Physics Commons^™

Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena

Physics & Astronomy ETDs

Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …

A Rotating Aperture Mask For Small Telescopes, Edward L. Foley

Master's Theses

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that …

Measuring Length Of Electron Bunches With Optics In Lcls-Ii, Nathan Ahn, Alan Fisher

STAR Program Research Presentations

Since the launch of the LINAC Coherent Light Source (LCLS) in 2009, there have been over 1,000 publications enabling pioneering research across multiple fields. Advances include: harnessing the sun’s light, revealing life’s secrets and aiding drug development, developing future electronics, designing new materials and exploring fusion, customizing chemical reactions, and many more. These discoveries gathered worldwide attention, and now work has begun on a new revolutionary tool, LCLS-II. The LCLS-II will pulse at a million times a second, compared to the 120 pulses from the LCLS. Within the LCLS-II, there are two chicanes, serpentine curves. As the electron beam passes …

Studying Near-Critical And Super-Critical Fluids In Reduced Gravity, Christian Hawkins, Ana Oprisan, Carole Lecoutre-Chabot, Yves Garrabos, Daniel Beysens

Journal of the South Carolina Academy of Science

Critical and supercritical fluids have a variety of applications, from use as machine lubricants in high pressure or high temperature environments to the manufacturing of materials such as aerogel. The optical properties of fluids undergo rapid changes near the critical point resulting in a rapid increase in turbidity known as critical opalescence. These optical changes can be used to probe the universality of critical behavior. As a fluid approaches the critical point, the compressibility rapidly increases. In a gravitational field, this increase in compressibility leads to near-critical fluids stratifying by phase and density, making it difficult to observe the optical …

Tailored Frequency Comb Structures And Their Sensing Applications, James Hendrie

Optical Science and Engineering ETDs

The focus of this dissertation is the development and investigation of nested cavity mode-locked lasers and their resultant tailored frequency combs. A nested cavity is made up of two cavities, known as parents. One parent is a larger, active, 100MHz Ti:Saph oscillator and the other is a smaller, passive, 7GHz Fabry-Perot Etalon (FPE). Unlike standard frequency combs that are continuous, a tailored comb’s teeth are distributed in equally spaced groups where the center of each group corresponds to the resonance of the FPE and the side bands are determined by the resonances of the Ti:Saph. This unique coupling of the …

Monolayer Doping Of Silicon-Germanium Alloys: A Balancing Act Between Phosphorus Incorporation And Strain Relaxation, Noel Kennedy, Ray Duffy, Gioele Mirabelli, Luke Eaton, Nikolay Petkov, Justin D. Holmes, Chris Hatem, Lee Walsh, Brenda Long

Cappa Publications

This paper presents the application of monolayer doping (MLD) to silicon-germanium (SiGe). This study was carried out for phosphorus dopants on wafers of epitaxially grown thin films of strained SiGe on silicon with varying concentrations of Ge (18%, 30%, and 60%). The challenge presented here is achieving dopant incorporation while minimizing strain relaxation. The impact of high temperature annealing on the formation of defects due to strain relaxation of these layers was qualitatively monitored by cross-sectional transmission electron microscopy and atomic force microscopy prior to choosing an anneal temperature for the MLD drive-in. Though the bulk SiGe wafers provided are …

Slow Light With Interleaved P-N Junction To Enhance Performance Of Integrated Mach-Zehnder Silicon Modulators, Marco Passoni, Dario Gerace, Liam O'Faolain, Lucio Claudio Andreani

Cappa Publications

Slow light is a very important concept in nanophotonics, especially in the context of photonic crystals. In this work, we apply our previous design of band-edge slow light in silicon waveguide gratings [M. Passoni et al, Opt. Express 26, 8470 (2018)] to Mach-Zehnder modulators based on the plasma dispersion effect. The key idea is to employ an interleaved p-n junction with the same periodicity as the grating, in order to achieve optimal matching between the electromagnetic field profile and the depletion regions of the p-n junction. The resulting modulation efficiency is strongly improved as compared to common modulators based on …

Generation And Use Of Femtosecond, Gigawatt, Near Infrared Laser Pulses From An Amplified, Mode-Locked, Ti:Sapphire Laser, David Anthony Valdés

Optical Science and Engineering ETDs

This work modeled the early to middle successes achieved in the field of ultrafast, high peak power optics, beginning with the work of Nobel Prize winners Donna Strickland and Gérard Mourou in 1985. In our work, 100 fs light pulses of around 800 nm were generated by a Ti:Sapphire oscillator, then amplified to approximately 30 GW peak power using a chirped pulse amplification system that included regenerative and multi-pass amplifiers. As a verification of our pulses having high peak powers and ultrashort durations, they were then used to strike water, glass, and a Kerr Cell. Supercontinuum generation was observed as …

Construction Of A Hyperspectral Camera Using Off-The-Shelf Parts And 3d-Printed Parts, Connor Heo

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences (ACSPS) is working together with the Mechanical Engineering Department to build a modifiable camera with 3D-printed parts and off-the-shelf parts (sourced from Edmund Optics and Amazon). The design is to be readily changeable, primarily with the 3D printed parts, as to accommodate new ideas and functionalities in the future. Ultimately, the camera should be relatively cheap while maintaining functionality for proposed use cases. Earlier versions of the design will be tested extensively and rapidly updated in the ACSPS labs with benchtop testing. This will involve subjects with both visible and infrared emissions, …

Single Metalens For Generating Polarization And Phase Singularities Leading To A Reverse Flow Of Energy, Victor V. Kotlyar, Anton G. Nalimov, Sergey S. Stafeev, Liam O'Faolain

Cappa Publications

Using Jones matrices and vectors, we show that a metasurface-based optical element composed of a set of subwavelength diffraction gratings, whose anisotropic transmittance is described by a matrix of polarization rotation by angle m, where is the polar angle, generate an mth order azimuthally or radially polarized beam, when illuminated by linearly polarized light, or an optical vortex with topological charge m, when illuminated by circularly polarized light. Such a converter performs a spin–orbit transformation, acting similarly to a liquid-crystal half-wave plate. Using the FDTD-aided numerical simulation, we show that uniform linearly or circularly polarized light passing through the …

Subwavelength Grating-Based Spiral Metalens For Tight Focusing Of Laser Light, Victor V. Kotlyar, Sergey S. Stafeev, Anton G. Nalimov, Liam O'Faolain

Cappa Publications

In this paper, we investigate a 16-sector spiral metalens fabricated on a thin film (130 nm) of amorphous silicon, consisting of a set of subwavelength binary diffractive gratings and with a numerical aperture that is close to unity. The metalens converts linearly polarized incident light into an azimuthally polarized optical vortex and focuses it at a distance approximately equal to the wavelength of the incident light, k ¼ 633 nm. Using a scanning near-field optical microscope, it is shown experimentally that the metalens forms an elliptical focal spot with diameters smaller than the diffraction limit: FWHMx ¼ 0.32k (60.03k) and …

Optical Vortex And Poincaré Analysis For Biophysical Dynamics, Anindya Majumdar

Dissertations, Master's Theses and Master's Reports

Coherent light - such as that from a laser - on interaction with biological tissues, undergoes scattering. This scattered light undergoes interference and the resultant field has randomly added phases and amplitudes. This random interference pattern is known as speckles, and has been the subject of multiple applications, including imaging techniques. These speckle fields inherently contain optical vortices, or phase singularities. These are locations where the intensity (or amplitude) of the interference pattern is zero, and the phase is undefined.

In the research presented in this dissertation, dynamic speckle patterns were obtained through computer simulations as well as laboratory setups …

Opticks:, Fyodor Andreievich Shiryaev

Senior Projects Spring 2019

Senior Project submitted to The Division of Arts of Bard College.

Spectroscopy Of Neon For The Advanced Undergraduate Laboratory, H. C. Busch, M. B. Cooper, C. I. Sukenik

Physics Faculty Publications

We describe a spectroscopy experiment, suitable for upper-division laboratory courses, that investigates saturated absorption spectroscopy and polarization spectroscopy in a neon discharge. Both experiments use nearly identical components, allowing students to explore both techniques in a single apparatus. Furthermore, because the wavelength of the laser is in the visible part of the spectrum (640 nm), the experiment is well-suited for students with limited experience in optical alignment. The labs nicely complement a course in atomic or plasma physics, provide students with the opportunity to gain important technical skills in the area of optics and lasers, and can provide an introduction …

Fast Objective Coupled Planar Illumination Microscopy, Cody Jonathan Greer

Arts & Sciences Electronic Theses and Dissertations

Among optical imaging techniques light sheet fluorescence microscopy stands out as one of the most attractive for capturing high-speed biological dynamics unfolding in three dimensions. The technique is potentially millions of times faster than point-scanning techniques such as two-photon microscopy. This potential is especially poignant for neuroscience applications due to the fact that interactions between neurons transpire over mere milliseconds within tissue volumes spanning hundreds of cubic microns. However current-generation light sheet microscopes are limited by volume scanning rate and/or camera frame rate. We begin by reviewing the optical principles underlying light sheet fluorescence microscopy and the origin of these …

Techniques For Improved Space Object Detection Performance From Ground-Based Telescope Systems Using Long And Short Exposure Images, David J. Becker

Theses and Dissertations

Space object detection is of great importance in the highly dependent yet competitive and congested space domain. Detection algorithms employed play a crucial role in fulfilling the detection component in the space situational awareness mission to detect, track, characterize and catalog unknown space objects. Many current space detection algorithms use a matched filter or a spatial correlator on long exposure data to make a detection decision at a single pixel point of a spatial image based on the assumption that the data follows a Gaussian distribution. This research focuses on improving current space object detection algorithms and developing new algorithms …

Thermally Stable Hybrid Cavity Laser Based On Silicon Nitride Gratings, Simone Iadanza, Andrei P. Bakoz, Praveen K. J. Singaravelu, Danilo Panettieri, Stefan Schulz, Ganga Chinna Rao Devarapu, Sylvain Guerber, Charles Baudot, Frédéric Boeuf, Stephen Hegarty, Liam O'Faolain

Cappa Publications

In this paper, we show the experimental results of a thermally stable Si3N4 external cavity (SiN EC) laser with high power output and the lowest SiN EC laser threshold to our knowledge. The device consists of a 250 μm sized reflective semiconductor optical amplifier butt-coupled to a passive chip based on a series of Si3N4 Bragg gratings acting as narrow reflectors. A threshold of 12 mA has been achieved, with a typical side-mode suppression ratio of 45 dB and measured power output higher than 3 mW. Furthermore, we achieved a mode-hop free-lasing regime in the range of 15–62 mA and …

Investigation Of Spin And Dip-Coating Phase Change Chalcogenide Materials As A Novel Technique For Coating And Functionalizing Conformal Optics, Paul Vecchio

Physics and Astronomy Summer Fellows

Chalcogenide glasses (ChGs) have excellent infrared (IR) transparency ranging up to 20 μm, large nonlinear refractive indices, and tailorable thermo-optic coefficients (dn/dT) that have great potential for applications in detectors, sensors, waveguides, imaging devices, photonic waveguides, acousto-optics, and optical devices. Spin and dip coating ChGs from solution is a low-cost, simple, and scalable method for depositing films over a large area. In this study, we utilize the novel approach of spin and dip coating to create thin ChG films of arsenic trisulfide (As₂S₃) and arsenic selenide (As₂Se₃). To realize the full potential …

Rotation Of Two-Petal Laser Beams In The Near Field Of A Spiral Microaxicon, S. S. Stafeev, Liam O'Faolain, M. V. Kotlyar

Cappa Publications

Using a spiral microaxicon with the topological charge 2 and NA = 0.6 operating at a 532-nm wavelength and fabricated by electron-beam lithography, we experimentally demonstrate the rotation of a two-petal laser beam in the near field (several micrometers away from the axicon surface). The estimated rotation rate is 55 °/mm and linearly dependent on the on-axis distance, with the theoretical rotation rate being 53 °/mm. The experimentally measured rotation rate is found to be linear and coincident with the simulation results only on the on-axis segment from 1.5 to 3 mm. The experimentally measured rotation rate is 66 °/mm …

Assembling And Characterizing The Efficiency Of An Injection Locked Laser System For Cold Neutral Atom Optical Traps, Alexandra Papa Crawford

Physics

Creating a quantum computer requires a system of particles that can be well-controlled to achieve quantum operations. We need a large array of these particles – called qubits – with long coherence times, which can be initialized, operated on by single and two qubit gates, and read out. For neutral atoms, the qubit states are stable ground states that interact minimally with the environment, leading to long coherence times. Experimentally, the qubits are manipulated using carefully timed laser beam pulses with controlled frequency and intensity, but the outstanding issue for optically trapping cold atoms is finding a light pattern that …

Analysis Of The Red And Green Optical Absorption Spectrum Of Gas Phase Ammonia, Nikolai F. Zobov, Phillip A. Coles, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Robert J. Hargreaves, Peter F. Bernath, Jonathan Tennyson, Sergei N. Yurchenko, Oleg L. Polyansky

Chemistry & Biochemistry Faculty Publications

Room temperature NH₃ absorption spectra recorded at the Kitt Peak National Solar Observatory in 1980 are analyzed. The spectra cover two regions in the visible: 15,200 - 15,700 cm^-1 and 17,950 - 18,250 cm^-1. These high overtone rotation-vibration spectra are analyzed using both combination differences and variational line lists. Two variational line lists were computed using the TROVE nuclear motion program: one is based on an ab initio potential energy surface (PES) while the other used a semi-empirical PES. Ab initio dipole moment surfaces are used in both cases. 95 energy levels with J = 1 …

R&D Of A High-Performance Dirc Detector For A Future Electron-Ion Collider, Stacey Lee Allison

Physics Theses & Dissertations

An Electron-Ion Collider (EIC) is proposed as the next big scientific facility to be built in the United States, costing over $1 billion in design and construction. Each detector concept for the electron/ion beam interaction point is integrated into a large solenoidal magnet. The necessity for excellent hadronic particle identification (pion/kaon/proton) in the barrel region of the solenoid has pushed research and development (R&D) towards a new, high-performance Detection of Internally Reflected Cherenkov light (DIRC) detector design. The passage of a high energy charged particle through a fused silica bar of the DIRC generates optical Cherenkov radiation. A large fraction …

Optical Physics Of Rifle Scopes, Ryan Perry

Physics

Optical systems are typically consist of multiple lenses and mirrors and are used in a wide variety of fields. While there exist a variety of setups, there are a few key concepts that are at the core of all of them. These could be used from the most advanced scientific research to a simple magnifying glass. They are also used in industry and consumer products such as glasses and cameras. We are going to go over these key concepts and show how they apply to telescopes, or more specifically rifle scopes. First, we will go over Snell's Law of refraction …

Studies In Mesoscopics And Quantum Microscopies, Zhenghao Ding, Gabriel C. Spalding

Honors Projects

This thesis begins with a foundational section on quantum optics. The single-photon detectors used in the first chapter were obtained through the Advanced Laboratory Physics Association (ALPhA), which brokered reduced cost for educational use, and the aim of the single-photon work presented in Chapter 1 is to develop modules for use in Illinois Wesleyan's instructional labs beyond the first year of university. Along with the American Association of Physics Teachers, ALPhA encourages capstone-level work, such as Chapter 1 of this honors thesis, which is explicitly designed to play the role of passing on, to a next generation of physics majors, …

Key Encryption Through Quantum Optics, Madison Durrance, Zach Galberd, Abbey Savage, Tristan Cabrera, Josh Hoffman

Georgia College Student Research Events

Cryptography has been around since the dawn of human civilization to send private messages for commercial, military, and political purposes. Some of the most important ciphers are the Vigenère cipher, the enigma, and the more modern RSA. Because of the development of the internet, private encryption has also become increasingly more important. The weakest link of encryption is the key creation and key distribution. A key is needed to encrypt and decipher codes and is needed by both the user and sender. A solution to this problem is the generation of quantum key distributions. In our experiment, we are now …

Optical Forces Generated By Plasmonic Nanostructures, Matthew A. Moocarme

Dissertations, Theses, and Capstone Projects

For millennia, scientists have sought to uncover the secrets of what holds the world together. Optical physicists are often at the forefront, unraveling material properties through investigations of light-matter interactions. As the field has progressed, the smallest unit at which matter can be probed and manipulated has subsequently decreased. The resulting sub-field nanophotonics- which reflects the processing of light at the nanoscale- has blossomed into a vast design space for both applied and theoretical researchers. Plasmonics, the phenomena by which the electron-density of a material oscillates in response to incident electromagnetic radiation, is a subject that has excited nanophotonics researchers …

Dynamic Holography In Semiconductors And Biomedical Optics, Hao Sun

Open Access Dissertations

Three-dimensional scanning and display are rapidly-advancing new technologies with important commercial drivers such as 3D printing and remote imaging for big data applications. Holography is a natural approach to recording and displaying three-dimensional information because it uses phase-sensitive interferometry to record interference patterns when a reference beam encounters coherent light arriving from an object. The 3D information is contained in the values of wave optics. Holography is a broad field that goes beyond recording and displaying. For instance, holographic optical elements, which take advantage of holographic imaging principles, perform the functions of lenses, gratings or mirrors. Holographic interferometry is also …

Wave Propagation And Imaging In Structured Optical Media, Zun Huang

Open Access Dissertations

Structured optical media, usually characterized by periodic patterns of inhomogeneities in bulk materials, provide a new approach to ultimate control of wave propagation with possible practical applications: from distributed feedback lasers by diffraction gratings, to highly nonlinear performance for super-continuum generation, to fiber-optic telecommunications by microstructured photonic crystal fibers, to invisibility cloaking, to super-resolution imaging with metamaterials etc.

In particular, structured optical media allow to manipulate the wave propagation and dispersion. In this thesis, we focus on engineering the propagation phase dispersion by modulating the compositions and dimensions of the periodic elements. By tailoring the dispersion in momentum space, we …

Transmission Of Focused Picosecond Light Pulse Through Multimode Fibers, Yin Cen

Dissertations, Theses, and Capstone Projects

This thesis focuses on a technique of delivering spatially focused and temporally compressed picosecond laser pulses through multimode fibers. This study was inspired by recent success in focusing light through optically diffusive media of which multimode fibers were a special case in terms of causing scrambled phase distribution in the transmitted light. The approach involved controlling the phase distribution of incoming beam using a deformable mirror prior to its entry into the multimode fiber in order to achieve constructive interference at selected spots in the output. With phase control, the intensity of the focused light at the output can be …

Study Of Plasmonic Properties Of The Gold Nanorods In The Visible To Near Infrared Light Regime, Pijush Kanti Ghosh

Graduate Theses and Dissertations

Nanostructures of noble metals show unique plasmonic behavior in the visible to near-infrared light range. Gold nanostructures exhibit a particularly strong plasmonic response for these wavelengths of light. In this study we have investigated optical enhancement and absorption of gold nanorods with different thickness using finite element method simulations. This study reports on the resonance wavelength of the sharp-corner and round-corner rectangles of constant length 100 nm and width 60 nm. The result shows that resonance wavelength depends on the polarization of the incident light; there also exists a strong dependence of the optical enhancement and absorption on the thickness …