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Articles 1 - 30 of 32
Full-Text Articles in Electromagnetics and Photonics
Agricultural Applications For Electromagnetic Exposure, H. Aliakbarian, A. Enayati, Hossein Ameri Mahabadi, M. Ashayer Soltani
Agricultural Applications For Electromagnetic Exposure, H. Aliakbarian, A. Enayati, Hossein Ameri Mahabadi, M. Ashayer Soltani
Hossein Ameri Mahabadi
Despite the advances in bug controlling and antifreezing operations of agricultural products, the devastation of Sunne pests and freezing is still enormous. Traditional treatments such as chemical insecticides for bug controlling and covering to avoid freezing have not been sufficient. In the presented paper, new ideas of using electromagnetic treatment for anti-freezing operation, pre-harvest Sunne pest control, and Orchid flower control are introduced.
Examination Of Energy And Group Velocities In Positive And Negative Index Chiral Materials With And Without Dispersion, Monish Ranjan Chatterjee, Partha P. Banerjee
Examination Of Energy And Group Velocities In Positive And Negative Index Chiral Materials With And Without Dispersion, Monish Ranjan Chatterjee, Partha P. Banerjee
Electrical and Computer Engineering Faculty Publications
Concepts of energy and group velocities, Poynting and propagation vectors are examined for both positive and negative index materials. Known definitions for these entities are explored in terms of the interplay of chirality and dispersion.
Bipolar Cascade Vertical Cavity Surface Emitting Lasers For Rf Photonic Link Applications, William J. Siskaninetz
Bipolar Cascade Vertical Cavity Surface Emitting Lasers For Rf Photonic Link Applications, William J. Siskaninetz
Theses and Dissertations
The development and demonstration of bipolar cascade vertical cavity surface emitting lasers is presented. The systematic approach to designing, fabricating, and characterizing the critical tunnel junction, incorporating the tunnel junction into an edge emitting bipolar cascade laser, and finally the transition to a VCSEL structure is detailed. A novel approach prior to growing and characterizing BC VCSELs was to investigate bipolar cascade light emitting diodes which incorporate the microcavity designs and disentangles the VCSEL cavity effects from the microcavity. The best performing p-doped oxide aperture microcavity design was then used as the microcavity for 1-, 2-, and 3-stage BC …
Nonlinear Dynamical Analysis Of Brain Electrical Activity Due To Exposure To Weak Environmentally Relevant Electromagnetic Fields, Erik Alfonso Nilsen
Nonlinear Dynamical Analysis Of Brain Electrical Activity Due To Exposure To Weak Environmentally Relevant Electromagnetic Fields, Erik Alfonso Nilsen
Doctoral Dissertations
The reports dealing with the effects of weak electromagnetic fields (EMFs) on brain electrical activity have been inconsistent. We suspected that the use of linear models and their associated methods accounted for some of the variability, and we explored the issue by using a novel approach to study the effects of EMFs on the electroencephalogram (EEG) from rabbits and humans. The EEG was embedded in phase space and local recurrence plots were calculated and quantified to permit comparisons between exposed and control epochs from individual subjects. Statistically significant alterations in brain activity were observed in each subject when exposed to …
Analysis Of Beam Propagation In 90-Degree Holographic Recording And Readout Using Transfer Functions And Numerical 2-D-Laplace Inversion, Monish Ranjan Chatterjee, Partha P. Banerjee, George Nehmetallah
Analysis Of Beam Propagation In 90-Degree Holographic Recording And Readout Using Transfer Functions And Numerical 2-D-Laplace Inversion, Monish Ranjan Chatterjee, Partha P. Banerjee, George Nehmetallah
Electrical and Computer Engineering Faculty Publications
Recently, 2-D-Laplace analysis of recording and readout of edge-holograms was reported. Numerical Laplace inversion was examined for simple test cases. Inversion algorithms are applied to examine beam shaping and distortion in photovoltaic and photorefractive materials.
Sub-Surface Navigation Using Very-Low Frequency Electromagnetic Waves, Alan L. Harner
Sub-Surface Navigation Using Very-Low Frequency Electromagnetic Waves, Alan L. Harner
Theses and Dissertations
This research proposes two schemes utilizing very-low frequency (VLF) electromagnetic waves to navigate underground. The first scheme consists of using above-ground beacon transmitters to broadcast VLF signals to an underground mobile receiver which uses methods such as triangulation and trilateration to obtain a position solution. The second scheme consists of using above-ground reference receivers along with an underground mobile receiver to form time-difference- of-arrival measurements of incoming VLF signals of opportunity, such as lightning strike emissions, to calculate a position solution. The objective of this thesis is to develop positioning algorithms and use simulations as a tool to characterize the …
Thermally Activated, Variable Blazed Grating For Coherent Beam Steering, Matthew T. Johnson
Thermally Activated, Variable Blazed Grating For Coherent Beam Steering, Matthew T. Johnson
Theses and Dissertations
The ability to perform non-mechanical optical beam steering is of critical importance in laser communication and remote sensing; it is as vital as a phased-array antenna is for RADAR. Directed energy transmission and direction-selective reception increase performance and produce tactical advantage in DoD applications. However, specific geometric features of non-mechanical beam steering devices must be designed in proportion to the wavelength of the monochromatic light to be steered. Also, the ability to handle higher energies by reducing the energy per unit requires large areas of uniform properties on the micrometer scale. These challenges have been addressed in the past using …
Material Characterization Improvement In High Temperature Rectangle Waveguide Measurements, Eric A. Buschelman
Material Characterization Improvement In High Temperature Rectangle Waveguide Measurements, Eric A. Buschelman
Theses and Dissertations
This research presents a method by which electromagnetic characterization of materials in a partially filled waveguide can be accurately performed. Higher order modes are excited by the geometry, which are not accounted for in most algorithms. A correction must consider the power transmitted by higher-order modes. Modal solutions, using reference plane independence, for a single top air gap between the material sample and the waveguide wall, are also presented. Characterization is performed on samples of acrylic and rubberized magnetic radar absorbing material. Calculation of the complex permittivity and permeability of shielding material, within 10% of the true value, was achieved …
Nonlinear Time-Variant Response In An Avalanche Photodiode Array Based Laser Detection And Ranging System, Michael D. Seal
Nonlinear Time-Variant Response In An Avalanche Photodiode Array Based Laser Detection And Ranging System, Michael D. Seal
Theses and Dissertations
This research effort identifies and models the nonlinear time-variant behavior exhibited by an avalanche photodiode (APD) array based Laser Ranging and Detection (LADAR) system. Based on the original Linear Time-Invariant (LTI) model, the evolution of error in the LADAR signal is examined sequentially from the outgoing pulse through signal digitization. This error evolution shows that the LTI model does not contain a mechanism for causing the observed signal deviations or the failure to meet the Cramer-Rao lower bound for range accuracy. A nonlinear time-variant model is developed based on the interactions of the avalanche photodiodes in the array with the …
Propagation Of Ultrashort Laser Pulses Through Water, Jianchao Li, Dennis R. Alexander, Haifeng Zhang, Ufuk Parali, David Doerr, John Clark Bruce Iii, Hao Wang
Propagation Of Ultrashort Laser Pulses Through Water, Jianchao Li, Dennis R. Alexander, Haifeng Zhang, Ufuk Parali, David Doerr, John Clark Bruce Iii, Hao Wang
Department of Electrical and Computer Engineering: Faculty Publications
In this paper, propagation of ultrashort pulses through a long 3.5 meter water channel was studied. Of particular interest was the attenuation of the beam at various lengths along the variable path length and to find an explanation of why the attenuation deviates from typical Beer Lambert law around 3 meters for ultrashort laser pulse transmission. Laser pulses of 10 fs at 75 MHz, 100 fs at 80 MHz and 300 fs at 1 KHz were employed to investigate the effects of pulse duration, spectrum and repetition rate on the attenuation after propagating through water up to 3 meters. Stretched …
Optimization Of Zonal Wavefront Estimation And Curvature Measurements, Weiyao Zou
Optimization Of Zonal Wavefront Estimation And Curvature Measurements, Weiyao Zou
Electronic Theses and Dissertations
Optical testing in adverse environments, ophthalmology and applications where characterization by curvature is leveraged all have a common goal: accurately estimate wavefront shape. This dissertation investigates wavefront sensing techniques as applied to optical testing based on gradient and curvature measurements. Wavefront sensing involves the ability to accurately estimate shape over any aperture geometry, which requires establishing a sampling grid and estimation scheme, quantifying estimation errors caused by measurement noise propagation, and designing an instrument with sufficient accuracy and sensitivity for the application. Starting with gradient-based wavefront sensing, a zonal least-squares wavefront estimation algorithm for any irregular pupil shape and size …
All-Optical Regeneration For Phase-Shift Keyed Optical Communication Systems, Kevin Croussore
All-Optical Regeneration For Phase-Shift Keyed Optical Communication Systems, Kevin Croussore
Electronic Theses and Dissertations
All-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase-preserving amplitude regeneration, phase regeneration, and phase-regenerative wavelength conversion are analyzed and demonstrated experimentally. The single-pump phase-conjugation process was used to regenerate RZ-DPSK pulse amplitudes with different input noise distributions, and the impact on output phase …
Macrobending Fiber Loss Filter, Ratiometric Wavelength Measurement And Application, Qian Wang, Ginu Rajan, Gerald Farrell, Pengfei Wang, Yuliya Semenova, Thomas Freir
Macrobending Fiber Loss Filter, Ratiometric Wavelength Measurement And Application, Qian Wang, Ginu Rajan, Gerald Farrell, Pengfei Wang, Yuliya Semenova, Thomas Freir
Articles
A macrobending standard single-mode fibre (SMF28) is optimized as an edge filter, with the optimal bending radius and length determined according to the bend loss and polarization sensitivity of the bending fibre. An all-fibre ratiometric wavelength system is built and calibrated. The system's accuracy and resolution is discussed with the influence of noise of input signal and photodetectors. Finally, the ratiometric system is employed for the demodulation of FBG strain sensing.
Effects Of Polarization And Coherence On The Propagation And The Detection Of Stochastic Electromagnetic Beams, Mohamed Fouad Salem
Effects Of Polarization And Coherence On The Propagation And The Detection Of Stochastic Electromagnetic Beams, Mohamed Fouad Salem
Electronic Theses and Dissertations
Most of the physically realizable optical sources are radiating in a random manner given the random nature of the radiation of a large number of atoms that constitute the source. Besides, a lot of natural and synthetic materials are fluctuating randomly. Hence, the optical fields that one encounters, in most of the applications are fluctuating and must be treated using random or stochastic functions. Within the framework of the scalar-coherence theory, one can describe changes of the properties of any stochastic field such as the spectral density and the spectral degree of coherence on propagation in any linear medium, deterministic …
Including Effects Of Microstructure And Anisotropy In Theoretical Models Describing Hysteresis Of Ferromagnetic Materials, H. Hauser, Y. Melikhov, David C. Jiles
Including Effects Of Microstructure And Anisotropy In Theoretical Models Describing Hysteresis Of Ferromagnetic Materials, H. Hauser, Y. Melikhov, David C. Jiles
David C. Jiles
Two recent theoreticalhysteresis models (Jiles-Atherton model and energetic model) are examined with respect to their capability to describe the dependence of the magnetization on magnetic field, microstructure, and anisotropy. It is shown that the classical Rayleigh law for the behavior of magnetization at low fields and the Stoner-Wohlfarth theory of domain magnetization rotation in noninteracting magnetic single domain particles can be considered as limiting cases of a more general theoretical treatment of hysteresis in ferromagnetism.
Atmospheric Turbulence Compensation Of Point Source Images Using Asynchronous Stochastic Parallel Gradient Descent Technique On Amos 3.6 M Telescope, Mikhail Vorontsov, Jim F. Riker, Gary W. Carhart, Venkata S. Rao Gudimetla, Leonid A. Beresnev, Thomas Weyrauch
Atmospheric Turbulence Compensation Of Point Source Images Using Asynchronous Stochastic Parallel Gradient Descent Technique On Amos 3.6 M Telescope, Mikhail Vorontsov, Jim F. Riker, Gary W. Carhart, Venkata S. Rao Gudimetla, Leonid A. Beresnev, Thomas Weyrauch
Electrical and Computer Engineering Faculty Publications
The Stochastic Parallel Gradient Descent Technique-based Adaptive Optics (SPGD-AO) system described in this presentation does not use a conventional wavefront sensor. It uses a metric signal collected by a single pixel detector placed behind a pinhole in the image plane to drive three deformable mirrors (DMs). The system is designed to compensate the image for turbulence effects. The theory behind this method is described in detail in [1]. However this technique, while widely simulated and tested in the laboratory, was not yet verified in astronomical field site experiments. During the month of May 2007, a series of experiments with SPGD-AO …
Adaptive Optics Performance Over Long Horizontal Paths: Aperture Effects In Multi-Conjugate Adaptive Optical Systems, Miao Yu, Mikhail Vorontsov, Svetlana Lachinova, Jim F. Riker, Venkata S. Rao Gudimetla
Adaptive Optics Performance Over Long Horizontal Paths: Aperture Effects In Multi-Conjugate Adaptive Optical Systems, Miao Yu, Mikhail Vorontsov, Svetlana Lachinova, Jim F. Riker, Venkata S. Rao Gudimetla
Electrical and Computer Engineering Faculty Publications
We analyze various scenarios of the aperture effects in adaptive optical receiver-type systems when inhomogeneities of the wave propagation medium are distributed over long horizontal propagation path, or localized in a few thin layers remotely located from the receiver telescope pupil. Phase aberration compensation is performed using closed-loop control architectures based on phase conjugation and decoupled stochastic parallel gradient descent (DSPGD) control algorithms. Both receiver system aperture diffraction effects and the impact of wave-front corrector position on phase aberration compensation efficiency are analyzed for adaptive systems with single or multiple wave-front correctors.
Thermal Transient Flow Rate Sensor For High Temperature Liquid Metal Cooled Nuclear Reactor, Yingtao Jiang, Jian Ma, Rohit Reddy Saddi
Thermal Transient Flow Rate Sensor For High Temperature Liquid Metal Cooled Nuclear Reactor, Yingtao Jiang, Jian Ma, Rohit Reddy Saddi
Mechanical Engineering Faculty Research
In nuclear power plants and accelerator driven system (ADS) for nuclear waste treatment, it is important to monitor the coolant flow rate in the reactor core and pipe-line. In such a strong irradiation, high pressure and temperature environment, no accurate local flow measurement technique is readily available. Electromagnetic (EM) flow meter is popular in low temperature application as it is a non-intrusive technology. However, additional voltage will be produced due to temperature, flow, pressure, the chemical properties of the liquid metal and surface condition of the steel walls. In addition, the non-definite wetting behavior of liquid lead-bismuth to the electrically …
Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton
Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton
Publications
The use of fiber-reinforced polymer (FRP) composites to strengthen existing civil infrastructure is expanding rapidly. Many FRP systems used to strengthen reinforced concrete are applied using a wet lay-up method in which dry fibers are saturated on site and then applied to the surface. This research investigated using infrared thermography (IRT) as a nondestructive evaluation (NDE) tool for detecting air voids and epoxy-filled holes in FRP systems bonded to a concrete substrate. Four small-scale specimens with FRP thicknesses ranging from 1 to 4 mm (0.04 to 0.16 in.) containing fabricated defects were constructed and inspected in a laboratory setting. Three …
Study Of Soliton Stabilization In D+1 Dimensions Using Novel Analytical And Numerical Techniques, George Nehmetallah, Partha P. Banerjee
Study Of Soliton Stabilization In D+1 Dimensions Using Novel Analytical And Numerical Techniques, George Nehmetallah, Partha P. Banerjee
Electrical and Computer Engineering Faculty Publications
In this Chapter, we provide a brief review of the underlying nonlinear Schrödinger and associated equations that model spatio-temporal propagation in one and higher dimensions in a nonlinear dispersive environment. Particular attention is given to fast adaptive numerical techniques to solve such equations, and in the presence of dispersion and nonlinearity management, saturating nonlinearity and nonparaxiality. A unique variational approach is also outlined which helps in determining the ranges of nonlinearity and dispersion parameters to ensure stable solutions of the nonlinear equations. The propagation of 3+1 dimensional spatio-temporal pulses, or optical bullets is also modeled using a fast adaptive split-step …
Two-Dimensional Guided Mode Resonant Structures For Spectral Filtering Applications, Sakoolkan Boonruang
Two-Dimensional Guided Mode Resonant Structures For Spectral Filtering Applications, Sakoolkan Boonruang
Electronic Theses and Dissertations
Guided mode resonant (GMR) structures are optical devices that consist of a planar waveguide with a periodic structure either imbedded in or on the surface of the structure. The resonance anomaly in GMR structures has many applications as dielectric mirrors, tunable devices, sensors,and narrow spectral band reflection filters. A desirable response from a resonant grating filter normally includes a nearly 100% narrowband resonant spectral reflection (transmission), and a broad angular acceptance at either normal incidence or an oblique angle of incidence. This dissertation is a detailed study of the unique nature of the resonance anomaly in GMR structures with two-dimensional …
Scalable Volumetric Three-Dimensional Up-Conversion Display Medium, Jung-Hyun Cho
Scalable Volumetric Three-Dimensional Up-Conversion Display Medium, Jung-Hyun Cho
Electronic Theses and Dissertations
There are many different techniques to display 3D information. However, not many of them are able to provide sufficient depth cues to the observers to sense or feel the images as real three-dimensional objects. Volumetric three-dimensional displays generate images within a real 3D space, so they provide most of the depth cues automatically. This thesis discusses the basic notions required to understand three-dimensional displays. Also discussed are different techniques used to display 3D information and their advantages and disadvantages as well as their current limitations. Several rare-earth doped fluoride crystals that are excited to emit visible light by sequential two …
High-Speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems, Wangkuen Lee
High-Speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems, Wangkuen Lee
Electronic Theses and Dissertations
1.55-µm high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (>5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied …
Infrared Antenna-Coupled Phased-Array, Christopher Middlebrook
Infrared Antenna-Coupled Phased-Array, Christopher Middlebrook
Electronic Theses and Dissertations
Phased-array antennas are commonplace in the radiofrequency portion of the electromagnetic spectrum. Exploitation of phasing effects between multiple antennas facilitates a wide range of applications, including synthetic-aperture radar, beam forming, and beam scanning. For the first time, the phased addition of multiple dipole antennas is demonstrated in the infrared, at a wavelength of 10.6 micrometers. Coplanar strip lines are used to interconnect the antennas, preserving the phase of the individual contributions. Several different proof-of-concept experiments are performed, using planar antennas fabricated with direct-write electron-beam lithography. Infrared-frequency currents from two dipole antennas are summed together at a common feedpoint and dissipated …
Micro-Optic-Spectral-Spatial-Elements (Mosse), Alok Ajay Mehta
Micro-Optic-Spectral-Spatial-Elements (Mosse), Alok Ajay Mehta
Electronic Theses and Dissertations
Over a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization gratings. The feasibility of fabrication, functionality, and level of integration which these elements can be used in an optical system differentiate which elements are more compatible with certain systems than others. With enabling technologies emerging allowing …
Discrete Surface Solitons, Sergiy Suntsov
Discrete Surface Solitons, Sergiy Suntsov
Electronic Theses and Dissertations
Surface waves exist along the interfaces between two different media and are known to display properties that have no analogue in continuous systems. In years past, they have been the subject of many studies in a diverse collection of scientific disciplines. In optics, one of the mechanisms through which optical surface waves can exist is material nonlinearity. Until recently, most of the activity in this area was focused on interfaces between continuous media but no successful experiments have been reported. However, the growing interest that nonlinear discrete optics has attracted in the last two decades has raised the question of …
Design And Demonstration Of Meanderline Retarders At Infrared Frequencies, Jeffrey Scott Tharp
Design And Demonstration Of Meanderline Retarders At Infrared Frequencies, Jeffrey Scott Tharp
Electronic Theses and Dissertations
Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. …
Hybrid Photonic Signal Processing, Farzan Naseer Ghauri
Hybrid Photonic Signal Processing, Farzan Naseer Ghauri
Electronic Theses and Dissertations
This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an …
Rigorous Analysis Of Wave Guiding And Diffractive Integrated Optical Structures, Andrew Greenwell
Rigorous Analysis Of Wave Guiding And Diffractive Integrated Optical Structures, Andrew Greenwell
Electronic Theses and Dissertations
The realization of wavelength scale and sub-wavelength scale fabrication of integrated optical devices has led to a concurrent need for computational design tools that can accurately model electromagnetic phenomena on these length scales. This dissertation describes the physical, analytical, numerical, and software developments utilized for practical implementation of two particular frequency domain design tools: the modal method for multilayer waveguides and one-dimensional lamellar gratings and the Rigorous Coupled Wave Analysis (RCWA) for 1D, 2D, and 3D periodic optical structures and integrated optical devices. These design tools, including some novel numerical and programming extensions developed during the course of this work, …
High Birefringence Liquid Crystals For Optical Communications, Amanda Jane Parish
High Birefringence Liquid Crystals For Optical Communications, Amanda Jane Parish
Electronic Theses and Dissertations
High birefringence (Δn > 0.4) nematic liquid crystals are particularly attractive for infrared applications because they enable a thinner cell gap to be used for achieving fast response time and improved diffraction efficiency. In this thesis, the mesomorphic and electro‐optic properties of several new fluorinated isothiocyanate (NCS) terphenyl and phenyl tolane single compounds and mixtures are reported. The single compounds demonstrated Δn~0.35‐0.52 in the visible spectral region at room temperature and exhibit relatively low viscosity. It was found that lateral fluorine substitutions and short alkyl chains eliminate smectic phase and lower the melting temperature of the single compounds. However, the consequence …