Electromagnetics and Photonics Commons^™

Realization Of Negative Index In Second-Order Dispersive Metamaterials Using Standard Dispersion Models For Electromagnetic Parameters, Tarig A. Algadey, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

In recent work, electromagnetic propagation velocities for plane waves in dispersive metamaterials were calculated assuming frequency dispersion up to the second order. The three velocities were expressed in terms of dispersive coefficients under certain simplifying constraints. Frequency domains were found to exist around resonances where group and phase velocities are in opposition, implying possible negative index behavior.

In this paper, we incorporate in the derived equations physical models (including Debye, Lorentz and Condon) for material dispersion in permittivity, permeability and chirality in order to further examine the consequences of second-order dispersion leading to negative index for practical cases, and also …

Modeling Of Power Spectral Density Of Modified Von Karman Atmospheric Phase Turbulence And Acousto-Optic Chaos Using Scattered Intensity Profiles Over Discrete Time Intervals, Monish Ranjan Chatterjee, Fathi H.A. Mohamed

Electrical and Computer Engineering Faculty Publications

In recent research, propagation of plane electromagnetic (EM) waves through a turbulent medium with modified von Karman phase characteristics was modeled and numerically simulated using transverse planar apertures representing narrow phase turbulence along the propagation path.

The case for extended turbulence was also studied by repeating the planar phase screens multiple times over the propagation path and incorporating diffractive effects via a split-step algorithm. The goal of the research reported here is to examine two random phenomena: (a) atmospheric turbulence due to von Karman-type phase fluctuations, and (b) chaos generated in an acousto-optic (A-O) Bragg cell under hybrid feedback. The …

Numerical Investigation Of The Nonlinear Dynamics Of A Hybrid Acousto-Optic Bragg Cell With A Variable Feedback Gain, Monish Ranjan Chatterjee, Hao Zhou

Electrical and Computer Engineering Faculty Publications

Since around 1979, the operation of an acousto-optic Bragg cell under positive first-order feedback via amplification and delay in the loop has been studied extensively by several groups [1-3]. In recent work, the analysis of the nonlinear dynamics (NLD) of the system was extended to include bistable maps and Lyapunov exponents, and application of the chaos for signal encryption and decryption for uniform plane waves. The present work originated with the problem of a variable photodetector aperture opening relative to the first-order light. This potentially complex problem is simplified by assuming instead a variable feedback gain ( β ~ (t)), …

Nonlocal And Quantum-Tunneling Contributions To Harmonic Generation In Nanostructures: Electron-Cloud-Screening Effects, Michael Scalora, Maria Antonietta Vincenti, Domenico De Ceglia, Joseph W. Haus

Electrical and Computer Engineering Faculty Publications

Our theoretical examination of second- and third-harmonic generation from metal-based nanostructures predicts that nonlocal and quantum-tunneling phenomena can significantly exceed expectations based solely on local, classical electromagnetism. Mindful that the diameter of typical transition-metal atoms is approximately 3 Å, we adopt a theoretical model that treats nanometer-size features and/or subnanometer-size gaps or spacers by taking into account (i) the limits imposed by atomic size to fulfill the requirements of continuum electrodynamics, (ii) spillage of the nearly free electron cloud into the surrounding vacuum, and (iii) the increased probability of quantum tunneling as objects are placed in close proximity.

Our approach …

Quantum Levitation Using Metamaterials, Venkatesh K. Pappakrishnan

Doctoral Dissertations

The emergence of an attractive vacuum force (Casimir force) between two purely dielectric materials can lead to an increase in the friction and the stiction effects in nanoscale devices, resulting in degradation or decreased performance. Thus, it is of high practical importance that the conditions for the reversal of the Casimir force from attractive to repulsive are identified. Although the repulsive Casimir force has been considered for high dielectric materials as an intermediate (between the plates) medium, so far no realistic system has been proposed that can demonstrate quantum levitation with air/vacuum as a host medium. Since air is the …

On Electromagnetic And Quantum Invisibility, Pattabhiraju Chowdary Mundru

Doctoral Dissertations

The principle objective of this dissertation is to investigate the fundamental properties of electromagnetic wave interactions with artificially fabricated materials i.e., metamaterials for application in advanced stealth technology called electromagnetic cloaking. The main goal is to theoretically design a metamaterial shell around an object that completely eliminates the dipolar and higher order multipolar scattering, thus making the object invisible.

In this context, we developed a quasi-effective medium theory that determines the optical properties of multi-layered-composites beyond the quasi-static limit. The proposed theory exactly reproduces the far-field scattering/extinction cross sections through an iterative process in which mode-dependent quasi-effective impedances of the …

State-Of-The-Art Of Metamaterials: Characterization, Realization And Applications, Giuseppe Ruvio, Giovanni Leone

Articles

Metamaterials is a large family of microwave structures that produces interesting ε and μ conditions with huge implications for numerous electromagnetic applications. Following a description of modern techniques to realize epsilon-negative, mu-negative and double-negative metamaterials, this paper explores recent literature on the use of metamaterials in hot research areas such as metamaterial-inspired microwave components, antenna applications and imaging. This contribution is meant to provide an updated overview of complex microwave engineering for the generation of different types of metamaterials and their application in topical electromagnetic scenarios.

Investigation And Optimization Of A New Compact Superconducting Cavity For Deflecting And Crabbing Applications, Subashini Uddika De Silva

Physics Theses & Dissertations

Deflecting and crabbing structures have many applications in current accelerator systems. The primary use of a deflecting cavity is to separate a single beam into multiple beams. A crabbing cavity enables the head-on collision at the interaction point in particle colliders in order to increase the luminosity. The early uses of the deflecting structures have been in the early 1960s: these structures were disk loaded structures operating at room temperature. The crabbing structure which was installed at the NEK electron-positron collider was the first and only operational superconducting cavity of that kind. The most common design of superconducting deflecting and …

The Study Of Electrostatic And Magnetostatic Active Space Radiation Shielding For Deep Space Missions, Leroy A. Fung

Electrical & Computer Engineering Theses & Dissertations

A goal of the National Aeronautics and Space Administration (NASA) has been to develop technologies that will enable deep space explorations. Such missions include a prolonged stay on the Moon and the ability to sustain a long duration of travel time to Mars and beyond. Long-term human exposures to radiation are a crucial concern. Recent research has taken focus on active and passive shielding methods as a way of eliminating the hazard posed by radiation particles. Passive shielding involves the use of materials that has the ability to withstand radiation particles and reduce the dose by stopping or slowing the …

Broadband, Non-Destructive Characterisation Of Pec-Backed Materials Using A Dual-Ridged-Waveguide Probe, Milo W. Hyde Iv, Michael J. Havrilla

Faculty Publications

A new probe which utilises a dual-ridged waveguide to provide broadband, non-destructive (ND) material characterisation measurements of a perfect electric conductor (PEC)-backed material is introduced. The new probe possesses a bandwidth similar to existing coaxial probes and is structurally robust like rectangular waveguide probes. The combinations of these two qualities make it especially attractive for ND inspection/evaluation applications in the field. The theoretical development of the dual-ridged-waveguide probe is discussed. A magnetic field integral equation is derived by applying Love’s equivalence theorem and enforcing the continuity of transverse fields at the dual-ridged-waveguide aperture. The magnetic field integral equation is then …

Footwear And Wrist Communication Links Using 2.4 Ghz And Uwb Antennas, Domenico Gaetano, Patrick Mcevoy, Max Ammann, Colm Brannigan, Louise Keating, Frances Horgan

Articles

It is reported that wearable electronic devices are to be used extensively in the next generation of sensors for sports and health monitoring. The information obtained from sensors on the human body depends on the biological parameters, the measurement rate and the number of sensors. The choice of the wireless protocol depends on the required data rates and on system configurations. The communication link quality is achieved with narrowband technologies such as Bluetooth or Zigbee, provided that the number of sensors is small and data rates are low. However, real-time measurements using wideband channels may also be necessary. This paper …

An Eigenvector-Based Test For Local Stationarity Applied To Array Processing, Jorge Quijano, Lisa M. Zurk

Electrical and Computer Engineering Faculty Publications and Presentations

In sonar array processing, a challenging problem is the estimation of the data covariance matrix in the presence of moving targets in the water column, since the time interval of data local stationarity is limited. This work describes an eigenvector-based method for proper data segmentation into intervals that exhibit local stationarity, providing data-driven higher bounds for the number of snapshots available for computation of time-varying sample covariance matrices. Application of the test is illustrated with simulated data in a horizontal array for the detection of a quiet source in the presence of a loud interferer.

Wideband Balun Design With Ferrite Cores, Paul R. Biggins

Electrical Engineering

This project explores different balun devices in order to develop a balanced to unbalanced transformer that will operate over a wide bandwidth. The balun must operate from at least 1 MHz (or below) to the highest possible frequency. It must have an insertion loss of less than 1 dB under the ideal case with an imbalance of less than 1 dB and 2.5 degrees. Three balun topologies were tested, each built for a 1:1 impedance transformation ratio. Techniques of measuring each balun topology were investigated including gathering accurate data from a three port device with two port instruments and measuring …

Non-Linear Electromechanical System Dynamics, Shathiyakkumar Ganapathy Annadurai

LSU New Orleans Theses and Dissertations

Electromechanical systems dynamics analysis is approached through nonlinear differential equations and further creating a state space model for the system. There are three modules analyzed and validated, first module consists two magnet coupled with a mass spring damper system as a band-pass system, Low-pass equivalent system and Low-pass equivalent system through perturbation analysis. Initially Band Pass frameworks for the systems are formulated considering the relation between the mechanical forcing and current. Using Mathematical tools such as Hilbert transforms, Low-Pass equivalent of the systems are derived. The state equations of the systems are then used to design a working model in …

Data Transfer Using Light, Ryan Thomas Suarez

Computer Engineering

A proof of concerpt for data transmission using light as a medium. Data is transferred by strobing and LED faster than the human eye can detect in an attempt to come up with a more secure alternate to in-building wifi.

A Review Of The Pinned Photodiode For Ccd And Cmos Image Sensors, Eric R. Fossum, Donald B. Hondongwa

Dartmouth Scholarship

The pinned photodiode is the primary photodetector structure used in most CCD and CMOS image sensors. This paper reviews the development, physics, and technology of the pinned photodiode.

Simulation Of A Magnetron Using Discrete Modulated Current Sources, Sulmer A. Fernández Gutierrez

Boise State University Theses and Dissertations

Magnetrons are microwave oscillators and are extensively used for commercial and military applications requiring power levels from the kilowatt to the megawatt range. It has been proposed that the use of gated field emitters with a faceted cathode in place of the conventional thermionic cathode could be used to control the current injection in a magnetron, both temporally and spatially. In this research, this concept is studied using the 2-D particle trajectory simulation Lorentz2E and the 3-D particle-in-cell (PIC) code VORPAL. The magnetron studied is a ten cavity, rising sun magnetron, which can be modeled easily using a 2-D simulation. …

Properties Of Multiferroic Bifeo3 From First Principles, Dovran Rahmedov

Graduate Theses and Dissertations

In this dissertation, a first-principle-based approach is developed to study magnetoelectric effect in multiferoic materials. Such approach has a significant predictive power and might serve as a guide to new experimental works. As we will discuss in the course of this work, it also gives an important insight to the underlying physics behind the experimentally observed phenomena.

We start by applying our method to investigate properties of a generic multiferroic material. We observe how magnetic susceptibility of such materials evolves with temperature and compare this evolution with the characteristic behavior of magnetic susceptibility for pure magnetic systems. Then we focus …

Numerical Examination Of The Nonlinear Dynamics Of A Hybrid Acousto-Optic Bragg Cell With Positive Feedback Under Profiled Beam Propagation, Fares S. Almehmadi, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

In standard weak interaction theory, acousto-optic Bragg analysis typically assumes that the incident light and sound beams are uniform plane waves. Acousto-optic Bragg diffraction with nonuniform profiled input beams is numerically examined under open loop via a transfer function formalism. Unexpected deviations in the first-order diffracted beam from the standard theory are observed for high �� values. These deviations are significant because the corresponding closed-loop system is sensitive to input amplitudes and initial conditions, and the overall impact on the dynamical behavior has not been studied previously in standard analyses. To explore the effect of such nonuniform output profiles on …

Memristor-Based Neuron Circuit And Method For Applying Learning Algorithm In Spice, Christopher Yakopcic, R. Hasan, T.M. Taha, M. Mclean, D. Palmer

Electrical and Computer Engineering Faculty Publications

The learning of nonlinearly separable functions in cascaded memristor crossbar circuits is described and the feasibility of using them to develop low-power neuromorphic processors is demonstrated. This is the first study evaluating the training of memristor crossbars through SPICE simulations. It is important to capture the alternate current paths and wire resistance inherent in these circuits. The simulations show that neural network learning algorithms are able to train in the presence of alternate current paths and wire resistances. The fact that the approach reduces the area by three times and power by two orders of magnitude compared with the existing …