Electromagnetics and Photonics Commons^™

Fundamental Properties Of Metallic Nanolasers, William Hayenga

Electronic Theses and Dissertations

The last two decades have witnessed tremendous advancements in the area of nanophotonics and plasmonics, which has helped propel the development of integrated photonic sources. Of central importance to such circuits is compact, scalable, low threshold, and efficient coherent sources that can be driven at high modulation frequencies. In this regard, metallic nanolasers offer a unique platform. Their introduction has enabled confinement of light at a subwavelength scale and the ultra-small size of the modes afforded by these structures allows for cavity enhancing effects that can help facilitate thresholdless lasing and large direct modulation bandwidths. In this report, I present …

Processing Of Advanced Infrared Materials, Daniel Mcgill

Electronic Theses and Dissertations

Infrared transparent glassy and crystalline materials often have unique and complex processing requirements but are an important class of materials for such applications as optical windows, lenses, waveplates, polarizers and beam splitters. This thesis investigates two specific materials, one amorphous and one crystalline, that are candidates for use in the short and midwave-infrared and mid and longwave infrared, respectively. It is demonstrated that an innovative uniaxial sintering process, which uses a sacrificial pressure-transmitting medium, can be used to fully densify a 70TeO2-20WO3-10La2O3 (TWL) glass powder. The characteristics of the sintered TWL glass is compared to that of a parent glass …

Active Recall Networks For Multiperspectivity Learning Through Shared Latent Space Optimization, Theus Aspiras, Ruixu Liu, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

Given that there are numerous amounts of unlabeled data available for usage in training neural networks, it is desirable to implement a neural network architecture and training paradigm to maximize the ability of the latent space representation. Through multiple perspectives of the latent space using adversarial learning and autoencoding, data requirements can be reduced, which improves learning ability across domains. The entire goal of the proposed work is not to train exhaustively, but to train with multiperspectivity. We propose a new neural network architecture called Active Recall Network (ARN) for learning with less labels by optimizing the latent space. This …

Deep Temporal Convolutional Networks For Short-Term Traffic Flow Forecasting, Wentian Zhao, Yanyun Gao, Tingxiang Ji, Xili Wan, Feng Ye, Guangwei Bai

Electrical and Computer Engineering Faculty Publications

To reduce the increasingly congestion in cities, it is essential for intelligent transportation system (ITS) to accurately forecast the short-term traffic flow to identify the potential congestion sites. In recent years, the emerging deep learning method has been introduced to design traffic flow predictors, such as recurrent neural network (RNN) and long short-term memory (LSTM), which has demonstrated its promising results. In this paper, different from existing work, we study the temporal convolutional network (TCN) and propose a deep learning framework based on TCN model for short-term city-wide traffic forecast to accurately capture the temporal and spatial evolution of traffic …

Non-Invasive Microwave And Millimeter Wave Reflectometry And Imaging For Human Skin Diagnosis And Materials Characterization, Yuan Gao

Doctoral Dissertations

"Microwave and millimeter wave reflectometry and synthetic aperture radar (SAR) imaging techniques have been successfully applied in many applications, such as nondestructive testing and evaluation (NDT&E), security inspection and medical diagnosis. In this dissertation, the feasibility of using microwave and millimeter reflectometry and SAR imaging for burn diagnosis is investigated through both simulations and measurements, with promising results. To correctly model the interaction between electromagnetic waves and skin, the proper knowledge of the complex permittivity of healthy skin is critically important. To this end, the common used measurement methods for in vivo skin complex permittivity are reviewed and analyzed in …

High Performance Liquid Crystal Devices For Augmented Reality And Virtual Reality, Md Javed Rouf Talukder

Electronic Theses and Dissertations

See-through augmented reality and virtual reality displays are emerging due to their widespread applications in education, engineering design, medical, retail, transportation, automotive, aerospace, gaming, and entertainment. For augmented reality and virtual reality displays, high-resolution density, high luminance, fast response time and high ambient contrast ratio are critically needed. High-resolution density helps eliminate the screen-door effect, high luminance and fast response time enable low duty ratio operation, which plays a key role for suppressing image blurs. A dimmer placed in front of AR display helps to control the incident background light, which in turn improves the image contrast. In this dissertation, …

Imaging Through Glass-Air Anderson Localizing Optical Fiber, Jian Zhao

Electronic Theses and Dissertations

The fiber-optic imaging system enables imaging deeply into hollow tissue tracts or organs of biological objects in a minimally invasive way, which are inaccessible to conventional microscopy. It is the key technology to visualize biological objects in biomedical research and clinical applications. The fiber-optic imaging system should be able to deliver a high-quality image to resolve the details of cell morphology in vivo and in real time with a miniaturized imaging unit. It also has to be insensitive to environmental perturbations, such as mechanical bending or temperature variations. Besides, both coherent and incoherent light sources should be compatible with the …

Novel Solid State Lasers Based On Volume Bragg Gratings, Evan Hale

Electronic Theses and Dissertations

Since their invention in 1960, lasers have revolutionized modern technology, and tremendous amounts of innovation and development has gone into advancing their properties and efficiencies. This dissertation reports on further innovations by presenting novel solid state laser systems based on the volume Bragg gratings (VBGs) and the newly developed holographic phase mask (HPMs) for brightness enhancement, dual wavelength operation, and mode conversion. First, a new optical element was created by pairing the HPM with two surface gratings creating an achromatic holographic phase mask. This new optical device successfully performed transverse mode conversion of multiple narrow line laser sources operating from …

High-Dynamic-Range Foveated Near-Eye Display System, Guanjun Tan

Electronic Theses and Dissertations

Wearable near-eye display has found widespread applications in education, gaming, entertainment, engineering, military training, and healthcare, just to name a few. However, the visual experience provided by current near-eye displays still falls short to what we can perceive in the real world. Three major challenges remain to be overcome: 1) limited dynamic range in display brightness and contrast, 2) inadequate angular resolution, and 3) vergence-accommodation conflict (VAC) issue. This dissertation is devoted to addressing these three critical issues from both display panel development and optical system design viewpoints. A high-dynamic-range (HDR) display requires both high peak brightness and excellent dark …

Dual Graphene Patch Antenna For Ka Band Satellite Applications, Mohammed Amin Rabah, Mohammed Bekhti

International Journal of Aviation, Aeronautics, and Aerospace

Currently; grapheme offers a new opportunity to use in space technology and this is due to its amazing properties like conductivity, strength, flexibility and transparency which allows us to exploit new generation of ultra-fast nanoscale components; Since future wireless communication techniques are geared towards the use of the high frequency spectrum and many recent research prove this trend. This letter presents a proposal for design of a dual graphene-based antenna to use in new communication techniques in Ka band, where the proposed antenna can work for uplink and dowlink frequencies at same time since it has return loss less then …

Modeling Land Subsidence Using Insar And Airborne Electromagnetic Data: Dataset, Ryan G. Smith, R. Knight

Research Data

Supporting dataset for article published in Water Resources Research, Volume 55, Issue 4, pages 2801-2819

Recurrent Residual U-Net For Medical Image Segmentation, Md Zahangir Alom, Christopher Yakopcic, Mahmudul Hasan, Tarek M. Taha, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

Deep learning (DL)-based semantic segmentation methods have been providing state-of-the-art performance in the past few years. More specifically, these techniques have been successfully applied in medical image classification, segmentation, and detection tasks. One DL technique, U-Net, has become one of the most popular for these applications. We propose a recurrent U-Net model and a recurrent residual U-Net model, which are named RU-Net and R2U-Net, respectively. The proposed models utilize the power of U-Net, residual networks, and recurrent convolutional neural networks. There are several advantages to using these proposed architectures for segmentation tasks. First, a residual unit helps when training deep …

A Survey Of Techniques For Mobile Service Encrypted Traffic Classification Using Deep Learning, Pan Wang, Xuejiao Chen, Feng Ye, Zhixin Sun

Electrical and Computer Engineering Faculty Publications

The rapid adoption of mobile devices has dramatically changed the access to various net- working services and led to the explosion of mobile service traffic. Mobile service traffic classification has been a crucial task that attracts strong interest in mobile network management and security as well as machine learning communities for past decades. However, with more and more adoptions of encryption over mobile services, it brings a lot of challenges about mobile traffic classification. Although classical machine learning approaches can solve many issues that port and payload-based methods cannot solve, it still has some limitations, such as time-consuming, costly handcrafted …

Unified Probe Launch Pattern Design And Methodology Of Differential Probe Characterization, Han Deng

Masters Theses

"Differential probe is wildly used in the signal integrity area to do the accuracy signal measurement in frequency domain or time domain. Comparing with traditional SMA connector measurement, the probe measurement has several advantages such as the high flexibility and measurement efficiency. Nevertheless, the probe has some disadvantages such as multiple design patterns and the difficulty of fast landing. In this thesis, a unified probe landing pattern is provided to solve the con of probes and a probe testing fixture is designed for characterize probe and extract the probe model.

In the first portion, a unified differential probe launching pattern …

Coupling Path Visualization Based On Reciprocity Theorem, Yang Zhong

Masters Theses

"A new method to visualize coupling path is proposed to help solve EMI problems. Based on the reciprocity theorem and the concept of reaction, coupling coefficient (CC) is defined to characterize coupling power density. For two-port networks, surface integral of CC can represent coupled voltage on the open-circuited port or coupled power on the loaded port. For dipole-moment based systems, surface integral of CC can represent coupled field components. The calculated CC should be a complex scalar at each point. By properly adjusting the excitation phases, the imaginary part of surface integral of CC will be zero and thus can …

Practical Methods For Source Separation In Emc Measurements, Yuanzhuo Liu

Masters Theses

"Electromagnetic emission is critical in the electronic industry with the rapid growth of the development of the electronic device. To identify the emission from the multipule sources, two methods are proposed in the near field scan and total radiated power measurement respectively.

The first method can be applied in the measurement of the field generated by multiple non-correlated sources. The contribution of each source is determined using a blind source separation (BSS) technique. The measurements are performed using one scanning probe and stationary reference probes, avoiding the need to measure the spatial correlations of the random field. The resolving result …

Near-Field Scanning Based Shielding Effectiveness Extraction For Board Level Shielding Cans, Harsh Shrivastav

Masters Theses

"The conventional definition of shielding effectiveness is well suited for calculating electromagnetic shielding in the far-field. However, in the near field, shielding effectiveness calculation is not so straight forward. In radio frequency interference problems, most of the field coupling occurs in near field. Having a well-defined method to calculate near-field shielding effectiveness is important for estimating the suppression of radio frequency interference using the shield cans. In this research, a method to extract the shielding effectiveness of board level shielding cans using near field scanning is developed. Shielding effectiveness is defined by modelling the shielded noise source as equivalent dipole …

Experimental Characterization Of Common-Mode Sources For Prediction Of System Level Common-Mode Current On Cable Harnesses, Sameer Sudha Arun Walunj

Masters Theses

"Common-mode current on cable harnesses is often the primary source of radiated emissions below several hundred megahertz. It is difficult, however, to estimate common-mode currents that will occur in a system from component level tests because the common-mode impedances are different in the system. Research presents two methods for using simple component level tests to estimate equivalent common-mode source voltages and source impedances responsible for generating common-mode current. Key to these methods is assuming the harness can be represented with two transmission lines, one terminated with a short and one with an open. Equivalent sources are predicted for those circuits …

Estimating Electromagnetic Emissions From A Site Installation With Multiple Racks Of Server Equipment, Ze Sun

Masters Theses

“There are hundreds, sometimes even thousands, of servers working simultaneously inside a data center. Their radiation can be a problem and cause EMI issues. However, it is not feasible to perform full-wave simulation of these racks because of the large electric size of the model. In this thesis, an algorithm is proposed to predict the emission form rack array. The equivalent dipole source is extracted from EMI measurement data of a single rack and used as the radiation source in the multiple rack model. The coupling between racks cannot be ignored, but through the simulation, it is also found that …

Evaluation Of Wireless Router Antennas And 3d-Printed Simulated Antenna Designs, Bibek Kattel

Electronic Theses and Dissertations

As the size of the electronics devices is decreasing the overall size of the antenna inside them is also decreasing. As the antenna size becomes smaller it is more difficult to manufacture them with the process of traditional manufacturing that uses the subtractive method to manufacture a structure. This is where additive manufacturing has an edge on traditional manufacturing. The use of this method to manufacture antennas has been discussed in this thesis. Five antennas from a wireless router are evaluated by modeling them in CST Microwave Studio and are modified so that they can be manufactured with 3D printing. …

Automation Of Data Collection From An Anechoic Chamber, Thomas S. Garner

Electronic Theses and Dissertations

This paper describes the calibration methods and the process that is used on the Ole Miss electrical engineering anechoic chamber. Furthermore the MATLAB code that operates the anechoic chamber has been updated to collect sweep data. The GUI also now includes a tab for calibration giving the user the ability to calibrate for their desired frequency range for when there is not sufficient calibration data already available.

Mode Coupling In Space-Division Multiplexed Systems, Huiyuan Liu

Electronic Theses and Dissertations

Even though fiber-optic communication systems have been engineered to nearly approach the Shannon capacity limit, they still cannot meet the exponentially-growing bandwidth demand of the Internet. Space-division multiplexing (SDM) has attracted considerable attention in recent years due to its potential to address this capacity crunch. In SDM, the transmission channels support more than one spatial mode, each of which can provide the same capacity as a single-mode fiber. To make SDM practical, crosstalk among modes must be effectively managed. This dissertation presents three techniques for crosstalk management for SDM. In some cases such as intra-datacenter interconnects, even though mode crosstalk …

Optical And Electrical Analysis Of Zno/Znte Micropillar Solar Cells, Sadia Binte Sohid

Master’s Theses

The prime focus of the energy-research community in recent times has been replacing fossil fuels with renewable energy. Therefore, photovoltaic research areas are rapidly expanding in this era. The purpose of this work is to compare three different structural ZnO/ZnTe solar cell types (planar, axial micropillar and radial micropillar). The best optical and electrical performance has been obtained by the radial junction (core-shell) ZnO/ZnTe micropillar solar cell due to its pillar structure and radial junction. The unique advantage of the radial junction micropillar is that the angle of the incident light and the carrier collection is orthogonal. Therefore, the pillar …

Formulation And Implementation Of Iterative Method For Generating Spatially-Variant Lattices, Manuel Fernando Martinez

Open Access Theses & Dissertations

The use of a matrix-free, memory-efficient approach to generate large-scale spatially variant lattices (SVL) was explored. A matrix-free iterative SVL generation algorithm was formulated and then implemented with a tremendous memory reduction observed. The algorithm consists of solving first-order central finite-differences along the entirety of the problem space point-by-point to obtain the grating phase function Φ(𝑠⃗) to which all desired spatially variant lattice properties are applied to. The algorithm was studied to identify key areas of data and task parallelism to exploit in heterogeneous computing systems consisting of clusters of central processing units (CPU) and graphics processing units (GPU) combinations. …

Broadband Mid-Infrared Frequency Combs Generated Via Frequency Division, Qitian Ru

Electronic Theses and Dissertations

Frequency combs have revolutionized metrology and demonstrated numerous applications in science and technology. Combs operating in the mid-infrared region could be beneficial for molecular spectroscopy for several reasons. First, numerous molecules have their spectroscopic signatures in this region. Furthermore, the atmospheric window (3-5μm and 8-14μm) is located here. Additionally, a mid-infrared frequency comb could be employed as a diagnostic tool for the many components of human breath, as well as for detection of harmful gases and contaminants in the atmosphere. In this thesis, I used synchronously pumped subharmonic optical parametric oscillators (OPOs) operating at degeneracy to produce ultra-broadband outputs near …

Artificial Magnetism And Topological Phenomena In Optics, Midya Parto

Electronic Theses and Dissertations

Recent years have witnessed intense research activities to effectively control the flow of photons using various classes of optical structures such as photonic crystals and metamaterials. In this regard, optics has benefited from concepts in condensed matter and solid-state physics, where similar problems concerning electronic wavefunctions arise. An important example of such correspondence is associated with the photon dynamics under the effect of an artificial magnetic field. This is especially important since photons, as neutral bosons, do not inherently interact with magnetic fields. One way to mitigate this issue is to exploit magneto-optical materials. However, as is well known, using …

Fast, Sparse Matrix Factorization And Matrix Algebra Via Random Sampling For Integral Equation Formulations In Electromagnetics, Owen Tanner Wilkerson

Theses and Dissertations--Electrical and Computer Engineering

Many systems designed by electrical & computer engineers rely on electromagnetic (EM) signals to transmit, receive, and extract either information or energy. In many cases, these systems are large and complex. Their accurate, cost-effective design requires high-fidelity computer modeling of the underlying EM field/material interaction problem in order to find a design with acceptable system performance. This modeling is accomplished by projecting the governing Maxwell equations onto finite dimensional subspaces, which results in a large matrix equation representation (Zx = b) of the EM problem. In the case of integral equation-based formulations of EM problems, the M-by-N system matrix, Z, …

Optimum Design Of Axial Flux Pm Machines Based On Electromagnetic 3d Fea, Narges Taran

Theses and Dissertations--Electrical and Computer Engineering

Axial flux permanent magnet (AFPM) machines have recently attracted significant attention due to several reasons, such as their specific form factor, potentially higher torque density and lower losses, feasibility of increasing the number of poles, and facilitating innovative machine structures for emerging applications. One such machine design, which has promising, high efficiency particularly at higher speeds, is of the coreless AFPM type and has been studied in the dissertation together with more conventional AFPM topologies that employ a ferromagnetic core.

A challenge in designing coreless AFPM machines is estimating the eddy current losses. This work proposes a new hybrid analytical …

Non-Hermitian And Space-Time Mode Management, Nicholas Nye

Electronic Theses and Dissertations

In the last few years, optics has witnessed the emergence of two fields namely metasurfaces and parity-time (PT) symmetry. Optical metasurfaces are engineered structures that provide unique responses to electromagnetic waves, absent in natural materials. On the other hand, PT symmetry has emerged from quantum mechanics, when a new class of non-Hermitian Hamiltonian quantum systems was shown to have real eigenvalues. In this work, we demonstrate how PT-symmetric diffractive structures are capable of eliminating diffraction orders in specific directions, while maintaining/enhancing the remaining orders. In the second part of this work, we emphasize on supersymmetry (SUSY) and its applications in …

Computational Imaging Systems For High-Speed, Adaptive Sensing Applications, Yangyang Sun

Electronic Theses and Dissertations

Driven by the advances in signal processing and ubiquitous availability of high-speed low-cost computing resources over the past decade, computational imaging has seen the growing interest. Improvements on spatial, temporal, and spectral resolutions have been made with novel designs of imaging systems and optimization methods. However, there are two limitations in computational imaging. 1), Computational imaging requires full knowledge and representation of the imaging system called the forward model to reconstruct the object of interest. This limits the applications in the systems with a parameterized unknown forward model such as range imaging systems. 2), the regularization in the optimization process …