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Electromagnetics and Photonics

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Full-Text Articles in Engineering

Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo Dec 2019

Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo

Theses and Dissertations

Noble metal nanoparticles and two-dimensional (2D) transition metal dichalcogenide (TMD) crystals offer unique optical and electronic properties that include strong exciton binding, spin-orbital coupling, and localized surface plasmon resonance. Controlling these properties at high spatiotemporal resolution can support emerging optoelectronic coupling and enhanced optical features. Excitation dynamics of these optical properties on physicochemically bonded mono- and few-layer TMD crystals with metal nanocrystals and two overlapping spherical metal nanocrystals were examined by concurrently (i) DDA simulations and (ii) far-field optical transmission UV-vis spectroscopic measurements. Initially, a novel and scalable method to unsettle van der Waals bonds in bulk TMDs to prepare ...


Nondestructive Electromagnetic Characterization Of Perfect-Electric-Conductor-Backed Uniaxial Materials, Adam L. Brooks Sep 2019

Nondestructive Electromagnetic Characterization Of Perfect-Electric-Conductor-Backed Uniaxial Materials, Adam L. Brooks

Theses and Dissertations

As the use of anisotropic materials in electromagnetic applications continues to proliferate, it becomes increasingly important to develop non-destructive evaluation methods for those materials in their installed configuration. In many applications, these materials are permanently affixed onto conducting bodies to reduce unwanted reflections, making it impossible to collect S21 or S12 transmission measurements as used in many techniques based on the well-known Nicolson-Ross-Weir algorithm. It also makes it impractical to reorient the sample to collect orthogonal measurements aligned with the optical axes of the anisotropic material. The goal of this research is to develop a two-reflection coefficient measurement ...


Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace Aug 2019

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace

Theses and Dissertations

Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre ...


Triple-Junction Solar Cells : In Parallel., Levi C Mays Aug 2019

Triple-Junction Solar Cells : In Parallel., Levi C Mays

Electronic Theses and Dissertations

This paper looks into the current inefficiency of solar cells and attempts a few alternative solar cell structures in order to provide a more effective source of renewable energy. Currently, multi-junction solar cells are being developed to capture the sun’s light more efficiently. One of the ideas in this paper is to add a window to see if the addition of such a layer into a junction will increase the voltage while maintaining nearly the same current output. Central to this paper is the rearranging of the conducting layers of the multi-junction cell so that the junctions can be ...


Polarization Properties Of Airy And Ince-Gaussian Laser Beams, Sean Michael Nomoto Aug 2019

Polarization Properties Of Airy And Ince-Gaussian Laser Beams, Sean Michael Nomoto

Theses and Dissertations

The description of polarization states of laser light as linear, circular polarization within the paraxial scalar wave approximation is adequate for most applications. However, this description falls short when considering laser light as an electromagnetic wave satisfying Maxwell's equations. An electric field with a constant unit vector for direction of the field and a space dependent complex scalar amplitude in the paraxial wave approximation does not satisfy Maxwell equations which, in general, requires all three Cartesian components of electric and magnetic fields associated for a nonzero laser beam to be nonzero.

Physical observation of passing a linearly polarized laser ...


Growth Of Indium Nitride Quantum Dots By Molecular Beam Epitaxy, Steven P. Minor Aug 2019

Growth Of Indium Nitride Quantum Dots By Molecular Beam Epitaxy, Steven P. Minor

Theses and Dissertations

Over the last decade, the evolution of the global consciousness in response to decreasing environmental conditions from global warming and pollution has led to an outcry for finding new alternative/clean methods for harvesting energy and determining ways to minimize energy consumption. III-nitride materials are of interest for optoelectronic and electronic device applications such as high efficiency solar cells, solid state lighting (LEDs), and blue laser (Blu-ray Technology) applications. The wide range of direct band gaps covered by its alloys (0.7eV-6.2eV) best illustrates the versatility of III-nitride materials. This wide range has enabled applications extending from the ultraviolet ...


The Design Of Passive Networks With Full-Wave Component Models, Eric Valentino Jun 2019

The Design Of Passive Networks With Full-Wave Component Models, Eric Valentino

Graduate Theses and Dissertations

In this thesis, the design of passive networks with the aid of full-wave simulation software and geometry-based models of lumped elements is investigated. This is done by examining the results of a number of simulation examples, as well as measured data from manufactured designs to compare against simulated equivalents. One such example is a chip antenna evaluation board design, in which the PCB, antenna, matching components and connector are all modeled. When measured, the simulation agreed with the board’s best matched frequency of 5.5 GHz to within 20 MHz. In another, a new antenna layout is generated from ...


Dc-Dc Converter For Electric Vehicle, Jason Y. Zhou, Nicholas James Mah Jun 2019

Dc-Dc Converter For Electric Vehicle, Jason Y. Zhou, Nicholas James Mah

Electrical Engineering

In this work, a DC-DC converter is designed for an electric vehicle. The DC-DC converter is designed to provide 500W with a 200-400V input and a 12-15V adjustable output. Electric vehicle sales are beginning to increase in popularity and the need for DC-DC converters to siphon power from the tractive system is not yet fully satisfied, especially for single-seater class vehicles. Additionally, improving performance in efficiency without sacrificing wide input voltage range can benefit future DC-DC converter designs. In the end, a forward active clamp DC-DC converter is designed and tested. Additionally, spreadsheet calculators, LTSpice simulations, and Matlab scripts were ...


Designing A Simulator For An Electrically-Pumped Organic Laser Diode, Robert Hulbert Jun 2019

Designing A Simulator For An Electrically-Pumped Organic Laser Diode, Robert Hulbert

Master's Theses and Project Reports

Organic semiconductors provide an alternative set of basis materials to fabricate electronic devices like PN Junctions, LEDs, and FETs. These materials have several benefits over traditional inorganic semiconductors including their mechanical flexibility, reliance on renewable resources, and inexpensive large-scale manufacturability. Despite the contemporary device implementations with organic semiconductors, a solid-state electrically-pumped organic laser diode does not exist. However, organically-based lasers do exist by utilizing the organic material strictly for optical gain. The challenge occurs when charge carriers appear in the organic material. The charge carriers must reach a concentration such that population inversion occurs producing optical gain. However, between the ...


High Frequency Constraints On The Layout Of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures, Jonathan Hajime Itokazu May 2019

High Frequency Constraints On The Layout Of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures, Jonathan Hajime Itokazu

Theses and Dissertations

Since its integration into power electronic converters, the value proposition of wide band

gap semiconductors has yet to be holistically realized due to the high frequency effects associated with increased switching speeds. The United States Navy’s Smart Ship System

Design (S3D) platform enables the investigation of wide band gap-based devices in shipboard Medium Voltage Direct Current (MVDC) Integrated Power and Energy Systems

(IPES) through the use of metaheuristic model-based scaling laws. These physics-based

scaling laws are produced from a virtual prototyping approach which takes into account the

discrete building blocks associated with multi-cell based power conversion and distribution

equipment ...


High Frequency Constraints On The Layout Of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures, Jonathan Hajime Itokazu May 2019

High Frequency Constraints On The Layout Of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures, Jonathan Hajime Itokazu

Theses and Dissertations

Since its integration into power electronic converters, the value proposition of wide band

gap semiconductors has yet to be holistically realized due to the high frequency effects associated with increased switching speeds. The United States Navy’s Smart Ship System

Design (S3D) platform enables the investigation of wide band gap-based devices in shipboard Medium Voltage Direct Current (MVDC) Integrated Power and Energy Systems

(IPES) through the use of metaheuristic model-based scaling laws. These physics-based

scaling laws are produced from a virtual prototyping approach which takes into account the

discrete building blocks associated with multi-cell based power conversion and distribution

equipment ...


Research Of Electro-Optical Effect In Metal Halide Perovskites By Fabry-Perot Interometer Method, Hanxiang Yin May 2019

Research Of Electro-Optical Effect In Metal Halide Perovskites By Fabry-Perot Interometer Method, Hanxiang Yin

Engineering and Applied Science Theses & Dissertations

Perovskites have been investigated a lot by present and reported with outstanding optoelectronic properties. However, so far there is no publications about another important property, the electro-optical (EO) effect which is related to important applications in photolithography. This thesis is mainly mean to calculate the EO constants of one kind of organic perovskite material, CH3NH3PbI3, which has been reported to have good capability of forming film by spin-coating, through the way of putting the film of CH3NH3PbI3 between two layers of metal mirrors to build a Fabry-Perot interferometer and characterizing ...


Characterization Of Hydride Vapor Phase Epitaxy Grown Gan Substrates For Future Iii-Nitride Growth, Alaa Ahmad Kawagy May 2019

Characterization Of Hydride Vapor Phase Epitaxy Grown Gan Substrates For Future Iii-Nitride Growth, Alaa Ahmad Kawagy

Theses and Dissertations

The aim of this research is to investigate and characterize the quality of commercially obtained gallium nitride (GaN) on sapphire substrates that have been grown using hydride vapor phase epitaxy (HVPE). GaN substrates are the best choice for optoelectronic applications because of their physical and electrical properties. Even though HVPE GaN substrates are available at low-cost and create the opportunities for growth and production, these substrates suffer from large macro-scale defects on the surface of the substrate.

In this research, four GaN on sapphire substrates were investigated in order to characterize the surface defects and, subsequently, understand their influence on ...


Investigation Of Critical Technologies Of Chemical Vapor Deposition For Advanced (Si)Gesn Materials, Joshua Matthew Grant May 2019

Investigation Of Critical Technologies Of Chemical Vapor Deposition For Advanced (Si)Gesn Materials, Joshua Matthew Grant

Theses and Dissertations

The development of new materials for efficient optoelectronic devices from Group IV elements is the heart of Group IV photonics. This has direct ties to modern technology as the foundation for the electronics industry is silicon. This has driven the development of silicon-based optoelectronics using these other Group IV materials as silicon is a poor optical material due to its indirect band gap when compared to the III-V semiconductors that are used by most of the optoelectronics industry. While efforts have been made to integrate III-V materials onto silicon substrates, the incompatibility with the complementary metal oxide semiconductor process has ...


Experimental And Computational Study On Magnetic Nanowires Of Layered Titanates, Caleb Layne Heath May 2019

Experimental And Computational Study On Magnetic Nanowires Of Layered Titanates, Caleb Layne Heath

Theses and Dissertations

The intricate nanostructures of layered titanates are unique among nanomaterials due to their easy and inexpensive syntheses. These nanomaterials have been proven valuable for use in industries as varied as energy, water treatment, and healthcare, and can be produced at industrial scales using already existent equipment. They have complex morphology, and surface structure well suited to chemical modification and doping. However, there is a longstanding debate on their lattice structure after the doping. There is a long-unmet need to understand, using both experimental and simulation methods, how dopants alter the clay-like layered crystal structure and associated physical and chemical properties ...


Optical Response Analysis Of Thz Photoconductive Antenna Using Comsol Multiphysics, Jose Isaac Santos Batista May 2019

Optical Response Analysis Of Thz Photoconductive Antenna Using Comsol Multiphysics, Jose Isaac Santos Batista

Electrical Engineering Undergraduate Honors Theses

A THz photoconductive antenna consists of antenna pads laid over a photoconductive substrate. These types of antennas are excited through the application of an optical pump (laser), which generates carriers inside the semiconductor. The acceleration and recombination of these carriers produce photocurrent that excites the antenna and generates THz pulse. This thesis focuses on analyzing the optical response of a photoconductive antenna, which consist of the interaction of the incident electric field of a laser pump with the radiating device. It develops the amplitude modulation process of a plane wave of light into a laser pump. It also takes into ...


Non-Invasive Beam Monitoring With Harmonic Cavities, Brock F. Roberts Apr 2019

Non-Invasive Beam Monitoring With Harmonic Cavities, Brock F. Roberts

Electrical and Computer Engineering ETDs

NON INVASIVE BEAM MONITORING WITH HARMONIC CAVITIES

by

Brock Franklin Roberts

B.S PHYSICS, UNIVERSITY OF CALIFORNIA DAVIS, 1992

DOCTOR OF PHILOSOPHY IN ELECTRICAL ENGINEERING

UNIVERSITY OF NEW MEXICO, 2019

ABSTRACT

A cavity designed to have multiple harmonic TM0N0 modes can be used to accurately measure the longitudinal profile of a bunched charged particle beam passing through its bore, non-invasively, and in real time.

Multi-harmonic TM0N0 cavities were designed, constructed, and beamline tested in a variety of experiments at the Thomas Jefferson National Accelerator Facility (TJNAF or Jlab). Measurements with a sampling oscilloscope provided signals that resemble the profile of ...


Design And Performance Evaluation Of Linear And Axial-Flux Magnetic Gears, Mojtaba Bahrami Kouhshahi Apr 2019

Design And Performance Evaluation Of Linear And Axial-Flux Magnetic Gears, Mojtaba Bahrami Kouhshahi

Dissertations and Theses

The conversion from low speed to high speed and vice versa in various forms, including rotary and linear motion, is a requirement for a wide range of applications. For example, wind power generation requires a conversion of low speed rotation of turbine blades to high speed generator rotation, and ocean wave power generation is achievable by conversion of low speed linear motion to either high speed rotation or high speed linear motion. Mechanical gearboxes, hydraulic and pneumatic actuators are commonly used to achieve these conversions. However, these systems suffer from reliability issues, high maintenance requirements, noise, and lack of overload ...


Displacement Damage Effects In Gesn Light Emitting Diodes, Kevin K. Choe Mar 2019

Displacement Damage Effects In Gesn Light Emitting Diodes, Kevin K. Choe

Theses and Dissertations

Potential future use on Earth-orbiting satellites calls for investigation into the suitability of GeSn based photonic devices in high energy proton environments. The electroluminescence (EL) intensity of Ge1-xSnx (x = 0, 0.02, 0.069, and 0.094) light emitting diodes was measured before and after irradiation by 2 MeV protons at relatively high fluence levels. The results showed that GeSn devices with higher Sn content were up to 10 times more resistant against proton displacement damage than the pure Ge (x = 0) devices. As Sn concentration increased, the band gap decreased, and V-P hole trap energy level moved further from ...


Designing Liquid Crystal For Optoacoustic Detection, Michael T. Dela Cruz Mar 2019

Designing Liquid Crystal For Optoacoustic Detection, Michael T. Dela Cruz

Theses and Dissertations

This research impacts the development of a cost-saving, on-chip device that can replace a wide range of costly, bulky sensors for commercial and defense applications. In particular, the goals of this work were to design and test a sensor that uses the optical properties of liquid crystal (LC) to detect acoustic waves. This began with developing a method to fine-tune the optical features of the liquid crystal. Statistical analysis of select experimental variables, or factors, lead to ideal settings of those variables when creating the sensor. A two-factor and three-factor experiment were separately conducted and analyzed as a preliminary demonstration ...


Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes Mar 2019

Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes

Theses and Dissertations

A new single stepped-iris waveguide technique is used to nondestructively determine the permittivity and permeability of conductor-backed media. This thesis will demonstrate a proof-of-concept that obtains two independent reflection measurements with a magnetic radar absorbing material (magRAM). Using a two measurement procedure, in which, the first measurement will apply a single rectangular waveguide to a known conductor-backed absorbing material under test (MUT) and the second measurement will insert a stepped-iris in between the single rectangular waveguide and MUT reducing the aperture to retrieve two independent electromagnetic properties (i.e. permittivity and permeability). The theoretical reflection coefficients are obtained using a ...


A Focal Plane Array And Electronics Model For Cmos And Ccd Sensors In The Afit Sensor And Scene Emulation Tool (Asset), Fernando D. Fernandez Mar 2019

A Focal Plane Array And Electronics Model For Cmos And Ccd Sensors In The Afit Sensor And Scene Emulation Tool (Asset), Fernando D. Fernandez

Theses and Dissertations

Electro-optical and infrared (EO/IR) sensor models are useful tools that can facilitate understanding a system's behavior without expensive and time-consuming testing of an actual system. EO/IR models are especially important to the military industry where truth data is required but is sometimes impractical to obtain through experimentation due to expense or difficulties in procuring hardware. This work describes implementation of a focal plane array (FPA) model of charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) photodetectors as a component in the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET). The FPA model covers ...


Ballistic Evaluation Of Carbon Nanotube Sheet Material In Multifunctional Applications, Casey M. Keilbarth Mar 2019

Ballistic Evaluation Of Carbon Nanotube Sheet Material In Multifunctional Applications, Casey M. Keilbarth

Theses and Dissertations

Significant development of carbon nanotubes has occurred since they were first studied in the 1990's. Attempts to capture the phenomenal molecular properties in practical applications are gaining ground as new methods of producing CNTs have been developed. This thesis sought to determine if the addition of commercially produced CNT sheets to thin carbon fiber panels improved the ballistic properties of the panel. The difference between 0 and 4 CNT sheets was studied. The hypothesis was that inte- grating CNT sheets into the laminate would increase the projectile energy absorbed by the panel and reduce the damage to the panel ...


Optical And Electron Paramagnetic Resonance Characterization Of Point Defects In Semiconductors, Elizabeth M. Scherrer Mar 2019

Optical And Electron Paramagnetic Resonance Characterization Of Point Defects In Semiconductors, Elizabeth M. Scherrer

Theses and Dissertations

Point defects in two semiconductor materials, both with promising optical properties, are investigated. The first material, CdSiP2, is a nonlinear optical material in which absorption bands due to point defects can hinder performance when used in frequency conversion applications in the infrared. The second material, Sn2P2S6, is a photorefractive material where point defects with specific properties are needed to optimize response in dynamic holography applications. Electron paramagnetic resonance (EPR) spectroscopy is used to identify the electronic structure of defects and their charge states. Correlations between EPR spectra and optical absorption allow assignments for the ...


Simultaneous Transmit And Receive (Star) Antennas For Geo-Satellites And Shared-Antenna Platforms, Elie Germain Tianang Jan 2019

Simultaneous Transmit And Receive (Star) Antennas For Geo-Satellites And Shared-Antenna Platforms, Elie Germain Tianang

Electrical Engineering Graduate Theses & Dissertations

This thesis presents the analysis, design, and experimental characterization of antenna systems considered for shipborne, airborne, and space platforms. These antennas are innovated to enable Simultaneous Transmit and Receive (STAR) at same time and polarization, either at the same, or duplex frequencies. In airborne and shipborne platforms, developed antenna architectures may enhance the capabilities of modern electronic warfare systems by enabling concurrent electronic attack and electronic support operations. In space, and more precisely at geostationary orbit, designed antennas aim to decrease the complexity of conventional phased array systems, thereby increasing their capabilities and attractiveness. All antennas researched are first designed ...


Advanced Load Modulated Power Amplifier Architectures, Prathamesh Hirachandra Pednekar Jan 2019

Advanced Load Modulated Power Amplifier Architectures, Prathamesh Hirachandra Pednekar

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

Power amplifier (PA) applications increasingly require wideband linear operation, such as in carrier aggregation, high-data rate communications as well as several other RF systems including radar, RFID, RF sensing, imaging etc. Additionally, the high peak to average power ratio (PAPR) signals of modern communications systems require operation over a wide dynamic range. Both bandwidth and linearity requirements are at odds with efficiency in conventional amplifier design. As a result, PA design with a simultaneous wideband operation, linearity, and energy efficiency has been a longstanding challenge.

This thesis presents several advanced Load Modulated Balanced Amplifier (LMBA) architectures with a common goal ...


Design, Development, And Prelaunch Calibration Of A Low Cost 118.75 Ghz Temperature Sounding Radiometer For Cubesat Missions, Lavanya Periasamy Jan 2019

Design, Development, And Prelaunch Calibration Of A Low Cost 118.75 Ghz Temperature Sounding Radiometer For Cubesat Missions, Lavanya Periasamy

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

The 118.75 GHz eight-channel, double-side-band scanning temperature sounding radiometer “MiniRad” for CubeSat missions is intended to serve as a demonstrator for a constellation of low cost, quick turn-around millimeter wave and higher frequency passive sounders and imagers for weather forecasting at high spatial and temporal resolution. This radiometer payload, built at the Center for Environmental Technology in partnership with the Colorado Space Grant Consortium and the National Snow and Ice Data Center at the University of Colorado at Boulder, can provide a 3D temperature map from the earth's surface to an altitude of 18~km. For precise prelaunch ...


Wideband Dual-Polarized Digital Direction Of Arrival Sensors, Riley Nelson Pack Jan 2019

Wideband Dual-Polarized Digital Direction Of Arrival Sensors, Riley Nelson Pack

Electrical Engineering Graduate Theses & Dissertations

This thesis presents the design of wideband, dual-polarized direction of arrival (DOA) antennas intended for use with digital processing backends. It is shown that using a digital receiver for DOA allows for wider bandwidth and improvement of the size, weight, and complexity of the antenna system at the cost of traditional design metrics. All antennas are designed using full-wave finite element simulations and are validated with measurements.

Four-arm modulated arm width (MAW) spiral antennas are analyzed for use as digital DOA sensors for linearly-polarized signals. Counter to traditional design procedures, tightly-wound MAW spirals with a small modulation ratio perform significantly ...


Wideband Bi-Static And Monostatic Star Antenna Systems, Prathap Valale Prasannakumar Jan 2019

Wideband Bi-Static And Monostatic Star Antenna Systems, Prathap Valale Prasannakumar

Electrical Engineering Graduate Theses & Dissertations

The thesis presents the design, and development of novel wideband Simultaneous Transmit And Receive (STAR) antenna systems. A STAR or in-band full-duplex system has the potential to double the throughput of a communication channel, which is highly important for the next-generation wireless networks. Similarly, these systems could increase the effectiveness of Electronic Warfare (EW) and Support (S) operation, by facilitating spectrum/channel sensing while jamming. A self-interference (SI) phenomenon, where the transmitter disrupts its own receiver is a major challenge in the practical realization of any radio frequency (RF) system. High isolation (>130 dB) is often needed to overcome this ...


Optically Transparent Antennas And Filters For Smart City Communication, Ryan B. Green Jan 2019

Optically Transparent Antennas And Filters For Smart City Communication, Ryan B. Green

Theses and Dissertations

Incremental usage of mobile devices demand a new generation of wireless networks (5G) to provide faster data rates, more reliable coverage, monitor city infrastructure usage, and increase network capacity. The frequencies proposed for the upcoming 5G network would result in shorter broadcast distances and network dead zones, countered by incorporating transparent antennas into glass high rises. Transparent antennas possess, however a major challenge: low gain. This lower gain can be countered by means of employing antennas in an antenna array, boosting the gain and even giving the array the ability to beam form for the upcoming 5G network. The 5G ...