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Full-Text Articles in Physical Sciences and Mathematics
Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell
Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell
Electronic Theses and Dissertations
Photoelectrochemical water splitting has been identified as a promising route for achieving sustainable energy future. However, semiconductor materials with the appropriate optical, electrical and electrochemical properties have yet to be discovered. In search of an appropriate semiconductor to fill this gap, GaSbP, a semiconductor never tested for PEC performance is proposed here and investigated. Density functional theory (DFT+U) techniques were utilized to predict band gap and band edge energetics for GaSbP alloys with low amount of antimony. The overall objective of this dissertation is to understand the suitability of GaSbxP1-x alloys for photoelectrochemical water splitting application. Specifically, …
Electrical Parasitic Bandwidth Limitations Of Oxide-Free Lithographic Vertical-Cavity Surface-Emitting Lasers, Xu Yang
Electronic Theses and Dissertations
Nowadays, Vertical-Cavity Surface-Emitting Lasers (VCSELs) are the most popular optical sources in short-reach data communications. In the commercial oxide VCSEL technology, an oxide aperture is created inside resonant cavity in realizing good mode and current confinement, however, high electrical resistance comes along with forming the oxide aperture and the electrical parasitic bandwidth becomes the main limitation in modulation speed. In this report, electrical bandwidths of oxide-free lithographic VCSELs have been studied along with their general lasing properties. Due to the new ways of fabricating the aperture, record low resistances have been achieved in oxide-free lithographic VCSELs with various sizes, while …
Broad Bandwidth Optical Frequency Combs From Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers, Anthony Klee
Broad Bandwidth Optical Frequency Combs From Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers, Anthony Klee
Electronic Theses and Dissertations
Mode-locked lasers have numerous applications in the areas of communications, spectroscopy, and frequency metrology. Harmonically mode-locked semiconductor lasers with external ring cavities offer a unique combination of benefits in that they can produce high repetition rate pulse trains with low timing jitter, achieve narrow axial mode linewidths, have the potential for entire monolithic integration on-chip, feature high wall-plug efficiency due to direct electrical pumping, and can be engineered to operate in different wavelength bands of interest. However, lasers based on InP/InGaAsP quantum well devices which operate in the important telecom C-band have thus far been relatively limited in bandwidth as …
Multi-Purpose Device For Analyzing And Measuring Ultra-Short Pulses, Naman Anilkumar Mehta
Multi-Purpose Device For Analyzing And Measuring Ultra-Short Pulses, Naman Anilkumar Mehta
Electronic Theses and Dissertations
Intensity auto correlator is device to measure pulse widths of ultrashort pulses on the order of picoseconds and femtoseconds. I have built an in-house, compact, portable, industry standard intensity auto correlator for measuring ultrashort pulse-widths. My device is suitable for pulse-widths from 500 ps to 50 fs. The impetus for developing this instrument stemmed from our development of a multicore-fiber laser for high power laser applications, which also produces very short pulses that cannot be measured with an oscilloscope. As techniques for measuring short pulse-widths have been well studied, what made my journey exciting was the process of taking an …
Product Authentication Using Hash Chains And Printed Qr Codes, Harshith R. Keni
Product Authentication Using Hash Chains And Printed Qr Codes, Harshith R. Keni
Electronic Theses and Dissertations
This thesis explores the usage of simple printed tags for authenticating products. Printed tags are a cheap alternative to RFID and other tag based systems and do not require specialized equipment. Due to the simplistic nature of such printed codes, many security issues like tag impersonation, server impersonation, reader impersonation, replay attacks and denial of service present in RFID based solutions need to be handled differently. An algorithm that utilizes hash chains to secure such simple tags while still keeping cost low is discussed. The security characteristics of this scheme as well as other product authentication schemes that use RFID …
Breast Cancer Classification Of Mammographic Masses Using Circularity Max Metric, A New Method, Tae Keun Heo
Breast Cancer Classification Of Mammographic Masses Using Circularity Max Metric, A New Method, Tae Keun Heo
Electronic Theses and Dissertations
Breast cancer classification can be divided into two categories. The first category is a benign tumor, and the other is a malignant tumor. The main purpose of breast cancer classification is to classify abnormalities into benign or malignant classes and thus help physicians with further analysis by minimizing potential errors that can be made by fatigued or inexperienced physicians. This paper proposes a new shape metric based on the area ratio of a circle to classify mammographic images into benign and malignant class. Support Vector Machine is used as a machine learning tool for training and classification purposes. The improved …
Advanced Blue Phase Liquid Crystal Displays, Daming Xu
Advanced Blue Phase Liquid Crystal Displays, Daming Xu
Electronic Theses and Dissertations
Thin-film transistor (TFT) liquid crystal displays (LCDs) have become indispensable in our daily lives. Their widespread applications range from smartphones, laptops, TVs to navigational devices, data projectors and wearable displays. Over past decades, massive efforts have been invested in device development, material characterization and manufacturing technology. As a result, the performance of LCDs, such as viewing angle, contrast ratio, color gamut and resolution, have been improved significantly. Nonetheless, there are still urgent needs for fast response time and low power consumption. Fast response time helps reduce motion image blurs and enable color sequential displays. The latter is particularly attractive since …
Sensing Using Specialty Optical Fibers, Amy Van Newkirk
Sensing Using Specialty Optical Fibers, Amy Van Newkirk
Electronic Theses and Dissertations
Fiber optic based sensing is a growing field with many applications in civil and aerospace engineering, oil and gas industries, and particularly in harsh environments where electronics are not able to function. Optical fibers can be easily integrated into structures, are immune to electromagnetic interference, can be interrogated from remote distances, and can be multiplexed for distributed measurements. Because of these properties, specialty fiber designs and devices are being explored for sensing temperature, strain, pressure, curvature, refractive index, and more. Here we show a detailed analysis of a multicore fiber (MCF) for sensing, including its design and optimization in simulation, …
Intrinsic Modulation Response Modeling And Analysis For Lithographic Vertical-Cavity Surface-Emitting Lasers, Mingxin Li
Intrinsic Modulation Response Modeling And Analysis For Lithographic Vertical-Cavity Surface-Emitting Lasers, Mingxin Li
Electronic Theses and Dissertations
Vertical-cavity surface-emitting lasers (VCSELs) have been greatly improved and successfully commercialized over the past few decades owing to their ability to provide both mode and current confinement that enables low energy consumption, high efficiency and high modulation speed. However, further improvement of oxide VCSELs is limited by the nature of the oxide aperture because of self-heating, internal strain and difficulties in precise size control. In this dissertation, VCSELs using lithographic approach are demonstrated to overcome the limitations of oxide VCSELs, in which an intra-cavity phase shifting mesa is applied to define the device size and provide optical mode and electrical …
Implementation Of An Air Supply Unit Control Scheme For The Uc2av (Unmanned Circulation Control Aerial Vehicle), Cameron Rosen
Implementation Of An Air Supply Unit Control Scheme For The Uc2av (Unmanned Circulation Control Aerial Vehicle), Cameron Rosen
Electronic Theses and Dissertations
The expanded prevalence of Unmanned Aerial Vehicles (UAVs) in recent years has created many opportunities to research novel applications for their use, enabled by the reduced cost, mission flexibility, and reduced risk that small-scale unmanned platforms provide in comparison to larger aircraft. Despite the versatility of unmanned aviation, limitations on payload size and weight, fuel and power capacity, and takeoff and landing infrastructure can restrict UAV applications, and have created a need for lift augmenting technologies that can reduce the impact of these limitations. Circulation Control (CC) is an active flow technique that has been proven as a method for …