A Complex-Envelope Fdtd Formulation Using Real-Valued Field-Variables,
2014
University of Mississippi
A Complex-Envelope Fdtd Formulation Using Real-Valued Field-Variables, Qi Liu
Electronic Theses and Dissertations
Use of the complex-envelope (CE) representation of band-pass limited sources and their resulting fields increases the allowable time-step in finite-difference time-domain (FDTD) simulations. The complex envelope representation transforms band-pass limited fields and sources to complex-valued low-pass limited form and Maxwells equations from real-valued partial differential equations (PDEs) to complex-valued PDEs. Previous CE FDTD schemes have used complex valued difference equations in terms of complex valued field quantities to approximate these complex PDEs. This choice requires the use of complex numbers and complex operations in the computer program implementing the solution. An alternative CE FDTD scheme using only real numbers and …
Multifunctional, Multimaterial Particle Fabrication Via An In-Fiber Fluid Instability,
2014
University of Central Florida
Multifunctional, Multimaterial Particle Fabrication Via An In-Fiber Fluid Instability, Joshua Kaufman
Electronic Theses and Dissertations
Spherical micro- and nano-particles have found widespread use in many various applications from paint to cosmetics to medicine. Due to the multiplicity of desired particle material(s), structure, size range, and functionality, many approaches exist for generating such particles. Bottom-up methods such as chemical synthesis have a high yield and work with a wide range of materials; however, these processes typically lead to large polydispersity and cannot produce structured particles. Top-down approaches such as microfluidics overcome the polydispersity issue and may produce a few different structures in particles, but at lower rates and only at the micro-scale. A method that can …
3d Printed Spatially Variant Metamaterials,
2014
University of Texas at El Paso
3d Printed Spatially Variant Metamaterials, Cesar Roman Garcia
Open Access Theses & Dissertations
The recent advancement in 3D printing has created a new way to design electronics and electromagnetic devices. This allows for a new breed of non-planar designs to be used, fully exploiting all three dimensions like never before. More functions can be fit into the same amount of space, products with novel form factors can be more easily manufactured, interconnects can be routed more smoothly, interfaces can be better implemented, electrical and mechanical functions can be comingled, and entirely new device paradigms will be invented. When departing from traditional planar topologies many new problems arise like signal integrity, crosstalk, noise, and …
Digitally Manufactured Spatially Variant Photonic Crystals,
2014
University of Texas at El Paso
Digitally Manufactured Spatially Variant Photonic Crystals, Javier Jair Pazos
Open Access Theses & Dissertations
Metamaterials and photonic crystals are engineered composites that exhibit electromagnetic properties superior to those found in nature. They have been shown to produce novel and useful phenomena that allow extraordinary control over the electromagnetic field. One of these phenomena is self-collimation, an effect observed in photonic crystals in which a beam of light propagates without diffraction and is forced to flow in the direction of the crystal. Self-collimation however, like many of the mechanisms enabled through dispersion engineering, is effective in directions only along the principal axes of the lattice. To this effect, a general purpose synThesis procedure was developed …
Photonic Filtering For Applications In Microwave Generation And Metrology,
2014
University of Central Florida
Photonic Filtering For Applications In Microwave Generation And Metrology, Marcus Bagnell
Electronic Theses and Dissertations
This work uses the photonic filtering properties of Fabry-Perot etalons to show improvements in the electrical signals created upon photodetection of the optical signal. First, a method of delay measurement is described which uses multi-heterodyne detection to find correlations in white light signals at 20 km of delay to sub millimeter resolution. By filtering incoming white light with a Fabry-Perot etalon, the pseudo periodic signal is suitable for measurement by combining and photodetecting it with an optical frequency comb. In this way, optical data from a large bandwidth can be downconverted and sampled on low frequency electronics. Second, a high …
Parity-Time And Supersymmetry In Optics,
2014
University of Central Florida
Parity-Time And Supersymmetry In Optics, Mohammad Ali Miri
Electronic Theses and Dissertations
Symmetry plays a crucial role in exploring the laws of nature. By exploiting some of the underlying analogies between the mathematical formalism of quantum mechanics and that of electrodynamics, in this dissertation we show that optics can provide a fertile ground for studying, observing, and utilizing some of the peculiar symmetries that are currently out of reach in other areas of physics. In particular, in this work, we investigate two important classes of symmetries, parity-time symmetry (PT) and supersymmetry (SUSY), within the context of classical optics. The presence of PT symmetry can lead to entirely real spectra in non-Hermitian systems. …
Reference Compensation For Localized Surface-Plasmon Resonance Sensors,
2014
University of Kentucky
Reference Compensation For Localized Surface-Plasmon Resonance Sensors, Neha Nehru
Theses and Dissertations--Electrical and Computer Engineering
Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated for label free detection of various biological and chemical interactions. When compared to other optical sensing techniques, LSPR sensors offer label-free detection of biomolecular interactions in localized sensing volume solutions. However, these sensors also suffer from a major disadvantage – LSPR sensors remain highly susceptible to interference because they respond to both solution refractive index change and non-specific binding as well as specific binding of the target analyte. These interactions can severely compromise the measurement of the target analyte in a complex unknown media and hence limit …
Error Control And Efficient Memory Management For Sparse Integral Equation Solvers Based On Local-Global Solution Modes,
2014
University of Kentucky
Error Control And Efficient Memory Management For Sparse Integral Equation Solvers Based On Local-Global Solution Modes, Jun-Shik Choi
Theses and Dissertations--Electrical and Computer Engineering
This dissertation presents and analyzes two new algorithms for sparse direct solution methods based on the use of local-global solution (LOGOS) modes. One of the new algorithms is a rigorous error control strategy for LOGOS-based matrix factorizations that utilize overlapped, localizing modes (OL-LOGOS) on a shifted grid. The use of OL-LOGOS modes is critical to obtaining asymptotically efficient factorizations from LOGOS-based methods. Unfortunately, the approach also introduces a non-orthogonal basis function structure. This can cause errors to accumulate across levels of a multilevel implementation, which has previously posed a barrier to rigorous error control for the OL-LOGOS factorization method. This …
A Multi-Physics Computational Approach To Simulating Thz Photoconductive Antennas With Comparison To Measured Data And Fabrication Of Samples,
2014
University of Kentucky
A Multi-Physics Computational Approach To Simulating Thz Photoconductive Antennas With Comparison To Measured Data And Fabrication Of Samples, Darren Ray Boyd
Theses and Dissertations--Electrical and Computer Engineering
The frequency demands of radiating systems are moving into the terahertz band with potential applications that include sensing, imaging, and extremely broadband communication. One commonly used method for generating and detecting terahertz waves is to excite a voltage-biased photoconductive antenna with an extremely short laser pulse. The pulsed laser generates charge carriers in a photoconductive substrate which are swept onto the metallic antenna traces to produce an electric current that radiates or detects a terahertz band signal. Therefore, analysis of a photoconductive antenna requires simultaneous solutions of both semiconductor physics equations (including drift-diffusion and continuity relations) and Maxwell’s equations. A …
Visible-Light Photocatalyzed Cross-Linking Of Diacetylene Ligands By Quantum Dots To Improve Their Aqueous Colloidal Stability,
2014
University of Arkansas, Fayetteville
Visible-Light Photocatalyzed Cross-Linking Of Diacetylene Ligands By Quantum Dots To Improve Their Aqueous Colloidal Stability, Marion G. Götz, Hiroko Takeuchi, Matthew J. Goldfogel, Julia M. Warren, Brandon D. Fennel, Colin D. Heyes
Chemistry & Biochemistry Faculty Publications and Presentations
Ligand cross-linking is known to improve the colloidal stability of nanoparticles, particularly in aqueous solutions. However, most cross-linking is performed chemically, in which it is difficult to limit interparticle cross-linking, unless performed at low concentrations. Photochemical cross-linking is a promising approach but usually requires ultraviolet (UV) light to initiate. Using such high-energy photons can be harmful to systems in which the ligand–nanoparticle bond is fairly weak, as is the case for the commonly used semiconductor quantum dots (QDs). Here, we introduce a novel approach to cross-link thiolated ligands on QDs by utilizing the photocatalytic activity of QDs upon absorbing visible …
High Resolution Time-Resolved Imaging System In The Vacuum Ultraviolet Region,
2014
University of Central Florida
High Resolution Time-Resolved Imaging System In The Vacuum Ultraviolet Region, Yuseong Jang
Electronic Theses and Dissertations
High-power debris-free vacuum ultraviolet (VUV) light sources have applications in several scientific and engineering areas, such as high volume manufacturing lithography and inspection tools in the semiconductor industry, as well as other applications in material processing and photochemistry. For the past decades, the semiconductor industry has been driven by what is called "Moore's Law". The entire semiconductor industry relies on this rule, which requires chip makers to pack transistors more tightly with every new generation of chips, shrinking the size of transistors. The ability to solve roadmap challenges is, at least partly, proportional to our ability to measure them. The …
Semiconductor Laser Based On Thermoelectrophotonics,
2014
University of Central Florida
Semiconductor Laser Based On Thermoelectrophotonics, Xiaohang Liu
Electronic Theses and Dissertations
This dissertation presents to our knowledge the first demonstration of a quantum well (QW) laser monolithically integrated with internal optical pump based on a light emitting diode (LED). The LED with high efficiency is operated in a thermoelectrophotonic (TEP) regime for which it can absorb both its own emitted light and heat. The LED optical pump can reduce internal optical loss in the QW laser, and enables monolithically integrated TEP heat pumps to the semiconductor laser. The design, growth and fabrication processes of the laser chip are discussed, and its experimental data is presented. In order to further increase the …
Multimaterial Fibers In Photonics And Nanotechnology,
2014
University of Central Florida
Multimaterial Fibers In Photonics And Nanotechnology, Guangming Tao
Electronic Theses and Dissertations
Recent progress in combing multiple materials with distinct optical, electronic, and thermomechanical properties monolithically in a kilometer-long fiber drawn from a preform offers unique multifunctionality at a low cost. A wide range of unique in-fiber devices have been developed in fiber form-factor using this strategy. Here, I summary my recent results in this nascent field of 'multimaterial fibers'. I will focus on my achievements in producing robust infrared optical fibers and in appropriating optical fiber production technology for applications in nanofabrication. The development of optical components suitable for the infrared (IR) is crucial for applications in this spectral range to …
Laser Filamentation - Beyond Self-Focusing And Plasma Defocusing,
2014
University of Central Florida
Laser Filamentation - Beyond Self-Focusing And Plasma Defocusing, Khan Lim
Electronic Theses and Dissertations
Laser filamentation is a highly complex and dynamic nonlinear process that is sensitive to many physical parameters. The basic properties that define a filament consist of (i) a narrow, high intensity core that persists for distances much greater than the Rayleigh distance, (ii) a low density plasma channel existing within the filament core, and (iii) a supercontinuum generated over the course of filamentation. However, there remain many questions pertaining to how these basic properties are affected by changes in the conditions in which the filaments are formed; that is the premise of the work presented in this dissertation. To examine …
Distribution Of Laser Induced Heating In Multi-Component Chalcogenide Glass And Its Associated Effects,
2014
University of Central Florida
Distribution Of Laser Induced Heating In Multi-Component Chalcogenide Glass And Its Associated Effects, Laura Sisken
Electronic Theses and Dissertations
Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much …
Highly-Sensitive Stoichiometric Analysis Of Yag Ceramics Using Laser-Induced Breakdown Spectroscopy (Libs),
2014
University of Central Florida
Highly-Sensitive Stoichiometric Analysis Of Yag Ceramics Using Laser-Induced Breakdown Spectroscopy (Libs), Jahromi, Ali Kazemi
Electronic Theses and Dissertations
Transparent ceramics are an important class of optical materials with applications in high-strength windows, radiation detectors and high-power lasers. Despite the many successful developments of the past decades, their challenging fabrication still needs to be perfected to achieve a better consistency in optical quality. In particular, ternary phase materials such as Yttrium Aluminum Garnet (YAG, Y3Al5O12), a long standing high-power laser host, require a precise control of stoichiometry, often beyond the precision of current analytical techniques, in order to reduce scattering losses and the presence of deleterious point defects. This work explores the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for …
Broad Bandwidth, All-Fiber, Thulium-Doped Photonic Crystal Fiber Amplifier For Potential Use In Scaling Ultrashort Pulse Peak Powers,
2014
University of Central Florida
Broad Bandwidth, All-Fiber, Thulium-Doped Photonic Crystal Fiber Amplifier For Potential Use In Scaling Ultrashort Pulse Peak Powers, Alex Sincore
Electronic Theses and Dissertations
Fiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be simultaneously attained using photonic crystal fibers. Thulium-doped fiber lasers are attractive for high peak power ultrashort pulse systems. They offer a broad gain bandwidth, capable of amplifying sub-100 femtosecond pulses. The longer …
Techniques For Characterization Of Third Order Optical Nonlinearities,
2014
University of Central Florida
Techniques For Characterization Of Third Order Optical Nonlinearities, Manuel Ferdinandus
Electronic Theses and Dissertations
This dissertation describes the development of novel techniques for characterization of nonlinear properties of materials. The dissertation is divided into two parts, a background and theory section and a technique development section. In the background and theory section we explain the origins of the nonlinear optical response of materials across many different spatial and temporal scales. The mechanisms that we are most interested in are the electronic nuclear and reorientational responses, which occur on the range of sub-femtosecond to several picoseconds. The electronic mechanism is due to the electrons of a material experiencing a non-parabolic potential well due a strong …
Multimaterial Fibers And Tapers A Platform For Nonlinear Photonics And Nanotechnology,
2014
University of Central Florida
Multimaterial Fibers And Tapers A Platform For Nonlinear Photonics And Nanotechnology, Soroush Shabahang
Electronic Theses and Dissertations
The development of optical sources and components suitable for the mid-infrared is crucial for applications in this spectral range to reach the maturity level of their counterparts in the visible and near-infrared spectral regimes. The recent commercialization of quantum cascade lasers is leading to further interest in this spectral range. Wideband mid-infrared coherent sources, such as supercontinuum generation, have yet to be fully developed. A mid-infrared supercontinuum source would allow for unique applications in spectroscopy and sensing. Over the last decade, it has been shown that high-index confinement in highly nonlinear fibers pumped with high-peak-power pulses is an excellent approach …
Investigating Strain Transfer In Polymer Coated Structures For The Health Monitoring Of Aerospace Vehicles Using Polymer Photonic Waveguides,
2014
RMIT University
Investigating Strain Transfer In Polymer Coated Structures For The Health Monitoring Of Aerospace Vehicles Using Polymer Photonic Waveguides, Graham Wild, Bronwyn Fox, Kevin Magniez, Steven Hinckley, Scott Wade, G Carman
Research outputs 2014 to 2021
In this work, we present the concept of planar polymer photonic waveguides for the health monitoring of aerospace structures. Here a polymer layer is deposited onto the material/structure to be monitored. Within the polymer layer, waveguides are created after deposition. These waveguides can then be used as 'optical fibres' for optical fibre sensing methodologies. In investigating the use of polymer photonic waveguides the question to be answered is: does the strain in the test material transfer to the polymer layer, such that the value to be measured optically is reliable and indicative of the true strain in the test structure? …
