Electromagnetics and Photonics Commons^™

Topological Wave Insulators: A Review, Farzad Zangeneh-Nejad, Andrea Alù, Romain Fleury

Advanced Science Research Center

Originally discovered in condensed matter systems, topological insulators (TIs) have been ubiquitously extended to various fields of classical wave physics including photonics, phononics, acoustics, mechanics, and microwaves. In the bulk, like any other insulator, electronic TIs exhibit an excessively high resistance to the flow of mobile charges, prohibiting metallic conduction. On their surface, however, they support one-way conductive states with inherent protection against certain types of disorder and defects, defying the common physical wisdom of electronic transport in presence of impurities. When transposed to classical waves, TIs open a wealth of exciting engineering-oriented applications, such as robust routing, lasing, signal …

An Emi Characterization And Modeling Study For Consumer Electronics And Integrated Circuits, Chunyu Wu

Doctoral Dissertations

“As internet-of-things (IoT) applications surge, wireless connectivity becomes an essential part of the network. Smart home, one of the most promising application scenarios of IoT, will improve our life quality enormously. However, electromagnetic interference (EMI) to the receiving antenna, either from another electronic product or from a module/an integrated circuit(IC) inside the same wireless device, will degrade the performance of wireless connectivity, thus influencing the user experience. Characterization and modeling of the EMI become increasingly important.

In the first part, an improved method to extract equivalent dipoles from magnitude- only electromagnetic-field data based on the genetic algorithm and back-and-forth iteration …

Flux Expulsion In Niobium Superconducting Radio-Frequency Cavities Of Different Purity And Essential Contributions To The Flux Sensitivity, P. Dhakal, Gianluigi Ciovati, Alex Gurevich

Physics Faculty Publications

Magnetic flux trapped during the cooldown of superconducting radio-frequency cavities through the transition temperature due to incomplete Meissner state is known to be a significant source of radio-frequency losses. The sensitivity of flux trapping depends on the distribution and the type of defects and impurities which pin vortices, as well as the cooldown dynamics when the cavity transitions from a normal to superconducting state. Here we present the results of measurements of the flux trapping sensitivity on 1.3 GHz elliptical cavities made from large-grain niobium with different purity for different cooldown dynamics and surface treatments. The results show that lower …

Performance Enhancement And Characterization Of An Electromagnetic Railgun, Paul M. Gilles

Master's Theses

Collision with orbital debris poses a serious threat to spacecraft and astronauts. Hypervelocity impacts resulting from collisions mean that objects with a mass less than 1g can cause mission-ending damage to spacecraft. A means of shielding spacecraft against collisions is necessary. A means of testing candidate shielding methods for their efficacy in mitigating hypervelocity impacts is therefore also necessary. Cal Poly’s Electromagnetic Railgun was designed with the goal of creating a laboratory system capable of simulating hypervelocity (≥ 3 km/s) impacts. Due to several factors, the system was not previously capable of high-velocity (≥ 1 km/s) tests. A deficient projectile …

High Frequency Ltcc Based Planar Transformer, Adithya Venkatanarayanan

Graduate Theses and Dissertations

As we move towards high power and higher frequency related technology, conventional wire-wound magnetics have their own limitations which has led path to the development of planar based magnetic materials. Nowadays more planar magnetic technology has been employed because it is easier to fabricate them. The planar magnetic is a transformer or an inductor that replaces the wire-wound transformer or inductors which generally uses copper wires. One of the main reasons why we move to planar magnetic technology is its operation at higher frequency which provides higher power density. This study explains in detail about the design and fabrication of …

Sparsity Constrained Regression For High-Speed Signal Integrity Modeling, Jiacheng Zhuo, Jiayi He, Zurab Kiguradze, Bhyrav Mutnury, James Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

High-speed signal integrity (SI) modeling usually involves modeling non-linear subsystems. Traditional approaches like response surface modeling (RSM), artificial neural networks (ANN) and support vector machine (SVM) suffer from two major issues. Either they don't scale well when the number of dimensions or variables increase in the non-linear model, or they are sensitive to the initial training data used to create the models. For example: RSM approach requires large design of experiments (DoE) when the number of variables increase. With ANN, the designer has to spend a lot of time tuning or optimizing the hyperparameters. In this paper, a new approach …

Bayesian Optimization For High-Speed Channel Equalization, Zurab Kiguradze, Nana Dikhaminjia, Mikheil Tsiklauri, Jiayi He, Bhyrav Mutnury, Arun Chada, James Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Equalization methods are used to recover the signal attenuated by channel loss. Different optimization algorithms are applied to find the best tap coefficients for each equalization that will improve eye opening and reduce bit error rate. The goal function for most equalization optimization algorithms is to reduce the difference between input and output signals, which is a linear optimization problem and can be solved relatively easily. This indirectly will increase eye height and improve eye diagram. Directly optimizing eye height is a non-linear problem and cannot be solved with analytical method. We are proposing FFE and DFE combined equalization optimization …

Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo

Graduate Theses and Dissertations

Noble metal nanoparticles and two-dimensional (2D) transition metal dichalcogenide (TMD) crystals offer unique optical and electronic properties that include strong exciton binding, spin-orbital coupling, and localized surface plasmon resonance. Controlling these properties at high spatiotemporal resolution can support emerging optoelectronic coupling and enhanced optical features. Excitation dynamics of these optical properties on physicochemically bonded mono- and few-layer TMD crystals with metal nanocrystals and two overlapping spherical metal nanocrystals were examined by concurrently (i) DDA simulations and (ii) far-field optical transmission UV-vis spectroscopic measurements. Initially, a novel and scalable method to unsettle van der Waals bonds in bulk TMDs to prepare …

Exploring Convergence Of Snake Skin-Inspired Texture Designs And Additive Manufacturing For Mechanical Traction, Catherine Sue Tiner

Graduate Theses and Dissertations

This research focuses on the understanding, development, and additive manufacture of a 3D printed snake skin-inspired texture pattern. The design functionalities of snake skin were determined through the study of the snake species Python Regius otherwise known as the ball python. Each scale of a snake has hierarchical texture with hexagonal macro-patterns aligned on the ventral surface of the skin with overriding anisotropic micro textured patterns such as denticulations and fibrils. Using a laser-powder bed fusion (L-PBF) process, 420 stainless steel samples were 3D printed which closely resemble the above described directional texture of natural snake skin. This printed surface …

Synthesis Of Cellulose Nanocrystal-Gold Nanoparticle Hybrid System For Surface Plasmon-Enhanced Property, Mahshid Iraniparast

Graduate Theses and Dissertations

Gold nanoparticles (AuNPs) have been brought to the forefront of various applications, ranging from theranostics, to organic photovoltaics, to biosensing owing to their localized surface plasmon resonance (LSPR) property. However, this property needs to be improved in order to allow for high sensitivity and quantitative detection of biomolecules. Hybrids of AuNPs with low-dielectric cellulose nanocrystal (CNCs) would yield enhancement of the LSPR property, which is driven by the confinement of electron oscillation at their interfaces. This study proposed a seed-mediated growth method to synthesize hybrids of CNCs-AuNPs. Sulfate groups on the surface of CNCs served as the sites for the …

Development Of A Comsol Microdialysis Model, Towards Creation Of Microdialysis On A Chip With Improved Geometries And Recovery, Patrick Pysz

Graduate Theses and Dissertations

Microdialysis (µD) sampling is a diffusion-limited sampling method that has been widely used in different biomedical fields for greater than 35 years. Device calibration for in vivo studies is difficult for current non-steady state analytes of interest correlated with both inflammatory response and microbial signaling molecules (QS); which exist in low ng/mL to pg/mL with molecular weights over a wide range of 170 Da to 70 kDa. The primary performance metric, relative recovery (RR), relating the collected sample to the extracellular space concentration varies from 10% to 60% per analyte even under controlled bench-top conditions. Innovations in microdialysis device design …

Integrated Chirped-Grating Spectrometer-On-A-Chip, Shima Nezhadbadeh

Optical Science and Engineering ETDs

In this dissertation we demonstrate a new structure based on waveguide coupling atop a silicon wafer using a chirped grating to provide the dispersion that leads to a high-resolution, compact, fully integrable and CMOS-compatible spectrometer. Light is both analyzed and detected in a single, completely monolithic component which enables realizing a high-resolution portable spectrometer with an extremely compact footprint. The structure is comprised of a SiO₂/Si₃N₄/SiO₂ waveguide on top of a silicon wafer. Grating regions are fabricated on the top cladding of the waveguide. The input light is incident on a chirped grating …

The Challenges Of Low-Energy Secondary Electron Emission Measurement, Matthew J. Vincie

Theses and Dissertations

The phenomena known as secondary electron emission was discovered over a century ago. Yet it remains very difficult to model accurately due to the limited availability of reliable experimental data. With the growing use of computer simulations in hardware development, the need for accurate models has increased. This research focused on determining what factors may be causing measurement discrepancies and methods for increasing the accuracy of measurements. It was found that several assumptions are commonly invoked when these measurements are performed that may not always be consistent with reality. The violation of these assumptions leads to measurement bias that is …

Measurement Of Electron Density And Temperature From Laser-Induced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao, Mark Gragston, Anil K. Patnaik, Paul S. Hsu, Michael B. Shattan

Faculty Publications

Laser-induced plasmas experience Stark broadening and shifts of spectral lines carrying spectral signatures of plasma properties. In this paper, we report time-resolved Stark broadening measurements of a nitrogen triplet emission line at 1–6 bar ambient pressure in a pure nitrogen cell. Electron densities are calculated using the Stark broadening for different pressure conditions, which are shown to linearly increase with pressure. Additionally, using a Boltzmann fit for the triplet, the electron temperature is calculated and shown to decrease with increasing pressure. The rate of plasma cooling is observed to increase with pressure. The reported Stark broadening based plasma diagnostics in …

Unidirectional And Nonreciprocal Nanophotonic Devices Based On Graphene And Magneto-Optical Materials, Vahid Foroughi Nezhad

LSU Doctoral Dissertations

In this dissertation, we first introduce compact tunable spatial mode converters for graphene parallel plate (GPP) waveguides. The converters are reciprocal and based on spatial modulation of graphene’s conductivity. The wavelength of operation of the mode converters is tunable in the mid-infrared wavelength range by adjusting the chemical potential of a strip on one of the graphene layers of the GPP waveguides. We also introduce optical diodes for GPP waveguides based on a spatial mode converter and a coupler, which consists of a single layer of graphene placed in the middle between the two plates of two GPP waveguides. \par …

Nonlinearities And Carrier Dynamics In Refractory Plasmonic Tin Thin Films, Heather George, Jennifer Reed, Manuel R. Ferdinandus, Clayton Devault, Alexei Lagutchev, Augustine Urbas, Theodore B. Norris, Vladimir M. Shalaev, Alexandra Boltasseva, Nathaniel Kinsey

Faculty Publications

Titanium nitride is widely used in plasmonic applications, due to its robustness and optical properties which resemble those of gold. Despite this interest, the nonlinear properties have only recently begun to be investigated. In this work, beam deflection and non-degenerate femtosecond pump-probe spectroscopy (800 nm pump and 650 nm probe) were used to measure the real and imaginary transient nonlinear response of 30-nm-thick TiN films on sapphire and fused silica in the metallic region governed by Fermi-smearing nonlinearities. In contrast to other metals, it is found that TiN exhibits non-instantaneous positive refraction and reverse saturable absorption whose relaxation is dominated …

Nondestructive Electromagnetic Characterization Of Perfect-Electric-Conductor-Backed Uniaxial Materials, Adam L. Brooks

Theses and Dissertations

As the use of anisotropic materials in electromagnetic applications continues to proliferate, it becomes increasingly important to develop non-destructive evaluation methods for those materials in their installed configuration. In many applications, these materials are permanently affixed onto conducting bodies to reduce unwanted reflections, making it impossible to collect S₂₁ or S₁₂ transmission measurements as used in many techniques based on the well-known Nicolson-Ross-Weir algorithm. It also makes it impractical to reorient the sample to collect orthogonal measurements aligned with the optical axes of the anisotropic material. The goal of this research is to develop a two-reflection coefficient measurement …

Discontinuous Galerkin Vs. Ie Method For Electromagnetic Scattering From Composite Metallic And Dielectric Structures, Y.-Y. Zhu, Q.-M. Cai, R. Zhang, X. Cao, Y.-W. Zhao, B. Gao, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an efficient volume surface integral equation (VSIE) method with nonconformal discretization is developed for the analysis of electromagnetic scattering from composite metallic and dielectric (CMD) structures. This VSIE scheme utilizes curved tetrahedral (triangular) elements for volume (surface) modeling and the associated CRWG (CSWG) basis functions for volume current (surface) current modeling. Further, a discontinuous Galerkin (DG) volume integral equation (VIE) method and a DG surface integral equation (SIE) approach are adopted for dielectric and metallic parts, respectively, which allow both conformal and nonconformal volume/surface discretization improving meshing flexibility considerably. Numerical results are provided to demonstrate the accuracy, …

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace

Theses and Dissertations

Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre and post irradiation. …

Near-Field Effects On Partially Coherent Light Scattered By An Aperture, Milo W. Hyde Iv, Michael J. Havrilla

Faculty Publications

We investigate how the near field affects partially coherent light scattered from an aperture in an opaque screen. Prior work on this subject has focused on the role of surface plasmons, and how they affect spatial coherence is well documented. Here, we consider other near-field effects that might impact spatial coherence. We do this by examining the statistics of the near-zone field scattered from an aperture in a perfect electric conductor plane—a structure that does not support surface plasmons. We derive the near-field statistics (in particular, cross-spectral density functions) by applying electromagnetic equivalence theorems and the Method of Moments. We …