firstly, Chapter 1 introduces some fundamental concepts of metamaterials and surface electromagnetic waves, and outline the fabrication, experiments, and characterization details. In Chapter 2, we investigate whether the effective optical parameters of MMs have the exact physical meaning as those of natural substances. Two types of MM resonators are studied, and we found the thickness of the host matrix plays a crucial role in such a homogenization process. Next, we present a computational and experimental study of MMs in conjunction with a novel gigahertz/terahertz transmission line, in Chapter 3. By optimizing the coupling between the MMs and the signal, information can be encoded. Chapter 4 presents a study of designing an extremely subwavelength magnetic MM. By maximizing the effective inductance and capacitance of the structure, the final geometry obtains a strong magnetic resonance with the size of merely λₒ/2000, where λₒ is the resonant wavelength. A novel time-domain spectroscopic method is also proposed to determine the frequency-dependent permeability of the samples. In Chapter 5, we characterize two hidden channels of MM perfect absorbers : scattering and generation of surface electromagnetic waves. In particular, we unveil lossy surface waves are generated during the process resulting in an enhancement of angular absorbance. The study provides a new insight to the working principle of MMAs. In Chapter 6, we investigate complementary MM structures that exhibit strong extraordinary optical transmission with higher transmission efficiency. We discover the origin of the fundamental mode is irrelevant to the Bloch modes. Lastly, we summarize all achievements and give an outlook in Chapter 7. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

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Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 112-114).

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 98-100).