Engineering Commons^™

Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis proposes a light-weight, compact, and accurate optical micro-seismometer that could be used in many applications, such as planetary exploration. The sensor proposed here is based on the principle of whispering gallery optical mode (WGM) resonance shifts of a dielectric micro-resonator due to disturbances of its evanescent field. The micro-seismometer could be used in place of the traditional bulky seismometers. The design of a waveguide-resonator and mechanical structure to disturb the evanescent field are presented. A proof-of-concept a seismometer model that uses a 5µm ring resonator is numerically tested with actual seismic data. The results show that a WGM-based …

Optimizing The Plasmonic Enhancement Of Light In Metallic Nanogap Structures For Surface-Enhanced Raman Spectroscopy, Stephen Joseph Bauman

Graduate Theses and Dissertations

Technology based on the interaction between light and matter has entered something of a renaissance over the past few decades due to improved control over the creation of nanoscale patterns. Tunable nanofabrication has benefitted optical sensing, by which light is used to detect the presence or quantity of various substances. Through methods such as Raman spectroscopy, the optical spectra of solid, liquid, or gaseous samples act as fingerprints which help identify a single type of molecule amongst a background of potentially many other chemicals. This technique therefore offers great benefit to applications such as biomedical sensors, airport security, industrial waste …

Growth And Characterization Of Silicon-Germanium-Tin Semiconductors For Future Nanophotonics Devices, Bader Saad Alharthi

Graduate Theses and Dissertations

The bright future of silicon (Si) photonics has attracted research interest worldwide. The ultimate goal of this growing field is to develop a group IV based Si foundries that integrate Si-photonics with the current complementary metal–oxide–semiconductor (CMOS) on a single chip for mid-infrared optoelectronics and high speed devices. Even though group IV was used in light detection, such as photoconductors, it is still cannot compete with III-V semiconductors for light generation. This is because most of the group IV elements, such as Si and germanium (Ge), are indirect bandgap materials. Nevertheless, Ge and Si attracted industry attention because they are …

Growth And Behaviors Of Inn/Gan Multiple Quantum Wells By Plasma-Assisted Molecular Beam Epitaxy, Chen Li

Graduate Theses and Dissertations

Fully realizing the potential of InGaN semiconductors requires high quality materials with arbitrary In-content. To this date the growth of In-rich InGaN films is still challenging since it suffers from the low growth temperatures and many detrimental alloying problems. InN/GaN multiple quantum wells (MQWs) and super lattices (SLs) are expected to be promising alternatives to random InGaN alloys since in principle they can achieve the equivalent band gap of InGaN random alloys with arbitrarily high In-content and at the same time bypass many growth difficulties.

This dissertation focuses on studying the growth mechanisms, structural properties and energy structures of InN/GaN …

Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh

Doctoral Dissertations

Metamaterials (MMs) are nanocomposite materials consisting of metal-dielectric resonators much smaller in size than the wavelength of the incident light. Common examples of metamaterials are based on split ring resonators (SRRs), parallel wires or strips and fishnet structures. These types of materials are designed and fabricated in order to provide unique optical responses to the incident electromagnetic radiation that are not available in naturally existing materials. The MMs can exhibit unusual properties such as strong magnetism at terahertz (THz) and optical frequencies. Additionally, negative index materials (NIMs) can provide negative index of refraction which can be used in many applications …

Electromagnetic Wave-Matter Interactions In Complex Opto-Electronic Materials And Devices, Raj Kumar Vinnakota

Doctoral Dissertations

This dissertation explores the fundamentals of light-matter interaction towards applications in the field of Opto-electronic and plasmonic devices. In its core, this dissertation attempts and succeeds in the the modeling of light-matter interactions, which is of high importance for better understanding the rich physics underlying the dynamics of electromagnetic field interactions with charged particles. Here, we have developed a self-consistent multi-physics model of electromagnetism, semiconductor physics and thermal effects which can be readily applied to the field of plasmotronics and Selective Laser Melting (SLM). Plasmotronics; a sub-field of photonics has experienced a renaissance in recent years by providing a large …

Hyperspectral Imaging For Characterizing Single Plasmonic Nanostructure And Single-Cell Analysis, Nishir Sanatkumar Mehta

LSU Master's Theses

Orientation of plasmonic nanostructures is an important feature in many nanoscale applications such as photovoltaics, catalyst, biosensors DNA interactions, protein detections, hotspot of surface-enhanced Raman spectroscopy (SERS), and fluorescence resonant energy transfer (FRET) experiments. Silver nanocubes with significant spectral signatures between 400-700 nm are observed in this experimental research. Whereas study of single cells will enable the analysis of cell-to-cell variations within a heterogeneous population. These variations are important for further analysis and understanding of disease propagation, drug development, stem cell differentiation, embryos development, and how cells respond to each other and their environment. Adipose-derived mesenchymal stem cells possess the …

Thermal And Mechanical Energy Harvesting Using Lead Sulfide Colloidal Quantum Dots, Taher Ghomian

LSU Doctoral Dissertations

The human body is an abundant source of energy in the form of heat and mechanical movement. The ability to harvest this energy can be useful for supplying low-consumption wearable and implantable devices. Thermoelectric materials are usually used to harvest human body heat for wearable devices; however, thermoelectric generators require temperature gradient across the device to perform appropriately. Since they need to attach to the heat source to absorb the heat, temperature equalization decreases their efficiencies. Moreover, the electrostatic energy harvester, working based on the variable capacitor structure, is the most compatible candidate for harvesting low-frequency-movement of the human body. …

A Narrow-Wall Complementary-Split-Ring Slotted Waveguide Antenna For High-Power-Microwave Applications, Xuyuan Pan

Electrical and Computer Engineering ETDs

A narrow-band, rugged, complementary-split-ring (CSR) slotted waveguide antenna (SWA) with significant size reduction is presented. The antenna is to be vertically front mounted on a land vehicle, with a horizontally polarized fan-beam radiation pattern. The radiation characteristics of a CSR slot in the narrow-wall of a rectangular waveguide are studied for the first time in this work. Both simulation and experimental results show that the complementary-split-ring slot radiates a linearly polarized wave with a total efficiency and gain close to those of conventional longitudinal slots, while the proposed CSR slots have a maximal outer diameter of 0.23λ₀, much …

Standing-Wave Dielectric Array Antennas, Ayman Althuwayb

Electrical Engineering Theses and Dissertations

Due to the evolutions in wireless communication systems, antenna engineers have been confronting a number of challenges regarding improving the performance of antennas, miniaturizing the size as well as considering the fabrication simplicity. Although dielectric resonator antennas typically suffer from exhibiting low gain, they have been thoroughly under investigating as they are being excellent candidates to be utilized to fulfill contemporary communication systems requirements and specifications, especially at high-frequency ranges. The reason behind this solicitude is because they have several advantageous features, including but not limited to the simplicity of the used excitation mechanism and fabrication easiness.

One of the …

Investigation Of Opto-Mechanics In Thin-Film Photonic Crystal Membranes, Brett D. Poulsen

Electronic Thesis and Dissertation Repository

Opto-mechanical interactions in photonic crystals (PC) require further investigation for their realization in practical applications. In particular their dynamic response and opto-mechanical coupling is not well understood. The static response of a thin-film 2D PC membrane was studied and the mechanical sensitivity of a static pressure sensor was increased by a factor of 4.9 times. A novel model formulation, correctly accounting for the fluid-structure interaction and the influence of nano-features, was developed to describe the dynamic response of a thin-film 2D PC membrane. The model accurately predicted damping response to within 10% as compared to experimental measurements. A novel 2D …

Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott

Arts & Sciences Electronic Theses and Dissertations

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development …

Indirect Imaging Using Heterodyne Remote Digital Holography, Muralidhar Madabhushi Balaji

Electrical Engineering Theses and Dissertations

Conventional line-of-sight imaging techniques rely on detecting light paths bouncing from the object and reaching directly to the detector. Absence of any such direct light paths from object to detector results in a failure to recover any useful information using conventional techniques. The absence of direct light paths from object to detector can be observed in several real-world scenarios such as looking around a corner, imaging through turbid media, imaging through tissue etc.

The focus of this thesis is pertaining to the problem of looking around corners (or) imaging object hidden from line of sight at macroscopic scales. This thesis …

Room Temperature Operation Of Quantum Cascade Lasers Monolithically Integrated Onto A Lattice-Mismatched Substrate, Rowel Go

Electronic Theses and Dissertations

Quantum Cascade Lasers (QCLs) are semiconductor devices that, currently, have been observed to emit radiation from ~ 2.6 μm to 250 μm (1 to 100 terahertz range of frequencies.) They have established themselves as the laser of choice for spectroscopic gas sensing in the mid-wavelength infrared (3-8 μm) and long-wavelength infrared (8-15 μm) region. In the 4-12 μm wavelength region, the highest performing QCL devices, in terms of wall-plug efficiency and continuous wave operation, are indium phosphide (InP) based. The ultimate goal is to incorporate this InP-based QCL technology to silicon (Si) substrate since most opto-electronics are Si-based. The main …

Opto-Thermal Characterization Of Plasmon And Coupled Lattice Resonances In 2-D Metamaterial Arrays, Vinith Bejugam

Graduate Theses and Dissertations

Growing population and climate change inevitably requires longstanding dependency on sustainable sources of energy that are conducive to ecological balance, economies of scale and reduction of waste heat. Plasmonic-photonic systems are at the forefront of offering a promising path towards efficient light harvesting for enhanced optoelectronics, sensing, and chemical separations. Two-dimensional (2-D) metamaterial arrays of plasmonic nanoparticles arranged in polymer lattices developed herein support thermoplasmonic heating at off-resonances (near infrared, NIR) in addition to regular plasmonic resonances (visible), which extends their applicability compared to random dispersions. Especially, thermal responses of 2-D arrays at coupled lattice resonance (CLR) wavelengths were comparable …

High-Sn-Content Gesn Alloy Towards Room-Temperature Mid Infrared Laser, Wei Dou

Graduate Theses and Dissertations

Si photonics is a rapidly expanding technology that integrates photonic circuits onto a Si substrate. The integration of Si electronics and photonics has been a successful technology for a wide range of applications. Group-IV alloy GeSn has drawn great attentions as a complementary metal–oxide–semiconductor compatible optoelectronic material for Si photonics. The devices based on GeSn alloy could be monolithically integrated into well-established and high-yield Si integrated circuits, which is favorable for chip-scale Si photonics featuring smaller size, lower cost, and higher reliability.

The relaxed GeSn with high material quality and high Sn composition is highly desirable to cover mid-infrared wavelength. …

Hybrid Perovskite Characterization And Device Applications., Kasun Fernando

Electronic Theses and Dissertations

Hybrid perovskites are a group of materials that has shown a great impact in the field of scientific research in the past decade due to the efficiency gain within a short period of time. Hot casting is one technique that has been producing high efficient and stable solar cells. Electrical transportation of lateral device structure by such film is explored to understand basic properties and predict possible device applications using it. Under dark, memristive ability of the film was explored using various experiments. Unique uni-polar memristor ability was observed. Using the experimental results, a model is hypothesized using the concepts …

High Dynamic Range Optical Devices And Applications., Elijah Robert Jensen

Electronic Theses and Dissertations

Much of what we know about fundamental physical law and the universe derives from observations and measurements using optical methods. The passive use of the electromagnetic spectrum can be the best way of studying physical phenomenon in general with minimal disturbance of the system in the process. While for many applications ambient visible light is sufficient, light outside of the visible range may convey more information. The signals of interest are also often a small fraction of the background, and their changes occur on time scales so quickly that they are visually imperceptible. This thesis reports techniques and technologies developed …

Pulse Sharpening Circuit For Explosive Emission Cathode Driver, Nicholas D. Kallas

Electrical and Computer Engineering ETDs

Explosive field emission cathodes (EEC), used for the generation of relativistic electron beams, require short rise-time high-voltage pulses in order to minimize the extraction of off-energy electrons. To this end, a rise-time sharpening circuit has been developed at the Los Alamos National Laboratory (LANL). The circuit consists of a 7 nF water-filled peaking capacitor with an integrated self-breakdown switch designed to operate up to -300 kV. This unit is intended to reduce the rise-time of a 4-stage Type-E PFN Marx Generator that will be used to study operational characteristics of velvet cathodes. Simulations of the peaking circuit show a reduction …

Microwave Characterization Of Printable Dielectric Inks Using Additive Manufacturing Methods, Seth York

USF Tampa Graduate Theses and Dissertations

Two methods of dielectric characterization are presented that offer quick and cost-effective solutions for screening complex dielectric material properties. Through Direct-Print Additive Manufacturing (DPAM) methods, a dielectric material of choice is dispensed into a capacitor structure and characterized through 1-port s-parameter measurements. The presented methods use fixtures that are modeled and validated through simulation then implemented in practice. Advanced simulations are performed to gain insights which are used to optimize the dielectric characterization performance of the fixtures. Additional investigations are performed which investigate the durability of the fixture and material within by exposing the combination to rough environmental conditions for …

Novel Compact Narrow-Linewidth Mid-Infrared Lasers For Sensing Applications, Behsan Behzadi

Optical Science and Engineering ETDs

The mid-infrared (2-14 μm) spectral region contains the strong absorption lines of many important molecular species, which make this region crucial for several well-know applications such as spectroscopy, chemical and biochemical sensing, security, and industrial monitoring. To fully exploit this region through absorption spectroscopic techniques, compact and low-cost narrow-linewidth (NLW) mid-infrared (MIR) laser sources are of primary importance.

This thesis is focused on three novel compact NLW MIR lasers: demonstration and characterization of a new glass-based spherical microlaser, investigation of the performance of a novel fiber laser, and the design of a monolithic laser on a silicon chip. Starting with …

Additively Manufactured On-Package Multipolar Antenna Systems For Harsh Communication Channels, Ramiro A. Ramirez-Hernandez

USF Tampa Graduate Theses and Dissertations

Four main aspects are studied and explored throughout this dissertation: (1) On-Package Multipolar antenna system design for integration with commercial wireless sensor nodes for machine-to-machine communication applications; (2) Development of a novel MMIC packaging process and subsequent antenna integration for chip-to-chip communication applications, (3) Design and characterization of additively manufactured lumped passive elements for integration with MMIC and hybrid circuits, (4) Design and characterization of antennas for on- and off-metal radio frequency identification (RFID) applications.

This work presents the design of different 3-D printed tripolar antenna systems operating at 2.4 GHz. The antennas are designed for integration with commercial wireless …

Wind Turbine Design: Analysis And Experimentation Of Electro-Magnetic Alternator Design, Mark Hans Ewald Steinke

Honors Projects

This article explores the alternator designs for small scale wind turbines and the aspects that affect the performance of these alternators. It explores the design and testing process used to quantify, visualize, and understand the relationship between the wind turbine stator design and the performance. Additionally, the paper analyzes the data collection method using a test jig powered by a hydraulic motor set up by previous groups of students and the data intended to be collected using actual field tests on Whidbey Island located at Camp Casey. These tests were intended to identify favorable combinations of alternators and blades. However, …

Brushless Direct Current Motor Control For Inspired Flight, Aidan James Mccoy

Computer Science and Software Engineering

Brushless direct current motors have become a very common part of many modern electronics. Although they are more expensive and less robust than conventional brushed direct current motors, they provide large advantages in control, power output, longevity as well as efficiency. To make these motors run, they need more than just power. Each motor needs a separate motor controller that is responsible for taking in a signal for what speed/torque to run the motor at, and then managing the current flow to the motor to keep it spinning while fitting within these boundaries. Brushless direct current motors have a set …

The Design, Building, And Testing Of A Constant On Discreet Jammer For The Ieee 802.15.4/Zigbee Wireless Communication Protocol, Alexandre J. Marette

Master's Theses

As wireless protocols become easier to implement, more products come with wireless connectivity. This latest push for wireless connectivity has left a gap in the development of the security and the reliability of some protocols. These wireless protocols can be used in the growing field of IoT where wireless sensors are used to share information throughout a network. IoT is being implemented in homes, agriculture, manufactory, and in the medical field. Disrupting a wireless device from proper communication could potentially result in production loss, security issues, and bodily harm. The 802.15.4/ZigBee protocol is used in low power, low data rate, …

Adaptation Of Vt-Dbr Lasers For Lidar, Luke Horowitz

Master's Theses

Vernier Tuned Distributed Bragg Reflector (VT-DBR) lasers have had great success in the field of Swept-Source Optical Coherence Tomography (SS-OCT) due to their continuous and nearly 40 nm wavelength tuning range in a single longitudinal mode. Fast sweeps allow for real time imaging with micrometer resolution at a distance of a few centimeters. While this laser has proven quite useful as a medical imaging tool via OCT, it has yet to similarly prove itself for general light detection and ranging (LIDAR) applications due to range limitations that arise from a finite laser coherence length. The goal of this thesis is …

A Comparative Analysis Of Integrated Optical Waveguide Isolators With Magneto-Optic Layers, Reyhane Oztekin

Electrical Engineering Theses and Dissertations

The objective of this study is to theoretically devise an on-chip optical isolator which is monolithically integrated with a semiconductor waveguide layer yielding low loss. The optical properties of iron are modeled for the use of optical waveguide isolators by improving the Brendel-Bormann model. Our model for iron shows excellent fit with the optical data up to 30 electronvolts (eV). The semiconductor optical waveguide isolator with magneto-optic layers based on non-reciprocal loss shift is developed in this study. Fe, Co, and Ni metals as well as cerium-substituted yttrium iron garnet (Ce:YIG) have been used as magneto-optic layers. We have shown …

Split-Ring Resonator Waveguide Structure Characterization By Simulations, Measurements And Linear Time-Invariant Modeling, Mohamed Aziz Hmaidi

Electrical and Computer Engineering ETDs

Interest in Metamaterials has been rising drastically in the recent years as they have been used in several optical and RF applications, from antennas to perfect lenses and pulsed power devices. Nevertheless, the time-behavior of metamaterials remains opaque and poorly understood.

In this research work, characterization of a metamaterial structure in time and frequency-domain was made through simulations and experiments. The structure consists in a series of edge-side coupled Split Ring Resonators (SRRs) in a below cutoff waveguide. A linear time invariant model of distributed elements has been elaborated as well in an attempt to approach the structure’s behavior. The …

Design Of An All-Dielectric Sublayer For Enhanced Transmittance In Stacked Antenna Array Applications, Matthew Bester

Electronic Thesis and Dissertation Repository

In spatially constrained applications, the overlapping of antenna arrays can be unavoidable and its presence can lead to a blockage in the line-of-sight for the underlying antennas. Although previous investigations focused predominantly on the contribution of the ground plane and feed network-which were resolved through the use of frequency selective surfaces and proper feed network design, respectively-it is believed that the ground plane, substrate, and patch regions can emplace a substantial combined impedance. To rectify the transmission through these layers, an all-dielectric implementation is suggested based on the properties of complementary media and Fabry-Perot resonance shifting phenomena. Consequently, both spherical …

Software Defined Radar For Vital Sign Detection, Chandler J. Bauder, James Bates, Steven Engel, James S. Tucker, Fangzhou Liu

Chancellor’s Honors Program Projects

No abstract provided.