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2030 full-text articles. Page 57 of 57.

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak 2010 University of Central Florida

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak

Electronic Theses and Dissertations

Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA ...


Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur 2010 University of Central Florida

Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur

Electronic Theses and Dissertations

In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits ...


Epitaxial Growth, Characterization And Application Of Novel Wide Bandgap Oxide Semiconductors, Jeremy Mares 2010 University of Central Florida

Epitaxial Growth, Characterization And Application Of Novel Wide Bandgap Oxide Semiconductors, Jeremy Mares

Electronic Theses and Dissertations

In this work, a body of knowledge is presented which pertains to the growth, characterization and exploitation of high quality, novel II-IV oxide epitaxial films and structures grown by plasma-assisted molecular beam epitaxy. The two compounds of primary interest within this research are the ternary films NixMg1-xO and ZnxMg1-xO and the investigation focuses predominantly on the realization, assessment and implementation of these two oxides as optoelectronic materials. The functioning hypothesis for this largely experimental effort has been that these cubic ternary oxides can be exploited - and possibly even juxtaposed - to realize novel wide band gap optoelectronic technologies. The results of ...


Fast Parameter-Space Sweep Of Wideband Electromagnetic Systems Using Bt-Pod, Wei Wang 2010 University of Massachusetts Amherst

Fast Parameter-Space Sweep Of Wideband Electromagnetic Systems Using Bt-Pod, Wei Wang

Masters Theses 1911 - February 2014

Modeling and design of high frequency electronic systems such as antennas and microwave devices require the rigorous numerical solution of Maxwell’s equa- tions. The frequency-domain (time-harmonic) tangential vector finite element method (TVFEM) for Maxwell equations results in a second-order dynamical electromagnetic model that must be repeatedly solved for multiple frequencies, excitation or material parameters each design loop. This leads to extremely long design turnaround that often is not optimal. This work will propose an accurate, error controllable and ef- ficient multi-parametric model order reduction scheme that significantly accelerate these parameters sweep. At the core of this work is the ...


Technological Challenges Of 1-Dimensional Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Dmitry E. Balabanov, Vladimir I. Burkov, V. V. Koledov, Viacheslav A. Kotov, V. G. Shavrov, Anotoly K. Zvezdin 2010 Edith Cowan University

Technological Challenges Of 1-Dimensional Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Dmitry E. Balabanov, Vladimir I. Burkov, V. V. Koledov, Viacheslav A. Kotov, V. G. Shavrov, Anotoly K. Zvezdin

ECU Publications Pre. 2011

Visible-region magnetic photonic crystals (MPC) designed for higher-order bandgap operation have been proposed to overcome the technological restrictions originating from the strong thickness dependency of the individual magnetic layer properties observed in MPC structures.


Near-Field Radiative Transfer: Thermal Radiation, Thermophotovoltaic Power Generation And Optical Characterization, Mathieu Francoeur 2010 University of Kentucky

Near-Field Radiative Transfer: Thermal Radiation, Thermophotovoltaic Power Generation And Optical Characterization, Mathieu Francoeur

University of Kentucky Doctoral Dissertations

This dissertation focuses on near-field radiative transfer, which can be defined as the discipline concerned with energy transfer via electromagnetic waves at sub-wavelength distances. Three specific subjects related to this discipline are investigated, namely nearfield thermal radiation, nanoscale-gap thermophotovoltaic (nano-TPV) power generation and optical characterization. An algorithm for the solution of near-field thermal radiation problems in one-dimensional layered media is developed, and several tests are performed showing the accuracy, consistency and versatility of the procedure. The possibility of tuning near-field radiative heat transfer via thin films supporting surface phononpolaritons (SPhPs) in the infrared is afterwards investigated via the computation of ...


The Effect Of Curvature Rate On The Received Power In Parabolic Reflector, Amean Al_Safi 2009 Western Michigan University

The Effect Of Curvature Rate On The Received Power In Parabolic Reflector, Amean Al_Safi

Amean S Al_Safi

In this paper we study the effect of curvature rate on the generated electric field at the focus point if the frequency and diameter are constants .We assume that the incident electromagnetic waves distributed uniformly on each point of the reflector surface ;hence we can imagine that this reflector has uniform surface charge ,and this body will generate an electric field on all points in front of it (including the focus point) . This field can be obtained by using coulomb’s law .The derived expression for electric field show that X and Y components will vanish and the electric field ...


Application Of Electromagnetic Waves As A Solution To Some Agricultural Problems, B. M. Ida Idayu, Maryam Ashayer Soltani, Amin Enayati, H. Aliakbarian, Hossein Ameri Mahabadi, M. Moghawemi 2009 Department of Electrical Engineering, University of Malaya

Application Of Electromagnetic Waves As A Solution To Some Agricultural Problems, B. M. Ida Idayu, Maryam Ashayer Soltani, Amin Enayati, H. Aliakbarian, Hossein Ameri Mahabadi, M. Moghawemi

Hossein Ameri Mahabadi

A review of some applications of electromagnetic waves in agriculture is presented. There are many applications in the literature which are categorized in two sections of post-harvest indoor and pre-harvest outdoor applications. Taking a look at the applications suggested, there are still works to be done to industrialize the method. However, the proposed method is promising in special cases when the cost and hazards of other methods are high.


Selective Area Rare-Earth Doping Of Planar Glass Samples For Monolithic Integration Of Optically Passive And Active Waveguides, Faisal Rafiq Mahamd Adikan 2009 University Of Malaya

Selective Area Rare-Earth Doping Of Planar Glass Samples For Monolithic Integration Of Optically Passive And Active Waveguides, Faisal Rafiq Mahamd Adikan

Faisal Rafiq Mahamd Adikan

Successful demonstration of selective area doping of planar glass samples for monolithic integration of optically passive and active devices on a single chip is presented. Salt solution of erbium was delivered onto pre-sintered germano-silicate samples via a syringe. The samples were then consolidated to form dense glass layers containing regions doped with rare earth. Erbium tri-chloride solution, 0.1 M. was used during the solution doping phase, with the resulting erbium atomic percentage ranging from more than 0.1-0.4%, increasing linearly with the number of drips applied. (C) 2008 Elsevier GmbH. All rights reserved.


Ultrathin, Ultrasmooth And Low-Loss Silver Films Via Wetting And Annealing, Weiqiang Chen, Kuo-ping Chen, Mark Thoreson, Alexander Kildishev, Vladimir Shalaev 2009 University of Michigan - Ann Arbor

Ultrathin, Ultrasmooth And Low-Loss Silver Films Via Wetting And Annealing, Weiqiang Chen, Kuo-Ping Chen, Mark Thoreson, Alexander Kildishev, Vladimir Shalaev

Weiqiang Chen

We have demonstrated that a thermal annealing treatment can reduce the optical losses in ultrathin, ultrasmooth, silver films deposited on a Ge wetting layer to values as low as the bulk material value and at the same time maintain an ultrasmooth surface. The annealing effect is sensitive to the annealing temperature and time, both of which should be carefully controlled. This annealing treatment is also effective for Ag–SiO2 multilayer composite films.


Toward Superlensing With Metal-Dielectric Composites And Multilayers, Rasmus Nielsen, Mark Thoreson, Weiqiang Chen, Anders Kristensen, Jørn Hvam, Vladimir Shalaev, Alexandra Boltasseva 2009 University of Michigan - Ann Arbor

Toward Superlensing With Metal-Dielectric Composites And Multilayers, Rasmus Nielsen, Mark Thoreson, Weiqiang Chen, Anders Kristensen, Jørn Hvam, Vladimir Shalaev, Alexandra Boltasseva

Weiqiang Chen

We report on the fabrication of two types of adjustable, near-field superlens designs: metal–dielectric composites and metal–dielectric multilayer films. We fabricated a variety of films with different materials, thicknesses and compositions. These samples were characterized physically and optically to determine their film composition, quality, and optical responses. Our results on metal–dielectric composites indicate that although the real part of the effective permittivity generally follows effective medium theory predictions, the imaginary part does not and substantially higher losses are observed. Going forward, it appears that multilayer metal–dielectric designs are more suitable for sub-diffraction imaging applications because they ...


Hybrid Approach For Brain Tumor Segmentation In Magnetic Resonance Images Using Cellular Neural Networks And Optimization Techniques, D. Selvathi, Henry Selvaraj, S. Thamarai Selvi 2009 University of Nevada, Las Vegas

Hybrid Approach For Brain Tumor Segmentation In Magnetic Resonance Images Using Cellular Neural Networks And Optimization Techniques, D. Selvathi, Henry Selvaraj, S. Thamarai Selvi

Henry Selvaraj

Tumor segmentation from brain magnetic resonance image data is an important but time consuming task performed manually by medical experts. Automating this process is challenging due to the high diversity in appearance of tumor tissue among different patients and in many cases, similarity between tumor and normal tissue. This paper deals with an efficient segmentation algorithm for extracting brain tumors in magnetic resonance images using Cellular Neural Networks (CNN). Learning CNN templates values are formulated as an optimization problem. The template coefficients (weights) of an CNN which will give a desired performance, can be derived by learning genetic algorithm and ...


Fabrication And Optical Characterizations Of Smooth Silver-Silica Nanocomposite Films, Weiqiang Chen, Mark Thoreson, Alexander Kildishev, Vladimir Shalaev 2009 University of Michigan - Ann Arbor

Fabrication And Optical Characterizations Of Smooth Silver-Silica Nanocomposite Films, Weiqiang Chen, Mark Thoreson, Alexander Kildishev, Vladimir Shalaev

Weiqiang Chen

We have studied the surface-smoothing effect of an ultrathin germanium (Ge) layer on silver (Ag)-silica (SiO2) nanocomposite films for superlensing applications. Our experimental results indicate that inserting a thin Ge layer below the silver-silica composite films can reduce the final surface root-mean-squared (RMS) roughness to under 1 nm. Additionally, the metal nanostructure plays a role in both the smoothing effect and the optical properties of the nanocomposite films. Our experimental results show that the Bruggeman effective medium theory (EMT) is not sufficiently accurate to describe some properties of our nanocomposite films. In addition to the constituent materials and their ...


On The Interaction Of An Eddy Current Coil With A Right-Angled Conductive Wedge, John R. Bowler, Theodoros Theodoulidis 2009 Iowa State University

On The Interaction Of An Eddy Current Coil With A Right-Angled Conductive Wedge, John R. Bowler, Theodoros Theodoulidis

John R. Bowler

A fundamental problem in eddy-current nondestructive evaluation is one of finding the quasi-static electromagnetic field of a cylindrical coil in the vicinity of the edge of a metal block. Although the field can be calculated numerically, an effective analytical approach can potentially provide a better understanding of the edge fields and form the basis of a procedure for solving a whole class of related edge problems including edge structures that contain corner cracks. One can represent the metal block as a conductive quarter space in an unbounded region. However, it has been found that the analysis is more straightforward if ...


Resistivity Recovery In Gd5si2.09ge1.91 By Annealing, Ravi L. Hadimani, David C. Jiles 2009 Cardiff University

Resistivity Recovery In Gd5si2.09ge1.91 By Annealing, Ravi L. Hadimani, David C. Jiles

Ravi L Hadimani

Irreversible change in resistivity occurs in Gd5(SixGe1−x)4 (with 0.41


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