Electromagnetics and Photonics Commons^™

Novel Methods For The Time-Dependent Maxwell’S Equations And Their Applications, Sidney Shields

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation investigates three different mathematical models based on the time domain Maxwell's equations using three different numerical methods: a Yee scheme using a non-uniform grid, a nodal discontinuous Galerkin (nDG) method, and a newly developed discontinuous Galerkin method named the weak Galerkin (WG) method. The non-uniform Yee scheme is first applied to an electromagnetic metamaterial model. Stability and superconvergence error results are proved for the method, which are then confirmed through numerical results. Additionally, a numerical simulation of backwards wave propagation through a negative-index metamaterial is given using the presented method. Next, the nDG method is used to simulate …

Rural Broadband Mobile Communications: Spectrum Occupancy And Propagation Modeling In Western Montana, Erin Wiles

Graduate Theses & Non-Theses

Fixed and mobile spectrum monitoring stations were implemented to study the spectrum range from 174 to 1000 MHz in rural and remote locations within the mountains of western Montana, USA. The measurements show that the majority of this spectrum range is underused and suitable for spectrum sharing. This work identifies available channels of 5-MHz bandwidth to test a remote mobile broadband network. Both TV broadcast stations and a cellular base station were modelled to test signal propagation and interference scenarios.

Engineered Nanocomposite Materials For Microwave/Millimeter-Wave Applications Of Fused Deposition Modeling, Juan De Dios Castro

USF Tampa Graduate Theses and Dissertations

A variety of high-permittivity (high-k) and low-loss ceramic-thermoplastic composite materials as fused deposition modeling (FDM) feedstock, based on cyclo-olefin polymer (COP) embedded with sintered ceramic fillers, have been developed and investigated for direct digital manufacturing (DDM) of microwave components. The composites presented in this dissertation use a high-temperature sintering process up to 1500°C to further enhance the dielectric properties of the ceramic fillers. The electromagnetic (EM) properties of these newly developed FDM composites were characterized up to the Ku-band by using the cavity perturbation technique. Several models for prediction of the effective relative dielectric permittivity of composites based …

Block Matching And Wiener Filtering Approach To Optical Turbulence Mitigation And Its Application To Simulated And Real Imagery With Quantitative Error Analysis, Russell C. Hardie, Michael Armand Rucci, Barry K. Karch, Alexander J. Dapore

Electrical and Computer Engineering Faculty Publications

We present a block-matching and Wiener filtering approach to atmospheric turbulence mitigation for long-range imaging of extended scenes. We evaluate the proposed method, along with some benchmark methods, using simulated and real-image sequences. The simulated data are generated with a simulation tool developed by one of the authors. These data provide objective truth and allow for quantitative error analysis. The proposed turbulence mitigation method takes a sequence of short-exposure frames of a static scene and outputs a single restored image. A block-matching registration algorithm is used to provide geometric correction for each of the individual input frames. The registered frames …

Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, Russell C. Hardie, Jonathan D. Power, Daniel A. Lemaster, Douglas R. Droege, Szymon Gladysz, Santasri Bose-Pillai

Electrical and Computer Engineering Faculty Publications

We present a numerical wave propagation method for simulating imaging of an extended scene under anisoplanatic conditions. While isoplanatic simulation is relatively common, few tools are specifically designed for simulating the imaging of extended scenes under anisoplanatic conditions. We provide a complete description of the proposed simulation tool, including the wave propagation method used. Our approach computes an array of point spread functions (PSFs) for a two-dimensional grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. The degradation …

Mode Evolution In Fiber Based Devices For Optical Communication Systems, Bin Huang

Electronic Theses and Dissertations

Space division multiplexing (SDM) is the most promising way of increasing the capacity of a single fiber. To enable the few mode fiber (FMF) or multi-mode fiber (MMF) transmission system, several major challenges have to be overcome. One is the urgent need of ideal mode multiplexer, the second is the perfect amplification for all spatial modes, another one is the modal delay spread (MDS) due to group velocity difference of spatial modes. The main subject of this dissertation is to model, fabricate and characterize the mode multiplexer for FMF transmission. First, we designed a novel resonant mode coupler (structured directional …

Three-Dimensional Beam Scan Using Ferrite-Loaded Circular Waveguide Antenna, Hassan Ali Ragheb, Ahmed Elgarni, Essam Hassan, Eqbal Mitu

Electrical Engineering

Phased or parasitic array antennas with complex feed mechanism are widely used to realize beam scanning. This paper presents a simple magnetized ferrite loaded circular waveguide antenna with three dimensional (3D) scan characteristics. Professional software is used to optimize the dimension and biasing requirement of the antenna. The required magnetizing fields (H 0 ) are tabulated to realize 60° of maximum beam scan in elevation plane for eight different azimuth regions covering 360°. A prototype of the high power waveguide antenna is fabricated to experimentally verify some of the simulated scan characteristics. Using LTCC technique, embedding the biasing coils within …

Development Of Active Microwave Thermography For Structural Health Monitoring, Ali Foudazi

Doctoral Dissertations

"Active Microwave Thermography (AMT) is an integrated nondestructive testing and evaluation (NDT&E) method that incorporates aspects of microwave NDT and thermography techniques. AMT uses a microwave excitation to generate heat and the surface thermal profile of the material or structure under test is subsequently measured using a thermal camera (or IR camera). Utilizing a microwave heat excitation provides advantages over traditional thermal excitations (heat lamps, etc.) including the potential for non-contact, selective and focused heating. During an AMT inspection, two heating mechanisms are possible, referred to as dielectric and induction heating. Dielectric heating occurs as a result of the interaction …

Modal Based Bga Modeling In High-Speed Package, Shuai Jin

Doctoral Dissertations

"In the Section 1, the improved "Root-Omega" method for extracting dielectric properties from fabricated multilayer printed circuit boards is proposed. Based on the electrical properties of fabricated transmission lines, the improved "Root-Omega" method applied to cases with smooth and rough conductors is validated using simulations. Error sensitivity analysis is performed to demonstrate the potential errors in the original "Root-Omega" procedure and the error sensitivity is significantly reduced by the proposed improvements.

In the Section 2, a fast modal-based approach is developed to accurately and efficiently capture the proximity effect. Image theory is also applied in the proposed approach to reduce …

Engineering Of Photo-Rechargeable Energy Storage, Ashim Gurung

Electronic Theses and Dissertations

Solar photovoltaics (PV) is a very promising renewable energy technologies as it is abundant and pollution-free. However, the major drawback of PV power is its intermittency. Integration of batteries with solar modules can reduce overall PV system costs and increase the practicality of PV power. Integration of the photovoltaic cells with supercapacitor storage proved feasibility of combined photovoltaic energy generation and storage but the supercapacitors had low energy storage capacity. Photovoltaic cells with integrated Li-ion batteries as energy storage were demonstrated but had a complex structure due to multiple PV cells; low efficiency due to a mismatch between the PV …

Generating Fast And Accurate Compliance Reports For Various Data Rates, Srinath Penugonda

Masters Theses

"As the demands on the industry data rates have increased there is a need for interoperable interfaces to function flawlessly. Added to this complexity, the number of I/O data lines are also increasing making it more time consuming to design and test. This in general leads to creating of compliance standards to which interfaces must adhere. The goal of this theses is to aid the Signal Integrity Engineers with a better and fast way of rendering a full picture of the interface compliance parameters.

Three different interfaces at various data rates were chosen. They are: 25Gbps Very Short Reach (VSR) …

Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen

Electronic Theses and Dissertations

Several metrics are commonly used to evaluate the performance of display devices. In this dissertation, we analyze three key parameters: fast response time, wide color gamut, and high contrast ratio, which affect the final perceived image quality. Firstly, we investigate how response time affects the motion blur, and then discover the 2-ms rule. With advanced low-viscosity materials, new operation modes, and backlight modulation technique, liquid crystal displays (LCDs) with an unnoticeable image blur can be realized. Its performance is comparable to an impulse-type display, like cathode ray tube (CRT). Next, we propose two novel backlight configurations to improve an LCD's …

Enhanced Ablation By Femtosecond And Nanoseond Pulses, Haley Kerrigan

Electronic Theses and Dissertations

Laser ablation of GaAs by a combination of femtosecond and nanosecond pulses is investigated as a means of enhancing material removal by a femtosecond pulse in the filamentation intensity regime. We demonstrate for the first time increased ablation of GaAs by ultrafast laser pulse plasmas augmented by nanosecond pulse radiation from a secondary laser. Material removal during laser ablation is a complex process that occurs via multiple mechanisms over several timescales. Due to different pulse durations, ablation by femtosecond and nanosecond pulses are dominated by different mechanisms. Ablation can be enhanced by optimally combining a femtosecond and nanosecond pulse in …

Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken

Electronic Theses and Dissertations

Glass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the resulting composite's optical properties including refractive index, transmission, dispersion, and thermo-optic coefficient. Optical property evolution was related to the type and amount of the crystal phases formed, since through control of the local …

Design Of A Hydrogen-Filled Hollow-Core Fiber Raman Laser, Yangyang Qin

Electronic Theses and Dissertations

The purpose of this study is to investigate the design of a Raman fiber laser based on a molecule hydrogen-filled hollow-core fiber with non-touching single ring of capillaries structure. O-hydrogen vibrational frequency shift of 4155 cm-1 and rotational frequency shift of 587 cm-1 were employed to generate Raman scattering from a 1064nm pump source. A thorough exploration was made to show how all Raman fiber laser components made up: gas chamber, hollow-core fibers, windows. The whole process of chamber design, modification and fabrication were demonstrated. Besides, two kinds of anti-resonant hollow-core fibers were studied and tested. The transmission and loss …

Enhancement Of Bandwidth And Laser Deflection Angle Of Acousto-Optic Deflectors By Dynamic Two-Dimensional Refractive Index Modulation, Tiansi Wang

Electronic Theses and Dissertations

Acousto-Optic Deflectors (AODs) are inertialess optical solid state devices that have advantages over conventional mechanically controlled mirror-based deflectors in numerous scientific and industrial applications. These applications include fluorescence microscopy, sensing, variable-focus lens, photolithography and laser materials processing. AODs are currently operated with a single piezoelectric transducer that modulates the refractive index only in one direction. This operating principle limits the performance of AODs to a narrow acoustic bandwidth of the transducer and a small angle of laser deflection governed by the Bragg diffraction. To overcome these two limitations, the operation of AODs with phased array ultrasonic transducers is analyzed in …

Noise, Stability, And Linewidth Performance Of 10-Ghz Optical Frequency Combs Generated From The Nested Cavity Architecture, Kristina Bagnell

Electronic Theses and Dissertations

Optical frequency combs with wide mode spacing and low timing jitter are relied upon for both time domain and frequency domain applications. It has been previously demonstrated that surrounding a low-Q semiconductor laser chip with a long external fiber cavity and inserting a high finesse Fabry–Pérot etalon into this cavity can produce a mode-locked laser with the desired high repetition rate and narrow optical mode linewidths which are of benefit to applications like photonic analog-to-digital conversion and astronomical spectrograph calibration. With this nested cavity architecture, the quality factor of the resonator is effectively determined by the product of the individual …

High Dynamic Range Display Systems, Ruidong Zhu

Electronic Theses and Dissertations

High contrast ratio (CR) enables a display system to faithfully reproduce the real objects. However, achieving high contrast, especially high ambient contrast (ACR), is a challenging task. In this dissertation, two display systems with high CR are discussed: high ACR augmented reality (AR) display and high dynamic range (HDR) display. For an AR display, we improved its ACR by incorporating a tunable transmittance liquid crystal (LC) film. The film has high tunable transmittance range, fast response time, and is fail-safe. To reduce the weight and size of a display system, we proposed a functional reflective polarizer, which can also help …

Harnessing Spatial Intensity Fluctuations For Optical Imaging And Sensing, Milad Akhlaghi Bouzan

Electronic Theses and Dissertations

Properties of light such as amplitude and phase, temporal and spatial coherence, polarization, etc. are abundantly used for sensing and imaging. Regardless of the passive or active nature of the sensing method, optical intensity fluctuations are always present! While these fluctuations are usually regarded as noise, there are situations where one can harness the intensity fluctuations to enhance certain attributes of the sensing procedure. In this thesis, we developed different sensing methodologies that use statistical properties of optical fluctuations for gauging specific information. We examine this concept in the context of three different aspects of computational optical imaging and sensing. …

Electromagnetic Signal Feedback Control For Proximity Detection Systems, Adam K. Smith

Dissertations, Master's Theses and Master's Reports

Coal is the most abundant fossil fuel in the United States and remains an essential source of energy. While more than half of coal production comes from surface mining, nearly twice as many workers are employed by underground operations.

One of the key pieces of equipment used in underground coal mining is the continuous mining machine. These large and powerful machines are operated in confined spaces by remote control. Since 1984, 40 mine workers in the U. S. have been killed when struck or pinned by a continuous mining machine. It is estimated that a majority of these accidents could …