Faraday-Talbot Effect From A Circular Array Of Pillars,
2017
California Polytechnic State University, San Luis Obispo
Faraday-Talbot Effect From A Circular Array Of Pillars, Jessica J. Pilgram
Physics
When an oil bath is vertically oscillating with an acceleration above some critical value, known as the Faraday threshold, the bath surface becomes unstable and nonlinear standing wave patterns emerge. One phenomenon that has been observed above the Faraday threshold is the formation of Faraday-Talbot carpets, resulting from near-field diffraction. The optical Talbot effect occurs when a monochromatic wave passes through a diffraction grating. In the near-field, the formation of self- images is observed at integer multiples of what is known as the Talbot length. These two-dimensional patterns have various applications including X-ray imaging and atom and particle trapping. Two- …
Identifying Sources Of Low-Spatial Frequency Figure Errors In Full-Shell X-Ray Optics,
2017
University of Alabama in Huntsville
Identifying Sources Of Low-Spatial Frequency Figure Errors In Full-Shell X-Ray Optics, Samantha Johnson, Wayne Baumgartner
Von Braun Symposium Student Posters
No abstract provided.
Fabrication And Characterization Of Thermo-Optic Mach-Zehnder Silicon Modulator,
2017
Rose-Hulman Institute of Technology
Fabrication And Characterization Of Thermo-Optic Mach-Zehnder Silicon Modulator, Yeongho Park
Graduate Theses - Physics and Optical Engineering
This thesis focuses on the modeling, design, and fabrication of the Thermo-Optic Mach-Zehnder Modulator, which is one of the simple active devices in silicon photonics. The Mach-Zehnder interferometer (MZI) was formed as an optical path on a silicon on insulator (SOI) wafer of 2040±80 nm thick, and the thermo-optic effect was used to modulate the infrared light of 1553 nm wavelength by controlling the temperature of the one arm of the MZI. To fabricate and understand the Si photonic device, the whole process from theory to the measurement setup is introduced. Additionally, all the fabrication details and some informative experiments …
Confocal Laser Induced Fluorescence With Comparable Spatial Localization To The Conventional Method,
2017
West Virginia University
Confocal Laser Induced Fluorescence With Comparable Spatial Localization To The Conventional Method, Derek S. Thompson, Miguel F. Henriquez, Earl E. Scime, Timothy N. Good
Physics and Astronomy Faculty Publications
We present measurements of ion velocity distributions obtained by laser induced fluorescence (LIF) using a single viewport in an argon plasma. A patent pending design, which we refer to as the confocal fluorescence telescope, combines large objective lenses with a large central obscuration and a spatial filter to achieve high spatial localization along the laser injection direction. Models of the injection and collection optics of the two assemblies are used to provide a theoretical estimate of the spatial localization of the confocal arrangement, which is taken to be the full width at half maximum of the spatial optical response. The …
Use Of A Novel Infrared Wavelength-Tunable Laser Mueller-Matrix Polarimetric Scatterometer To Measure Nanostructured Optical Materials,
2017
Air Force Institute of Technology
Use Of A Novel Infrared Wavelength-Tunable Laser Mueller-Matrix Polarimetric Scatterometer To Measure Nanostructured Optical Materials, Jason C. Vap, Stephen E. Nauyoks, Michael R. Benson, Michael A. Marciniak
Faculty Publications
Nanostructured optical materials, for example, metamaterials, have unique spectral, directional, and polarimetric properties. Samples designed and fabricated for infrared (IR) wavelengths have been characterized using broadband instruments to measure specular polarimetric transmittance or reflectance as in ellipsometry or integrated hemisphere transmittance or reflectance. We have developed a wavelength-tunable IR Mueller-matrix (Mm) polarimetric scatterometer which uses tunable external-cavity quantum-cascade lasers (EC-QCLs) to tune onto and off of the narrowband spectral resonances of nanostructured optical materials and performed full polarimeteric and directional evaluation to more fully characterize their behavior. Using a series of EC-QCLs, the instrument is tunable over 4.37-6.54 μm wavelengths …
Laser Heating Of Graphite And Pulsed Laser Ablation Of Titanium And Aluminum,
2017
Air Force Institute of Technology
Laser Heating Of Graphite And Pulsed Laser Ablation Of Titanium And Aluminum, William A. Bauer
Theses and Dissertations
Tactical missions for laser weapons include a wide variety of targets, increasing the demands on the laser lethality community. New approaches to reducing the dimensionality of laser and materials interactions are necessary to increase predictive capability. Self-contained systematic experimental study was conducted on continuous wave and pulsed laser interaction with graphite, Al, and Ti. The spectroscopy and plume dynamics from the heating and ablation of these materials was examined to characterize laser weapons effects, develop graphite response for thermal protection systems, and provide optical diagnostics for materials processing. Furthermore, analysis of ablated plume velocity distributions shows application of conventional Maxwell-Boltzmann …
Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers,
2017
Michigan Technological University
Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers, M. H. Teimourpour, M. Khajavikhan, Demetrios N. Christodoulides, Ramy El-Ganainy
Department of Physics Publications
We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain …
Synthesis Of Non-Uniformly Correlated Partially Coherent Sources Using A Deformable Mirror,
2017
Air Force Institute of Technology
Synthesis Of Non-Uniformly Correlated Partially Coherent Sources Using A Deformable Mirror, Milo W. Hyde Iv, Santasri Bose-Pillai, Ryan A. Wood
Faculty Publications
The near real-time synthesis of a non-uniformly correlated partially coherent source using a low-actuator-count deformable mirror is demonstrated. The statistical optics theory underpinning the synthesis method is reviewed. The experimental results of a non-uniformly correlated source are presented and compared to theoretical predictions. A discussion on how deformable mirror characteristics such as actuator count and pitch affect source generation is also included.
Control Of Light-Matter Interaction In 2d Semiconductors,
2017
CUNY Graduate Center
Control Of Light-Matter Interaction In 2d Semiconductors, Zheng Sun
Dissertations, Theses, and Capstone Projects
In this thesis we discuss the control of light matter interaction in low dimensional nanostructure cavity light confining structures. These structures have controllable dispersion properties through design which can be exploited to modify the interaction of light and matter. We will discuss two different types of light confining microcavities: a dielectric cavity and a metal cavity. The specific design of the cavity gives rise to the confinement of the electric field in the center where the nano-materials are placed. In this work, the main material was on the new class of two- dimensional semiconductors of transition metal dichalcogenides (TMDs). Due …
Nonlinear Optical Studies Of Defects And Domain Structures In Perovskite-Type Dielectric Ceramics,
2017
CUNY Graduate Center
Nonlinear Optical Studies Of Defects And Domain Structures In Perovskite-Type Dielectric Ceramics, David J. Ascienzo
Dissertations, Theses, and Capstone Projects
In order to improve future generations of dielectric capacitors a deeper understanding of voltage-induced dielectric breakdown and electrical energy storage limitations is required. This dissertation presents the use of far-field optical second harmonic generation (SHG) polarimetry for probing structural defects and polar domains in linear and nonlinear perovskite dielectric ceramics. We investigated the formation of electric field-induced structural distortions at pristine Fe-doped SrTiO3 (Fe:STO) electrode interfaces, structural defect and strain formation due to oxygen vacancy migration in electrodegraded Fe:STO single crystals, and mixed tetragonal and rhombohedral phase domains in ferroelectric Zr-doped BaTiO3 (BZT) films exhibiting excellent …
Eikonal+ Training And Simulation Platform: Enabling A New Generation Of Optical Systems,
2017
Florida Institute of Technology
Eikonal+ Training And Simulation Platform: Enabling A New Generation Of Optical Systems, Daniel K. Nikolov
Link Foundation Modeling, Simulation and Training Fellowship Reports
The year of 2016 was proclaimed by many to be the year of virtual/augmented reality [Forbes]. The public attention was captured by the idea of wearable and immersive devices that can be used for communication, training, simulation and much more. However, the realization of such AR/VR displays has been staggered due to limitation of the optical/light engine of those devices. Furthermore, head-worn displays are only one example of a new generation of optical systems that require non-traditional technologies to achieve high optical performance, in a compact and light form factor. The development of these technologies requires a new set of …
Fresnel Spatial Filtering Of Quasihomogeneous Sources For Wave Optics Simulations,
2017
Air Force Institute of Technology
Fresnel Spatial Filtering Of Quasihomogeneous Sources For Wave Optics Simulations, Milo W. Hyde Iv, Santasri Bose-Pillai
Faculty Publications
High-spatial-frequency optical fields or sources are often encountered when simulating directed energy, active imaging, or remote sensing systems and scenarios. These spatially broadband fields are a challenge in wave optics simulations because the sampling required to represent and then propagate these fields without aliasing is often impractical. To address this, two spatial filtering techniques are presented. The first, called Fresnel spatial filtering, finds a spatially band-limited source that, after propagation, produces the exact observation plane field as the broadband source over a user-specified region of interest. The second, called statistical or quasihomogeneous spatial filtering, finds a spatially band-limited source that, …
Construction And Passive Q-Switching Of A Ring-Cavity Erbium-Doped Fiber Laser Using Carbon Nanotubes As A Saturable Absorber, Austin Scott
Graduate Theses - Physics and Optical Engineering
The purpose of this thesis is to design, build, test, and achieve pulsed operation of a ring-cavity erbium-doped fiber laser using carbon nanotubes as a saturable absorber. The erbium-doped fiber is characterized first, cross-sections are calculated, and the gain value is determined. Subsequently, the ring cavity is constructed and the laser is operated in the continuous wave regime. Much time is then spent trying to characterize and utilize the carbon nanotubes successfully. Many dispersions are made using multiple solvents and dispersing media, various images are taken with both scanning electron and Raman microscopy, and attempts at purification are made. Saturable …
Raman Spectroscopy Of Oxygen Evolution Catalysts And Psii Manganese Model Compounds,
2017
Purdue University
Raman Spectroscopy Of Oxygen Evolution Catalysts And Psii Manganese Model Compounds, Sergei Shmakov, Daniel A. Hartzler, Alireza Karbakhsh Ravari, Yulia Pushkar
The Summer Undergraduate Research Fellowship (SURF) Symposium
Photosynthesis is the basis of life on earth, and oxygen evolution catalysts are key components of this complicated, yet not fully understood process. Photosystem II, a large membrane bound pigment-protein complex, is the key system that facilitates oxygenic photosynthesis via the oxygen evolving complex (a natural oxygen evolving catalyst). It is a key component in oxygen producing catalysts, which can be used in fields such as energy production and biomimetic catalysts. The oxygen evolution cycle, or Kok cycle going within it is still not studied completely. In this project, we were studying the vibrational (and structural) state of a Manganese …
On-Chip Training Of Memristor Crossbar Based Multi-Layer Neural Networks,
2017
University of Dayton
On-Chip Training Of Memristor Crossbar Based Multi-Layer Neural Networks, Raqibul Hasan, Tarek M. Taha, Christopher Yakopcic
Electrical and Computer Engineering Faculty Publications
Memristor crossbar arrays carry out multiply-add operations in parallel in the analog domain, and so can enable neuromorphic systems with high throughput at low energy and area consumption. On-chip training of these systems have the significant advantage of being able to get around device variability and faults. This paper presents on-chip training circuits for multi-layer neural networks implemented using a single crossbar per layer and two memristors per synapse. Using two memristors per synapse provides double the synaptic weight precision when compared to a design that uses only one memristor per synapse. Proposed on-chip training system utilizes the back propagation …
Estimating Index Of Refraction For Specular Reflectors Using Passive Polarimetric Hyperspectral Radiance Measurements,
2017
Air Force Research Laboratory
Estimating Index Of Refraction For Specular Reflectors Using Passive Polarimetric Hyperspectral Radiance Measurements, Jacob A. Martin, Kevin C. Gross
Faculty Publications
Results of a method of estimating index of refraction from passive, polarimetric hyperspectral imaging radiance measurements are presented. As off-nadir viewing hyperspectral imaging platforms gain prominence, estimating index of refraction, which is invariant to viewing angle, may prove advantageous to estimating the emissivity, which is not. Results show that index of refraction can be retrieved to within 8% rms error for fused silica and sapphire glass targets, while simultaneously estimating object temperature. The accuracy and self-consistency of this technique for estimating index of refraction are shown to compare favorably to the maximum smoothness temperature–emissivity separation algorithm. Additionally, the results show …
Nanoscale Tilt Measurement Using A Cyclic Interferometer With Phase Stepping And Multiple Reflections,
2017
Rose-Hulman Institute of Technology
Nanoscale Tilt Measurement Using A Cyclic Interferometer With Phase Stepping And Multiple Reflections, Tahereh Naderishahab
Graduate Theses - Physics and Optical Engineering
High accuracy tilt or roll angle measurement is required for a variety of engineering and scientific applications. Optical interferometry is normally used because it is non-contact and can measure tilt with a very high degree of accuracy. In this thesis, a cyclic interferometer has been developed with four mirrors to measure tilt angles as small as a few nanoradians. To measure the phase, a novel and simple method of phase shift by polarization was developed to enhance measurement sensitivity and accuracy. Since the cyclic interferometer is insensitive to external vibrations and turbulences, polarization phase step was accomplished with relative ease. …
Optimizing An Electron's Path To Ionization Using A Genetic Algorithm,
2017
Ursinus College
Optimizing An Electron's Path To Ionization Using A Genetic Algorithm, Jason Bennett, Kevin Choice
Physics and Astronomy Summer Fellows
A Rydberg atom is an atom with a highly excited and weakly bound valence electron. A widespread method of studying quantum mechanics with Rydberg atoms is to ionize the electron and measure its arrival time. We use a Genetic Algorithm (GA) to control the electron's path to ionization. The Rydberg electron's energy levels are strongly shifted by the presence of an electric field. The energy levels shift and curve, but never cross. At an avoided crossing the electron can jump from one level to the next. By engineering the electric field's time dependence, we thereby control the path to ionization. …
Real-Time Camera Tracking System Using Optical Flow Feature Points,
2017
Air Force Institute of Technology
Real-Time Camera Tracking System Using Optical Flow Feature Points, Daniel D. Doyle, Alan L. Jennings, Jonathan T. Black
AFIT Patents
A new apparatus and method for tracking a moving object with a moving camera provides a real-time, narrow field-of-view, high resolution and on target image by combining commanded motion with an optical flow algorithm for deriving motion and classifying background. Commanded motion means that movement of the pan, tilt and zoom (PTZ) unit is “commanded” by a computer, instead of being observed by the camera, so that the pan, tilt and zoom parameters are known, as opposed to having to be determined, significantly reducing the computational requirements for tracking a moving object. The present invention provides a single camera pan …
High Precision Refractive Index Measurement Techniques Applied To The Analysis Of Neutron Damage And Effects In Caf2 Crystals,
2017
University of New Mexico
High Precision Refractive Index Measurement Techniques Applied To The Analysis Of Neutron Damage And Effects In Caf2 Crystals, Joseph P. Morris Ph.D.
Nuclear Engineering ETDs
Neutron irradiation damages material by atomic displacements. The majority of these damage regions are microscopic and difficult to study, though they can cause a change in density and thus a change in refractive index in transparent materials. This work utilized CaF2 crystals to track refractive index change based on neutron radiation dose. High precision refractive index measurements were performed utilizing a nested-cavity mode-locked laser where the CaF2 crystal acted as a Fabry-Pérot Etalon (FPE). By comparing the repetition rate of the cavity and the repetition rate of the FPE, refractive index change was determined. Following several irradiation experiments, …
