Thesis (M.S.)--Baylor University, 2006. / Includes bibliographical references (p. 80-83).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 90 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 74-76).

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M.Ing. / All-optical networks, although highly promising, have a long way to go before they will replace existing optical networks such as SONET. The development of the all-optical networks relies on the components market to supply reliable and integrated components to facilitate filtering and management in the optical domain. Planar lightwave circuits (PLCs) and photonic integrated circuits (PICs) provide the answer, with the potential of integrating various functions on a single substrate. The design of lightwave circuits starts with the design and testing of a waveguide. Once this manufactured waveguide exhibits the right characteristics and is proved to be reproducible, it can be used in the design of components. In industry, this design is done by utilizing the beam propagation method (BPM). In order to design useful circuits, the simulation results of simple structures should be compared with experimental results to check their sensitivity to certain parameters. Once the relationship between manufactured and simulated components is understood, the design of components can commence with confidence. In this thesis, BPM simulation results are compared with a reported manufactured waveguide, and then used to design various components used for filtering purposes in dense wavelength division multiplexed (DWDM) systems. Designs for the couplers that serve as building blocks for the filters are discussed, and a novel technique of design downscaling is presented for bi-directional couplers. The filters under investigation are all moving average filters, namely Mach-Zehnder lattice filters, and the highly integrated arrayed waveguide gratings (AWGs). Applications for both these filters are presented.

An analysis of a class of corrugated structures is given for the purpose of determining the extent to which slot evanescent modes affect the shape of the dispersion curve. The analysis also permits a critical examination of a previous prediction of conditional confluence in this structure. An existing analysis of the cylindrical slot-coupled cavity chain is presented and then extended to include the effect of higher normal modes. The accuracy of this extension is examined experimentally. A discussion of zero-mode conditional confluence based upon this theory is presented. Experimental confirmation of zero-mode confluence is made. The possibility of achieving conditional confluence in the centipede structure and the reversed-loop-coupled cavity chain is discussed. The discussion is based upon an analysis by Bevensee. Two confluence tests are presented to complement the existing one. Finally, a discussion on the usefulness of auto-confluent structures for accelerator applications is presented. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Accurate measurements of the propagation coefficient of the HE₁₁ mode on polythene-tube waveguides in air and surrounded by a polyfoam shield are reported. These were carried out at X-band frequencies using a cavity-resonance method. The results obtained confirm previous theoretical predictions although there is an element of uncertainty concerning the exact dielectric properties of the commercial grade polythene tubes used. The measurements also yielded the phase coefficient of the HE₁₁ mode which was confirmed by measurement of the radial decay of the electric field outside the tube. Enclosing the dielectric-tube in a low-density, low-loss polyfoam shield resulted in only a slight degradation of the attenuation characteristics of the waveguides. Measurements of the phase characteristics of the higher order TE₀₁ and TM₀₁ modes on the tube at frequencies close to cutoff are also reported. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Neural transduction is the process by which neurons convert externally applied electrical energy into stable, propagating voltage pulses. Given some stimulus waveform with particular parameters such as duration, phase delay, etc., there is a minimum stimulus amplitude required in order for transduction of the waveform to result in an active neural response. The minimum amplitude for excitation, the threshold amplitude, is a strong function of many variables including stimulus waveshape, frequency and duration. This study reveals some details of the threshold characteristics of the Frankenhaeuser-Huxley (FH) model of myelinated nerve. These threshold transduction characteristics are studied with the aid of phase-space analysis, and are used to produce a model of neural excitation which is clinically applicable to human nerve. The full FH system of equations is used to predict threshold behaviour for in-vivo human nerve, and the predictions are shown to be in good agreement with clinically obtained threshold data. The study concludes by examining some of the additions to the FH model which would be necessary to model the accumulation of extra-nodal potassium ions. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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