Optics Commons^™

High Speed Modulation Characteristics Of Semiconductor Nanolasers And Coupled Ring Laser Systems, Chi Xu

Electronic Theses and Dissertations, 2020-2023

Optical communication systems require light sources that can be modulated with high speeds. However, the modulation bandwidth of laser diodes is typically limited by an intrinsic value, its relaxation resonance frequency. In order to circumvent this limitation, a number of methods have been proposed to boost the modulation speed, including optical injection locking, quantum dots lasers with large differential gain, push-pull modulation in composite lasers. This dissertation explores two new approaches for enhancing the direct modulation bandwidth of semiconductor quantum well laser diodes. Lasers with strong spontaneous emission have been shown to exhibit a high-speed performance theoretically. It is expected …

Therapy And Medical Imaging Applications Of Focusing Polycapillary X-Ray Optics, Weiyuan Sun

Legacy Theses & Dissertations (2009 - 2024)

Focusing polycapillary optics yield high gains in intensity and increased spatial resolution for a variety of clinical, lab-based, synchrotron, or in situ analysis applications. In this dissertation we investigate the extension of two applications of focusing polycapillary optics. The first is the application of polycapillary optics in radiation therapy. This discussion includes measurements and calculation of dose for focused beam orthovoltage therapy. A system has been designed to investigate whether the polycapillary optics can produce an X-ray beam which can give more accurate dose painting due to the higher dose concentration at the focal spot. X-ray exposures were measured with …

Dynamics Of Transmission In Disordered Topological Insulators, Yuhao Kang, Yiming Huang, Azriel Genack

Publications and Research

Robust transmission in topological insulators makes it possible to steer waves without attenuation along bent paths within imperfectly fabricated photonic devices. But the absence of reflection does not guarantee the fidelity of pulsed transmission which is essential for core photonic functionalities. Pulse transmission is disrupted by localized modes in the bulk of topological insulators which coexist with the continuum edge mode and are pushed deeper into the band gap with increasing disorder. Here we show in simulations of the Haldane model that pulse propagation in disordered topological insulators is robust throughout the central portion of the band gap where localized …

Toward Transformable Photonics: Reversible Deforming Soft Cavities, Controlling Their Resonance Split And Directional Emission, Mark Douvidzon, Shai Maayani, Harel Nagar, Tamir Admon, Vladimir Shuvayev, Lan Yang, Lev Deych, Yael Roichman, Tal Carmon

Publications and Research

We report on reversible and continuously deformable soft micro-resonators and the control of their resonance split and directional emission. Assisted by computerized holographic-tweezers, functioning as an optical deformer of our device, we gradually deform the shape and change the functionality of a droplet whispering-gallery cavity. For example, we continuously deform hexagonal cavities to rectangular ones and demonstrate switching to directionally emitting mode-of-operation, or splitting a resonant mode to a 10-GHz separated doublet. A continuous trend of improving spatial light modulators and tweezers suggests that our method is scalable and can control the shape and functionality of many individual devices. We …

Directional Link Management Using In-Band Full-Duplex Free Space Optical Transceivers For Aerial Nodes, A F M Saniul Haq

Electronic Theses and Dissertations, 2020-2023

Free-space optical (FSO) communication has become very popular for wireless applications to complement and, in some cases, replace legacy radio-frequency for advantages like unlicensed band, spatial reuse, and enhanced security. Even though FSO can achieve very high bit-rate (tens of Gbps), range limitation due to high attenuation and weather dependency has always restricted its practical implementation to indoor application like data centers and outdoor application like Project Loon. Building-to-building communication, smart cars, and airborne drones are potential futuristic wireless communication sectors for mobile ad-hoc FSO networking. Increasing social media usage demands high-speed mobile connectivity for applications like video call and …

Ieee Access Special Section Editorial: Trends And Advances In Bio-Inspired Image-Based Deep Learning Methodologies And Applications, Peter Peer, Carlos M. Travieso-Gonzalez, Vijayan K. Asari, Malay Kishore Dutta

Electrical and Computer Engineering Faculty Publications

Many of the technological advances we enjoy today have been inspired by biological systems due to their ease of operation and outstanding efficiency. Designing technological solutions based on biological inspiration has become a cornerstone of research in a variety of areas ranging from control theory and optimization to computer vision, machine learning, and artificial intelligence. Especially in the latter few areas, biologically relevant solutions are becoming increasingly important as we look for new ways to make artificial systems more efficient, intelligent, and overall effective.

A Simple Background Elimination Method For Miniaturized Fiber-Optic Raman Probe, Bohong Zhang

Masters Theses

"Raman scattering is called a photonic - molecular interaction based on the kinetic model of the analytic. Due to the uniqueness of the Raman scattering technique, it can provide a unique fingerprint signal for molecular recognition. However, a serious challenge often encountered in Raman measurement comes from the requirements of fast, real-time remote sensing, background fluorescence suppression, and micro-environmental detection.

A new Miniaturized Fiber-Optic Raman Probe (MFORP) for Raman spectroscopy, used especially for eliminating background fluorescence and enhancing sampling, is presented. Its main purpose is to provide an overview of excellent research on the detection of very small substances and …

A Compact Wavelength Meter Using A Multimode Fiber, Ogbole Collins Inalegwu

Masters Theses

“Wavelength meters are very important for precision measurements of both pulses and continuous-wave optical sources. Conventional wavelength meters employ gratings, prisms, interferometers, and other wavelength-sensitive materials in their design. Here, we report a simple and compact wavelength meter based on a section of multimode fiber and a camera. The concept is to correlate the multimodal interference pattern (i.e., speckle pattern) at the end-face of a multimode fiber with the wavelength of the input lightsource. Through a series of experiments, specklegrams from the end face of a multimode fiber as captured by a charge-coupled device (CCD) camera were recorded; the images …

Asymmetry In Mie Scattering By A Homogeneous Sphere, Samuel Hanna

Honors Program Theses

Azimuthal asymmetry is present in the Mie scattering pattern of light scattered by a homogeneous sphere within a uniform medium. This asymmetry is predicted by Mie theory, which describes such scattering mathematically using solutions to Maxwell's equations. This thesis shows that the asymmetry in Mie scattering patterns is related to the polarization of the light incident on the scatterer. This relationship is reflected in the mathematics of Mie theory. Furthermore, this thesis demonstrates empirically that the polarization of the incident light is related to the asymmetry in Mie scattering patterns. Mie scattering by single polystyrene beads was recorded using an …

Polarization Sensitive Imaging Techniques Using Quantum Entangled Qubits, Vitaly Sukharenko

Dissertations and Theses

The aim of this research is to study imaging techniques using quantum entangled qubits. These techniques extract information about the quantum state of two entangled qubits and corelate the degree of entanglement to each pixel. Imaging information of the underlying structure or material is decoded using the reconstruction of the quantum density matrix along with the calculated entanglement and concurrence levels between the two qubits. Reconstruction of a quantum state and quantum state tomography are of increasing importance in quantum information science. Quantum state tomography is used to describe entanglement of trapped ions [1] and photons [2]. Number of experiments …

Big Data: Potential As An Ocular Epidemiology And Public Health Tool, Michael Moore

Doctoral

Refractive error is a significant cause of vision impairment both through the limited access to correction in some areas and the associated ocular diseases for which refractive errors are risk factors. Having timely, regular access to population level estimates of refractive error and vision impairment is necessary to adequately plan public health resources and resource appropriate interventions. A lack of access to current and regularly updated refractive error and vision impairment prevalence data has been identified as a significant limitation in predicting future population trends with many countries lacking any prevalence data or available data being outdated. This project addresses …

Optically Transparent Microwave Absorber Based On Water-Based Moth-Eye Structures, H Kwon, G D’Aguanno, Andrea Alù

Advanced Science Research Center

We propose an approach to realize an optically transparent microwave absorber based on water-based moth-eye metamaterial structures. The absorber is made of a periodic array of properly shaped glass caps infiltrated with distilled water. Analytical calculations and numerical simulations show that the water-based metamaterial absorbs electromagnetic waves over a wide spectral band ranging from 4GHz to well above 120GHz, showing absorption levels close to 100% for incident radiation that ranges from normal to grazing angles, for both TE and TM polarizations. Yet, the structure is optically transparent, offering exciting opportunities in a variety of civil and military applications, such as …

Fiber Optic Sensors For Industry And Military Applications, Yiyang Zhuang

Doctoral Dissertations

"Fiber optic sensors (FOSs) have been widely used for measuring various physical and chemical measurands owing to their unique advantages over traditional sensors such as small size, high resolution, distributed sensing capabilities, and immunity to electromagnetic interference. This dissertation focuses on the development of robust FOSs with ultrahigh sensitivity and their applications in industry and military areas.

Firstly, novel fiber-optic extrinsic Fabry-Perot interferometer (EFPI) inclinometers for one- and two-dimensional tilt measurements with 20 nrad resolution were demonstrated. Compared to in-line fiber optic inclinometers, an extrinsic sensing motif was used in our prototype inclinometer. The variations in tilt angle of the …

Rapid Quantification Of Biofouling With An Inexpensive, Underwater Camera And Image Analysis, Matthew R. First, Scott C. Riley, Kazi Aminul Islam, Victoria Hill, Jiang Li, Richard C. Zimmerman, Lisa A. Drake

Electrical & Computer Engineering Faculty Publications

To reduce the transport of potentially invasive species on ships' submerged surfaces, rapid-and accurate-estimates of biofouling are needed so shipowners and regulators can effectively assess and manage biofouling. This pilot study developed a model approach for that task. First, photographic images were collected in situ with a submersible, inexpensive pocket camera. These images were used to develop image processing algorithms and train machine learning models to classify images containing natural assemblages of fouling organisms. All of the algorithms and models were implemented in a widely available software package (MATLAB^©). Initially, an unsupervised clustering model was used, and three …

Optical Metasurfaces, Fatih Balli

Theses and Dissertations--Physics and Astronomy

Traditional optical elements, such as refractive lenses, mirrors, phase plates and polarizers have been used for various purposes such as imaging systems, lithographic printing, astronomical observations and display technology. Despite their long-term achievements, they can be bulky and not suitable for miniaturization. On the other hand, recent nanotechnology advances allowed us to manufacture micro and nanoscale devices with ultra-compact sizes. Metasurfaces, 2D engineered artificial interfaces, have emerged as candidates to replace traditional refractive lenses with ultra-thin miniaturized optical elements. They possess sub-wavelength unit cell structures with a specific geometry and material selection. Each unit cell can uniquely tailor the phase, …

Live Cell Biomass Tracking For Basic, Translational, And Clinical Research, Graeme Murray

Theses and Dissertations

Single cell mass is tightly regulated throughout generations and the cell cycle, making it an important marker of cell health. Abnormal changes in cell size can be the first indication of dysfunction in response to environmental stimuli such as cytotoxic drugs. Described here is the further development of high-speed live cell interferometry (HSLCI) to concurrently measure the changes in single cell mass of thousands of cells over time. Critically, the high-throughput nature of HSLCI provides realistic pictures of tumor heterogeneity. This throughput enabled HSLCI to correctly predict in vivo carboplatin sensitivity of three triple negative breast cancer patient derived xenografts, …

Fabrication Of Metal-Silicon Nanostructures By Reactive Laser Ablation In Liquid, Eric J. Broadhead

Theses and Dissertations

Metal-silicon nanostructures are a growing area of research due to their applications in multiple fields such as biosensing and catalysis. In addition, silicon can provide strong support effects to metal nanoparticles while being more cost effective than traditionally used supports, like titania. Traditional wet-chemical methods are capable of synthesizing metal-silicon nanostructures with a variety of composition and nanoparticle shapes, but they often require high temperatures, toxic solvents, strong reducing agents, or need capping agents added to stabilize the nanoparticles. Laser processing is an emerging technique capable of synthesizing metal-silicon composite surfaces that offers a faster, simpler, and greener synthesis route …

Light Field Compression And Manipulation Via Residual Convolutional Neural Network, Eisa Hedayati

Dissertations, Master's Theses and Master's Reports

Light field (LF) imaging has gained significant attention due to its recent success in microscopy, 3-dimensional (3D) displaying and rendering, augmented and virtual reality usage. Postprocessing of LF enables us to extract more information from a scene compared to traditional cameras. However, the use of LF is still a research novelty because of the current limitations in capturing high-resolution LF in all of its four dimensions. While researchers are actively improving methods of capturing high-resolution LF's, using simulation, it is possible to explore a high-quality captured LF's properties. The immediate concerns following the LF capture are its storage and processing …

Understanding The Effects Of Water Vapor And Temperature On Aerosol Using Novel Measurement Methods, Tyler Jacob Capek

Dissertations, Master's Theses and Master's Reports

Aerosol and water are inexorably linked, and both are ubiquitous within our atmosphere and required components for cloud formation. Relative humidity (RH), a temperature dependent quantity, can have a significant influence on the size, shape, and ultimately, the optical properties of the aerosol. RH can vary substantially on small spatial and short temporal scales in turbulent conditions due to rapid fluctuations in temperature and water vapor mixing ratio. Accurate assessment of optical enhancements due to an increase in RH is key for determining the particles’ impact on the climate and visibility.

A humidity-controlled cavity attenuated phase-shift albedometer (H-CAPS-PM_SSA) …

Combined Experimental And Modeling Analysis For Thedevelopment Of Optical Materials Suitable To Enhance Theimplementation Of Plasmonic-Enhanced Luminescent Down-Shifting Solutions On Existing Silicon-Based Photovoltaic Devices, James Walshe, Mihaela Girtan, Sarah Mccormack, John Doran, George Amarandei

Articles

The development of highly efficient solar collectors requires modulating the light interactions with the semiconducting materials. Incorporating luminescent species and metal nanoparticles within a semitransparent polymeric material (e.g., polymethyl methacrylate (PMMA)) leads to the formation of a plasmon-enhanced luminescent down-shifting (PLDS) layer, which offers a retrofittable approach toward expanding the wavelength range over which the conversion process can effectively occur. Adding antireflection coatings (ARCs) further controls the spectral response. However, with each additional component comes additional loss pathways. In this study, the losses related to light interactions with the PMMA and the ARCs have been investigated theoretically using a transfer …

Evaluation Of Postoperative Refractive Error Correction After Cataract Surgery, Ellen Konadu Antwi-Adjei, Emmanuel Owusu, Emmanuel Kobia-Acquah, Emmanuella Esi Dadzie, Emmanuel Anarfi, Seth Wanye

Articles

Suboptimal cataract surgery outcomes remain a challenge in most developing countries. In Ghana, about 2 million people have been reported to be blind due to cataract with about 20% new cases being recorded yearly. The aim of this study was to evaluate postoperative correction of refractive errors after cataract surgery in a selected eye hospital in Ashanti Region, Ghana. This was a retrospective study where medical records of patients (aged 40–100) who reported to an eye hospital in Ghana from 2013–2018 were reviewed. Included in the study were patients aged ≥40 years and patients with complete records. Data on patient …

The Aging And Impacts Of Atmospheric Soot: Closing The Gap Between Experiments And Models, Ogochukwu Yvonne Enekwizu

Dissertations

The main goal of this dissertation is to generate data and parameterizations to accurately represent soot aerosols in atmospheric models. Soot from incomplete combustion of fossil fuels and biomass burning is a major air pollutant and a significant contributor to climate warming. The environmental impacts of soot are strongly dependent on the particle morphology and mixing state, which evolve continuously during atmospheric transport via a process known as aging. To make predictions of soot impacts on the environment, most atmospheric models adopt simplifications of particle structure and mixing state, which lead to substantial uncertainties. Using an experimentally constrained modeling approach, …

Drawing Parallels In Art Science For Collaborative Learning: A Case Study, Karen Westland

The Transdisciplinary STEAM+ Journal

This research paper explores drawing as a tool to facilitate interdisciplinary practice. Outlined is the personal experience of PhD researcher [name removed] in their physics/craft research project, combined with thoughts and opinions from collaborators gathered through group discursive interviews. Interdisciplinary projects face interpersonal and conceptually ambiguous challenges which can be addressed through adopting drawing techniques for educational purposes. Findings highlight that drawing can assist across a breadth of applications as a learning tool for everyone, regardless of drawing ability, to improve the functionality of collaborative projects. Specifically, drawing combined with other communication techniques develops a performative communicative approach that enriches …

Conditional Generative Adversarial Network Demosaicing Strategy For Division Of Focal Plane Polarimeters, Garrett Sargent, Bradley M. Ratliff, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

Division of focal plane (DoFP), or integrated microgrid polarimeters, typically consist of a 2 × 2 mosaic of linear polarization filters overlaid upon a focal plane array sensor and obtain temporally synchronized polarized intensity measurements across a scene, similar in concept to a Bayer color filter array camera. However, the resulting estimated polarimetric images suffer a loss in resolution and can be plagued by aliasing due to the spatially-modulated microgrid measurement strategy. Demosaicing strategies have been proposed that attempt to minimize these effects, but result in some level of residual artifacts. In this work we propose a conditional generative adversarial …

Impact Of The Liquid Crystal Director Twisting On Two-Beam Energy Exchange In A Hybrid Photorefractive Inorganic-Liquid Crystal Cell, Victor Y. Reshetnyak, Igor P. Pinkevych, Michael E. Mcconney, Jonathan E. Slagle, Dean R. Evans

Student Publications

We studied the energy transfer between light beams on the director grating in a hybrid photorefractive liquid crystal (LC) cell assuming the propagation of light waves in the cell to be in the Mauguin regime. This approach makes it possible to trace the change of the gain coefficient dependence on the director grating spacing with the change of the LC director twist. Conditions for the LC flexoelectric parameters and the director helix pitch necessary for transformation the gain coefficient dependence from the nematic to cholesteric type are obtained. The influence of the director splay and bend deformations on the gain …

Parametric Model Development For Heterogeneous Atmospheric Conditions, Daniel Paul Greenway

Electronic Theses and Dissertations

No abstract provided.

Transfer-To-Transfer Learning Approach For Computer Aided Detection Of Covid-19 In Chest Radiographs, Barath Narayanan Narayanan, Russell C. Hardie, Vignesh Krishnaraja, Christina Karam, Venkata Salini Priyamvada Davuluru

Electrical and Computer Engineering Faculty Publications

The coronavirus disease 2019 (COVID-19) global pandemic has severely impacted lives across the globe. Respiratory disorders in COVID-19 patients are caused by lung opacities similar to viral pneumonia. A Computer-Aided Detection (CAD) system for the detection of COVID-19 using chest radiographs would provide a second opinion for radiologists. For this research, we utilize publicly available datasets that have been marked by radiologists into two-classes (COVID-19 and non-COVID-19). We address the class imbalance problem associated with the training dataset by proposing a novel transfer-to-transfer learning approach, where we break a highly imbalanced training dataset into a group of balanced mini-sets and …

Polarization-Selective Modulation Of Supercavity Resonances Originating From Bound States In The Continuum, Chan Kyaw, Riad Yahiaoui, Joshua A. Burrow, Viet Tran, Kyron Keelen, Wesley Sims, Eddie C. Red, Willie S. Rockward, Mikkel A. Thomas, Andrew M. Sarangan, Imad Agha, Thomas A. Searles

Electro-Optics and Photonics Faculty Publications

Bound states in the continuum (BICs) are widely studied for their ability to confine light, produce sharp resonances for sensing applications and serve as avenues for lasing action with topological characteristics. Primarily, the formation of BICs in periodic photonic band gap structures are driven by symmetry incompatibility; structural manipulation or variation of incidence angle from incoming light. In this work, we report two modalities for driving the formation of BICs in terahertz metasurfaces. At normal incidence, we experimentally confirm polarization driven symmetry-protected BICs by the variation of the linear polarization state of light. In addition, we demonstrate through strong coupling …

Explicit Formulas For Solutions Of Maxwell’S Equations In Conducting Media, Valery Yakhno

Applications and Applied Mathematics: An International Journal (AAM)

A new explicit presentation of the fundamental solution of the time-dependent Maxwell’s equations in conducting isotropic media is derived by Hadamard techniques through the fundamental solution of the telegraph operator. This presentation is used to obtain explicit formulas for generalized solutions of the initial value problem for Maxwell’s equations. A new explicit Kirchhoff’s formula for the classical solution of the initial value problem for the Maxwell equations in conducting media is derived. The obtained explicit formulas can be used in the boundary integral method, Green’s functions method and for computation of electric and magnetic fields in conducting media and materials.

Optical Properties Of Ultrathin In(Ga)As/Gaas And In(Ga)N/Gan Quantum Wells, Yurii Maidaniuk

Graduate Theses and Dissertations

Recently, structures based on ultrathin quantum wells (QWs) began to play a critical role in modern devices, such as lasers, solar cells, infrared photodetectors, and light-emitting diodes. However, due to the lack of understanding of the formation mechanism of ultrathin QWs during the capping process, scientists and engineers cannot fully explore the potential of such structures. This study aims to investigate how structural parameters of ultrathin QWs affect their emission properties by conducting a systematic analysis of the optical properties of In(Ga)As/GaAs and In(Ga)N/GaN ultrathin QWs. Specifically, the analysis involved photoluminescence measurements combined with effective bandgap simulation, x-ray diffraction, and …