Electromagnetics and photonics Commons^™

Finite-Difference Time-Domain Simulations Of Metamaterials, Zhengwei Hao

Electrical Engineering Dissertations

Metamaterials are periodic structures created by many identical scattering objects which are stationary and small compared to the wavelength of electromagnetic wave applied to it so that when combined with different elements, these materials have the potential to be coupled to the applied electromagnetic wave without modifying the structure. Due to their unusual properties that are not readily available in nature, metamaterials have been drawing significant attentions in many research areas, including theoretical, experimental as well as numerical investigations.

As one of the major computational electromagnetic modeling methods, finite-difference time-domain (FDTD) technique tackles problems by providing a full wave solution ...

Determination Of Ionospheric Current Systems By Measuring The Phase Shift On Amateur Satellite Frequencies, Prajwal M. Kasturi

All Graduate Theses and Dissertations

We investigate the possibility of measuring and using the phase delay of radio frequency transmissions in the amateur satellite band as a method to determine the distribution of currents systems in the ionosphere. The amateur satellite transmissions at 7MHz, 14M Hz, and 144M Hz are low enough for Faraday rotation to cause a significant phase delay on the propagating signals in addition to the phase delay produced by the total electron content (TEC) in the ionosphere. The ionosphere in the E and F regions is modeled as an equivalent thin planar shell of collision free cold plasma 100 km in ...

Thermo-Piezo-Electro-Mechanical Simulation Of Algan (Aluminum Gallium Nitride) / Gan (Gallium Nitride) High Electron Mobility Transistor, Lorin E. Stevens

All Graduate Theses and Dissertations

Due to the current public demand of faster, more powerful, and more reliable electronic devices, research is prolific these days in the area of high electron mobility transistor (HEMT) devices. This is because of their usefulness in RF (radio frequency) and microwave power amplifier applications including microwave vacuum tubes, cellular and personal communications services, and widespread broadband access. Although electrical transistor research has been ongoing since its inception in 1947, the transistor itself continues to evolve and improve much in part because of the many driven researchers and scientists throughout the world who are pushing the limits of what modern ...

Sensitivity Analysis Of Scattering Parameters And Its Applications, Yifan Zhang

Open Access Dissertations and Theses

This thesis contributes significantly to the advanced applications of scattering parameter sensitivity analysis including the design optimization of high-frequency printed structures and in microwave imaging. In both applications, the methods exploit the computational efficiency of the self-adjoint sensitivity analysis (SASA) approach where only one EM simulation suffices to obtain both the responses and their gradients with respect to the optimizable variables.

An S-parameter self-adjoint sensitivity formula for multiport planar structures using the method of moments (MoM) current solution is proposed. It can be easily implemented with existing MoM solvers. The shape perturbation which is required in computing the system-matrix ...

Radio Frequency Direction Of Arrival Determination, Daniel A. Lazar

Undergraduate Research Symposium

This project is focused on implementing source location algorithms to find the direction of arrival of transmitted radio frequency signals on an array of receivers. The MuSIC (multiple signal classification) algorithm is used, as well as a variant, smooth-MuSIC, which mitigates the effects of multipath interference. Beamforming techniques, which combine temporal and spatial filtering, are also used to find the direction of arrival. These strategies minimize the transmission power needed to send a signal. Further work building on this research can implement directional transmission and receiving with beamforming, which yields many advantages including minimized signal interception. The results from this ...

Attenuation And Photodetection Of Sub-Bandgap Slow Light In Silicon-On-Insulator Photonic Crystal Waveguides, John L. Gelleta

Open Access Dissertations and Theses

A glass-clad, slow-light photonic-crystal waveguide is proposed as a solution to sub-bandgap light detection in silicon photonic circuits. Such detection in silicon is perceived as a challenge owing to silicon's indirect band gap and transparency to 1550nm wavelengths, yet is essential for achieving low-cost, high-yield integration with today's microelectronics industry. Photonic crystals can be engineered in such a way as to enhance light-matter interaction over a specific bandwidth via the reduction of the group velocity of the propagating wave (i.e. the slowing of light). The interaction enhanced for light detection in the present work is electron-hole pair ...

Ultraspectral Data Compression, Rolando Herrero

Electrical Engineering Dissertations

Ultraspectral images capture 2D data tuned at different wavelengths across the mid infrared electromagnetic spectrum. Atmospheric Infrared Sounder (AIRS) remote sensors are ultraspectral sensors that generate images with thousands of highly correlated bands and are considered the future of spectroscopy. The major application of AIRS is the acquisition of atmospheric parameters such as gases, temperature and other quantities to perform climate and weather forecast. Because typical AIRS images are well over 40 MB in size and because they are captured in remote locations data compression (before transmission) becomes a very critical issue. Existent compression studies of AIRS data adapt generic ...

Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi

Electrical and Computer Engineering Faculty Publications

This paper reports on the first demonstration of an ultra-miniaturized, high frequency (215 MHz) and high sensitivity MEMS resonant magnetic field sensor based on an AlN/FeGaB bilayer nano-plate resonator capable of detecting magnetic field at nano-Tesla level. Despite of the reduced volume and the high operating frequency of the sensor, high electromechanical performances were achieved (quality factor Q ≈ 511 and electromechanical coupling coefficient k_t² ≈ 1.63%). This first prototype was characterized for different magnetic field levels from 0 to 152 Oe showing a frequency sensitivity of ~ 1 Hz/nT and a limit of detection of ~ 10 nT.

Self-Calibrated Wireless Sleep Sensing System For Brain Injury Diagnostics, Ali Abedi, Frederick Schwaner, E Mougharbel, M J. Hayes

WiSe-Net Laboratory

A wide range of conditions fall under the category of Mild Traumatic Brain Injury (mTBI) diagnosis. In this article, we focus on a new method during sleep to detect mTBI associated with neuro-cognitive impairment that is not apparent using standard neuro-imaging methods. A wireless pressure sensor system comprising a piezo-resistive flexible substrate paired with a microcontroller and a radio is designed and built to provide information relevant to mTBI detection. The collected information is then processed with a software program to remove noise and interference, and detect both sleep states and cardio-respiratory movements.

Wireless Sensors Without Batteries, Ali Abedi

WiSe-Net Laboratory

No abstract provided.

Energy Harvesting Of Human Kinetic Movement, David Marusiak, Julia Carrillo

Electrical Engineering

Development of kinetic energy scavenging applications from the human body necessitates additional research to assist in designating a mounting position for a potential device. A data acquisition system adequately provides a parametric average power comparison among four locations on the body (waist, upper arm, hand, and calf) for both a male and female subject. Experimentally, the hand-held device provided the highest average power. Thus, subsequent investigation at set speeds provides further analysis of the output’s characteristically linear behavior. The physical energy-harvesting device features a plastic tube casing wrapped with the stationary coiled wire through which a neodymium magnet oscillates ...

Fiber-Tip Fabry-Perot Interferometric Sensor Based On A Thin Silver Film, Fawen Guo

Electrical Engineering Theses and Dissertations

Fiber-optic sensors have many advantages, including small size, light weight, immunity to electromagnetic interference, and the capability of remote sensing. Fiber- tip sensors are fabricated on a fiber tip and are the smallest type of fiber-optic sensor. The fiber-tip sensors have attracted a great deal of attention in past years for pressure, temperature, and acoustic sensing.

In this thesis, a fiber-tip sensor based on an ultra-thin silver film was proposed and demonstrated for highly sensitive and high frequency ultrasonic detection. The film is prepared by the vacuum thermal deposition method and then transferred to the fiber tip. The sensor has ...

Optical Mode Study Of Galium Nitride Based Laser Diodes, Douglas Cattarusa

Electrical Engineering

This paper focuses on the optical mode analysis of laser diodes to improve light emission. Under the mode analysis, we compare the optical confinement factor (OCF) percentage of the emitting light from the LDs. There are two structures which we analyze: a basic GaN waveguide structure and an InGaN waveguide structure. The second structure has additional InGaN waveguides and is analyzed under two additional design variations: the concentration of Indium and the thickness of the top waveguide layer. The results of this study indicate introducing InGaN waveguide layers correlates with lower order modes (zero and first order) and increase the ...

Conductive Concrete For Electromagnetic Shielding – Methods For Development And Evaluation, Aaron P. Krause

Dissertations & Student Research in Computer Electronics & Engineering

This research investigates the development and evaluation innovative methods for the use of conductive concrete as an electromagnetic shield. New testing methods are developed to determine the best conductive components to use in the design of a concrete mixture for shielding that shows the best promise. The conductive concrete mixture has the potential to provide electromagnetic shielding that is cost-effective in terms of construction, operation, and maintenance compared to conventional approaches. Two testing methods, Small Sample Testing and Large Slab Testing, are developed based on standardized testing methods that have been modified for the testing of conductive concrete mixtures. As ...

Chalcogenide Microsphere Fabricated From Fiber Tapers Using Contact With A High-Temperature Ceramic Surface, Pengfei Wang, Ganapathy Murugan, Gilberto Bramilla, Ming Ding, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The fabrication 1 and characterization of a 2 chalcogenide glass microsphere resonator has been demonstrated. 3 At wavelengths near 1550 nm, whispering gallery mode 4 resonances can be efficiently excited in a 74-μm-diameter 5 chalcogenide glass microsphere via evanescent coupling using a 6 tapered silica glass fiber with a waist diameter of circa 2 μm. 7 Resonances with Q-factors greater than 105 were observed. 8 Due to the high nonlinearity properties of the chalcogenide 9 material and the ease of fabrication process, chalcogenide 10 microspheres offer the potential for robustly assembled fully 11 integrated photonic devices. 12 Index Terms—Chalcogenide

Nonlinear Propagation Of Incoherent White Light In A Photopolymerisable Medium: From Single Self-Trapped Beams To 2-D And 3-D Lattices, Kailash Kasala

Open Access Dissertations and Theses

Optical beams that travel through a material without undergoing divergence are known as self-trapped beams. Self-trapping occurs when a beam induces a suitable index gradient in the medium that is capable of guiding the original beam. An incoherent light consists of femtosecond scale speckles, due to random phase fluctuations and were not thought to self-trap until recently. In 1997, Mitchell et al., showed that white light can self-trap, provided the medium cannot respond fast enough to form index gradients to these speckles individually. However, detailed studies have been hampered by a lack of suitable materials and strategies for enabling such ...

Commissioning Of The Asta Laser Lab With Uv Pulse Length Characterization, Daniel Kelley, Jeff Corbett

STEM Teacher and Researcher (STAR) Program Posters

The Linac Coherent Light Source (LCLS) at SLAC depends on a photocathode electron gun to provide the linear accelerator with the raw material – electrons – used for making X-ray laser pulses. The photocathode used in the LCLS Injector is a clean copper plate in high vacuum. When the cathode is struck with high energy UV light, electrons are liberated from its surface and then accelerated down the linac with radio-frequency electric fields. These fast-moving bunches of electrons are directed through an undulator magnet to radiate X-ray light.

Although scientists have been using photocathode techniques at SLAC for 25 years, some important ...

Design Optimization And Modeling Of Plasmonic Structures, Mohamed H. El Sherif

Open Access Dissertations and Theses

In this thesis, we discuss the study and realization of surface plasmon polaritons (SPPs) and their devices. Plasmonics is the emerging field that will help technologies advance further into the nano-scale without the concern for delays or size limitations. SPPs are a more advanced field of photonics as they use metals instead of the semiconductors or insulators used in optics. They operate at frequencies in the light and near infrared spectrum, as this range produces their unique characteristics. Plasmonics possess the miniaturization of electronics and the speed of photonics. They do not suffer from both the delays in nano-electronics, and ...

Complex Mode Calculation By Finite Element Method, Tingxia Li

Open Access Dissertations and Theses

Optical waveguide is a very important component in numerous optical structures, devices and photonic circuits. With the rapid development of fabrication technologies, increasing integrated complexity and different materials characteristics, there is higher demand on high-index contrast waveguide with arbitrary cross section and anisotropic material, which indicates the need to develop an efficient, high-performance mode solver to analyze optical waveguides to reduce the fabrication cycle and total cost. Modeling and simulation methods, including Finite Difference Time-Domain (FDTD) method, Finite Element Method (FEM), Beam Propagating Method (BPM), Mode Matching Method (MMM) and Couple Mode Theory (CMT), etc, have been popular for years ...

Femtosecond Laser Irradiation Of Synthetic Single Crystal Diamond: Studies Of Surface Ripples And Ablation Thresholds, Jasper A. Z. Brawley-Hayes

Open Access Dissertations and Theses

This thesis explores the ablation and texturing of synthetic single crystal diamond under ultrashort laser pulse irradiation in rough vacuum ambient conditions. Experiments were performed with a 1 kHz repetition rate titanium sapphire laser system producing pulses at 800 nm central wavelength and 150 fs pulse duration. First, the production of ordered periodic nanostructures (ripples) on the diamond surface was characterized and the periodicity of these structures was analyzed against irradiation parameters. Ripples were usually found to fall into one of two categories: one with a spatial period near the irradiation wavelength and one with a spatial period near λ ...