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Articles 1 - 14 of 14
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1.2-Micron Multi-Section Quantum Dot Superluminescent Diodes, Therese Saiz
1.2-Micron Multi-Section Quantum Dot Superluminescent Diodes, Therese Saiz
Electrical and Computer Engineering ETDs
Superluminescent diodes (SLD) with a center wavelength of 1.2μm are of interest for use in medical imaging of skin tissue especially in the field of optical coherence tomography (OCT). In this thesis a ridge-waveguide multi-section quantum dot SLD that emits at 1.2μm with a bandwidth greater than 100nm and a power greater than 0.2mW is presented. The multi-section SLD allows simultaneous tuning of the ground state emission and excited state emission, resulting in wide bandwidth and high power. Theoretical equations describing the intensity output of the multi-section SLD configuration are presented. It is found that these equations are able to …
Minimally Invasive Capacitive Micromachined Ultrasonic Transducers Array For Biomedical Applications, Xiaoyang Cheng
Minimally Invasive Capacitive Micromachined Ultrasonic Transducers Array For Biomedical Applications, Xiaoyang Cheng
Electrical and Computer Engineering ETDs
Ultrasound covers a broad range of applications from underwater exploration and nondestructive evaluation of materials to medical diagnosis and treatment. The ultrasonic transducer plays an important role in determining the resolution, sensitivity, as well as other critical diagnostic capabilities of an ultrasonic detection or imaging system. Currently piezoelectric ultrasonic transducers dominate the market. The device performance of the piezoelectric ultrasonic transducer in medical applications is limited by the material properties and related electrical and acoustic impedance match issues. The fabrication of piezoelectric transducer array requires meticulous handcrafting. It is difficult and expensive to fabricate densely populated piezoelectric array. The Capacitive …
The Effects Of Non-Uniform Illumination On The Performance Of Series Connected Photovoltaic Arrays, Jason Shelton
The Effects Of Non-Uniform Illumination On The Performance Of Series Connected Photovoltaic Arrays, Jason Shelton
Electrical and Computer Engineering ETDs
Optical power transfer has several advantages that make this technology useful in many applications. Optical power transfer is immune to the noise generating effects of Radio Frequency (RF) and Electromagnetic Interference (EMI). Transferring power optically also has the benefit of generating electricity in regions where electrical isolation is required. Using Series Connected Photovoltaic Arrays (SCPA) for voltage conversion has the advantage in that high voltage can be directly generated in a small volume. These advantages have led to applications in which the optical power is transferred over a fiber optic and converted to electrical power by using an SCPA. Fiber …
Terahertz Photomixing Spectroscopy Of Two-Dimensional Semiconductor Plasmons, Todd Barrick
Terahertz Photomixing Spectroscopy Of Two-Dimensional Semiconductor Plasmons, Todd Barrick
Electrical and Computer Engineering ETDs
This thesis reports the findings of terahertz photomixer spectroscopy performed on plasmonic grating-gate detectors made from high mobility two-dimensional electron gas (2DEG) material. In recent years, these detectors have seen significant improvements in sensitivity and currently exhibit a noise equivalent power of 10^-8 W/sqrt(Hz) However, further improvements are essential for these detectors to become truly useful; the ultimate goal being a NEP < 10^-10 W/sqrt(Hz) To this end, it is necessary to understand the physical properties of the mechanism underlying the detectors photoresponse, namely plasmons. Although two-dimensional plasmons were first observed in semiconductors in 1978, to date, their physical properties, for example scattering and absorption cross section, are relatively unknown. The primary purpose of this work is to develop a measurement system capable of revealing these properties and utilize this system to understand the absorption of radiation by two-dimensional plasmons. By no means will the study of plasmonic properties using this system end when this work is completed. Rather, this work lays the foundation for years of future research in this field.
Inas/Ga(In)Sb Superlattice Based Infrared Detectors Using Nbn Design, Greg Bishop
Inas/Ga(In)Sb Superlattice Based Infrared Detectors Using Nbn Design, Greg Bishop
Electrical and Computer Engineering ETDs
Infrared detectors in the mid-wave infrared (MWIR) (3-5μm) and long-wave infrared (LWIR) (8-12μm) have many applications in military, industrial and medical fields. The state-of-the-art photodetectors based on Hg1-xCdxTe (MCT) have large signal over noise ratio and their bandgap can be tuned to span 1-32 μm wavelength range. However, large tunneling and Auger dark currents due to low electron effective mass in MCT detectors require operation at cryogenic temperatures (77-100 K). The cooling requirement limits the lifetime, adds weight and expense and increases the power consumption of the infrared system. There is a concerted effort to develop photonic detectors operating at …
Bpsk System Analysis Using Mems Filters, David Ho
Bpsk System Analysis Using Mems Filters, David Ho
Electrical and Computer Engineering ETDs
For some military applications, there exists a need for small custom radios. These radios need to be able to survive extreme environments and transmit the necessary data. This can be achieved by using banks of micromechanical filters. These small filters are post-CMOS compatible, allowing hundreds of high-Q filters to be incorporated over a typical RF transceiver die. Selection of these filters allows the band, channel, and bandwidth to be rapidly changed in operation. Having integrated Microelectromechanical Systems (MEMS) filters eliminates the need for off-chip components such as crystal references and Surface Acoustic Wave (SAW) filters. This allows for smaller, low …
Semiconductor Yield Analysis And Prediction Using A Stochastic Layout Sensitivity Model, Rani S. Ghaida
Semiconductor Yield Analysis And Prediction Using A Stochastic Layout Sensitivity Model, Rani S. Ghaida
Electrical and Computer Engineering ETDs
Spot defects represent the main challenge for enhancement of semiconductor manufacturing yield. As a result, the yield of modern integrated circuits is associated with the layout sensitivity to defects. The term layout sensitivity' is defined as the ratio of 'critical area', i.e. part of the layout in which a defect must be placed to cause a functional failure of the device, to the overall layout area. Semiconductor yield models are traditionally based on the analysis of the 'critical area'. Such models give accurate results; however, critical area analysis requires massive computations that render these models effort and time consuming. The …
The Inverse Kinetics Method And Pid Compensation Of The Annular Core Research Reactor, Benjamin Garnas
The Inverse Kinetics Method And Pid Compensation Of The Annular Core Research Reactor, Benjamin Garnas
Electrical and Computer Engineering ETDs
This thesis explores the development of a model describing the Annular Core Research Reactor (ACRR), the application of the inverse kinetics method to calculate the current reactivity level within the ACRR model, and the development of a PID compensator to automatically control the reactivity level within the model and thus controlling the power level.
Quantum Dot Gain-Lever Laser Diode, Nader Naderi
Quantum Dot Gain-Lever Laser Diode, Nader Naderi
Electrical and Computer Engineering ETDs
Semiconductor quantum dot (QD) lasers are competitive candidates for many applications such as high-speed long-haul optical communication systems. This is due to their superior lasing characteristics (compared to conventional quantum well (QW) lasers) and also their potential for high differential gain and direct modulation with negligible chirp. Recently, substantial efforts have been made to improve the modulation characteristics of QD semiconductor lasers such as enhancing the modulation efficiency and improving the overall modulation bandwidth. The gain lever effect is a method used to enhance the efficiency of amplitude modulation and optical frequency modulation at microwave frequencies by taking advantage of …
Advanced Parallel Magnetic Resonance Imaging Methods With Applications To Mr Spectroscopic Imaging, Ricardo Otazo
Advanced Parallel Magnetic Resonance Imaging Methods With Applications To Mr Spectroscopic Imaging, Ricardo Otazo
Electrical and Computer Engineering ETDs
Parallel magnetic resonance imaging offers a framework for acceleration of conventional MRI encoding using an array of receiver coils with spatially-varying sensitivities. Novel encoding and reconstruction techniques for parallel MRI are investigated in this dissertation. The main goal is to improve the actual reconstruction methods and to develop new approaches for massively parallel MRI systems that take advantage of the higher information content provided by the large number of small receivers. A generalized forward model and inverse reconstruction with regularization for parallel MRI with arbitrary k-space sub-sampling is developed. Regularization methods using the singular value decomposition of the encoding matrix …
Modeling The Effects Of Proton Irradiation [On] Cigs Solar Cells, Jacob Dunken
Modeling The Effects Of Proton Irradiation [On] Cigs Solar Cells, Jacob Dunken
Electrical and Computer Engineering ETDs
The space environment is very harsh on photovoltaic devices. Solar protons (hydrogen ions) cause large numbers of vacancies, which act as recombination centers at deep levels and can create compensating defects that reduce the acceptor concentration at shallow levels in semiconductors. This in turn, can reduce the output power generated by photovoltaic devices. Damage can also occur from atomic oxygen, plasma discharges and electron irradiation. Solar arrays have to be manufactured to produce more power than necessary so that the solar array will still produce the needed amount of power after degradation occurring from charged particle irradiation. A major challenge …
Characterization Of Spectral Response Of A Quantum Dots-In-A-Well Infrared Focal Plane Array, Michael Lenz Ii
Characterization Of Spectral Response Of A Quantum Dots-In-A-Well Infrared Focal Plane Array, Michael Lenz Ii
Electrical and Computer Engineering ETDs
Spectral characterization of a novel single bump, two-color InAs/InGaAs quantum dots-in-a-well (DWELL) infrared focal plane array (FPA) was undertaken and reported here. The hypothesis of the study is that the FPA will exhibit bias-tunable spectral response. Broadband and two-color performance measures of the DWELL FPA are discussed and presented. The DWELL structure is a hybrid of a quantum dot (QD) photodetector consisting of an active region composed of InAs quantum dots embedded in InGaAs quantum wells. The DWELL FPA demonstrates mid-wave infrared (MWIR) and long-wave infrared (LWIR) performance believed to be attributed to transitions from bound states in the dot …
Analysis And Design Of Reconfigurable Multi-Band Stacked Microstrip Patch Antennas (Msas) For Wireless Applications, Mahmoud Alayesh
Analysis And Design Of Reconfigurable Multi-Band Stacked Microstrip Patch Antennas (Msas) For Wireless Applications, Mahmoud Alayesh
Electrical and Computer Engineering ETDs
There is an increasing demand for smaller low-cost reconfigurable antennas that can be easily integrated with packaging structures. Reconfigurable Microstrip Patch Antennas (MSAs) received great attention in wireless communication systems due to their capability to vary their operating frequency, pattern and polarization. Reconfigurability enables us to accommodate more than one service using the same antenna. This thesis presents the analysis and design of new reconfigurable stacked (MSAs) of operating frequencies in the range of (2-5) GHz. The first new antenna is composed of two layers. The bottom layer is a MSA with two slots designed on each side that can …
Injection Locking Characteristics Of Indium Arsenide Quantum Dash Lasers, Aaron Moscho
Injection Locking Characteristics Of Indium Arsenide Quantum Dash Lasers, Aaron Moscho
Electrical and Computer Engineering ETDs
The study of injection locking characteristics was performed on an InAs Quantum Dash (QDash) semiconductor laser for the first time. The linewidth enhancement factor(α-parameter) of a QDash laser was measured using an injection locking technique that takes advantage of the asymmetry of the injection range. Studies were performed as functions of injecesed photon density, wavelength, and output power. To understand the behavior of the α-parameter versus wavelength, the Hakki-Paoli method, a technique that utilized the below threshold amplified spontaneous emission spectrum, was used to measure the modal gain over 1550 nm to 1573 nm. The α-parameter was found to have …