Optics Commons^™

Symmetries, Zero Modes And Light Transport In Non-Hermitian Photonics, Jose David Hernandez Rivero

Dissertations, Theses, and Capstone Projects

We approach some fundamental aspects of photonic dissipative systems treated by a non-Hermitian theory. Inspired by the possibilities provided by some major non-Hermitian symmetries, we study systematically the properties of the novel pseudochirality, pseudo-anti-Hermiticity, and supersymmetry. We analyze other aspect of photonics, the zero mode, which has a profound connection to non-Hermitian physics. We propose a scheme to realize a zero mode that exists even in the absence of symmetries. Finally, we approach light transport in non-Hermitian photonic systems, where the introduction of gain and loss can modify drastically the propagation speed of wavepackets.

Developing A Data Acquisition System For Use In Cold Neutral Atom Traps, Jonathan E. Fuzaro Alencar

Physics

The rising interest in quantum computing has led to new quantum systems being developed and researched. Among these are trapped neutral atoms which have several desirable features and may be configured and operated on using lasers in an optical lattice. This work describes the development of a new data acquisition system for use in tuning lasers near the precise hyperfine transition frequencies of Rb 87 atoms, a crucial step in the functionality of a neutral atom trap. This improves on previous implementations that were deprecated and limited in laser frequency sweep range. Integration into the experiment was accomplished using an …

Maximum Trapping Focal Length In Photophoretic Trap For 3d Imaging Systems, Jason M. Childers

Electrical Engineering

This product is a photophoretic trapping system which allows varying focal lengths to test which focal lengths are possible for trapping toner particles. This system establishes that there exists a maximum trapping distance limitation and is the first time the effect of focal length is studied in a photophoretic trapping system. Increasing photophoretic trapping focal length is necessary for improving this technology as a 3D display. The 3D imaging technology is realized by dragging a microscopic (micrometer-scale) particles with a laser beam to trace an image. This technology can display fully colored and high-resolution 3D images visible from almost any …

Methods For Focal Plane Array Resolution Estimation Using Random Laser Speckle In Non-Paraxial Geometries, Phillip J. Plummer

Theses and Dissertations

The infrared (IR) imaging community has a need for direct IR detector evaluation due to the continued demand for small pixel pitch detectors, the emergence of strained-layer-super-lattice devices, and the associated lateral carrier diffusion issues. Conventional laser speckle-based modulation transfer function (MTF) estimation is dependent on Fresnel propagation and a wide-sense-stationary input random process, limiting the use of this approach for lambda (wavelength)-scale IR devices. This dissertation develops two alternative methodologies for speckle-based resolution evaluation of IR focal plane arrays (FPAs). Both techniques are formulated using Rayleigh-Sommerfield electric field propagation, making them valid in the non-paraxial geometries dictated for resolution …

Observation And Control Of Photoemission And Electric Field Enhancement Of Plasmonic Antennas Through Photoemission Electron Microscopy, Christopher M. Scheffler

Dissertations and Theses

Photoemission electron microscopy (PEEM) is an imaging method which uses electrons excited through the photoelectric effect to characterize a sample surface with nanometer-level resolution. In PEEM, a high intensity laser excites electrons from the surface of the material and electron optics are used to form an image from the intensity and spatial distribution of the photoemission from the sample. The goal of this research was to study and maximize light confinement, which was accomplished using plasmonic nanostructures. Surface plasmons represent oscillations in the electron density of a material and can occur along the transition interface between a metal and a …

Numerical Methods For Optimal Transport And Optimal Information Transport On The Sphere, Axel G. R. Turnquist

Dissertations

The primary contribution of this dissertation is in developing and analyzing efficient, provably convergent numerical schemes for solving fully nonlinear elliptic partial differential equation arising from Optimal Transport on the sphere, and then applying and adapting the methods to two specific engineering applications: the reflector antenna problem and the moving mesh methods problem. For these types of nonlinear partial differential equations, many numerical studies have been done in recent years, the vast majority in subsets of Euclidean space. In this dissertation, the first major goal is to develop convergent schemes for the sphere. However, another goal of this dissertation is …

Tailored Resonant Waveguide Gratings For Augmented Reality, Matt Markowitz, Michele Cotrufo, You Zhou, Karl Stensvad, Craig Schard, Adam C. Overvig, Andrea Alù

Advanced Science Research Center

We explore the use of tailored resonant waveguide gratings (RWG) embedded in a glass-like matrix as angularly tolerant tri-band reflection filters under oblique excitation. Through inverse design we optimize 1D grating structures to support multi-frequency narrow- band resonances in an otherwise transparent background, ideally suited for augmented reality applications. In particular, we show theoretically and experimentally that a single RWG can be tailored to provide reflection levels larger than 50% under p-polarized excitation at three distinct wavelengths of choice, over a narrow bandwidth and within a substantial angular range around 58° incidence, while simultaneously eliminating ghost reflections from the glass/air …

Event-Based Imaging Polarimeter, Michael R. Hawks, Michael L. Dexter

Faculty Publications

The design and initial experimental results from an event-based, rotating-polarizer, imaging polarimeter are presented. The speed of division-of-time imaging systems is traditionally constrained by the frame rate of the focal plane sensor and the need to sample several polarization angles during rotation. The asynchronous event reporting of event-based cameras (EBCs) frees these constraints but introduces challenges. The Stokes vectors used to describe polarization are based on irradiance, but EBCs are inherently change-detection systems that struggle to estimate irradiance. Two methods of estimating the polarization state without first recovering irradiance images are presented and compared. The DAVIS 346 sensor enables simultaneous …

Monitoring Bacteria Cultures Using Near Infrared (Nir) Binary Spectronephelometry (Bsn), Raman Spectra And Principal Component Analysis (Pca), Steven Ortiz

Dissertations - ALL

Current noninvasive methods cannot continuously and simultaneously monitor the concentrations of cells and media components that define the state of native bacterial cultures, because of changing turbidity. A new technique, binary spectronephelometry (BSN) has the same or better sensitivity and precision for population monitoring as optical density at 600nm (OD600), while simultaneously measuring metabolic processes. The BSN algorithm uses laser induced emission to probe mildly turbid media i.e., propagation of light occurs in the single scattering regime. A BSN "training set" associates a grid of elastic emission measurements, comprising Rayleigh and Mie scattering, and inelastic emission measurements, comprising fluorescence and …

Examination Of Ionization In Cesium Diode Pumped Alkali Lasers With An Ion Chamber Diagnostic, Benjamin Oliker

Optical Science and Engineering ETDs

Diode pumped alkali lasers (DPALs) are leading candidates for future high power applications, with many potential utilities for the military, aerospace, communications, and scientific diagnostics. A critical step in their development is measurement and understanding of unwanted ionization processes that occur inside the laser, which decrease efficiency, reduce the usable alkali population, and increase heat load. In this dissertation, direct measurement of the ionization rate of a cesium DPAL gain medium are made for the first time, via application of an ion chamber diagnostic. Results will demonstrate that the rate of ionization is slow compared to pump absorption, with a …

Low-Temperature Luminescence Spectrum Of A Fine-Grained Cdte Layer In A Film Heterostructure N-Cds/P-Cdte, N. Kh Yuldashev

Scientific-technical journal

It is shown that the spectrum of low-temperature (4.2 K) edge photoluminescence of a thin and fine-grained (h,d=1mkm) polycrystalline CdTe layer in an n-CdS/p-CdTe film heterostructure upon frontal excitation by an Ar+ laser with a flux power of -4.8 mW/mm² consists of the dominant А - lines of intrinsic (e-h) emission with a half-width6-8 meV and a short-wavelength shift 30 meV of the red boundary relative to Eg , its LO-phonon repetition (B-lines, 40meV) and a broad D-line (40 meV) of surface-interface luminescence with a maximum at a frequency of 150eV. The back illumination of the photoresistive CdS layer …

Monolithically Integrated Microscale Pressure Sensor On An Optical Fiber Tip, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) pressure sensor includes an optical fiber and a three-dimensional microscopic optical enclosure. The three-dimensional microscopic optical enclosure includes tubular side walls having lateral pleated corrugations and attached to a cleaved tip of the optical fiber to receive a light signal. An optically reflecting end wall is distally engaged to the tubular side walls to enclose a trapped quantity of gas that longitudinally positions the optically reflecting end wall in relation to ambient air pressure, changing a distance traveled by a light signal reflected back through the optical fiber.

Hinged Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of the optical fighter using a two-photon polymerization process on a photosensitive polymer by a three-dimensional micromachining device. The three-dimensional microscopic optical structure having a hinged optical layer pivotally connected to a distal portion of a suspended structure. A reflective layer is deposited on a mirror surface of the hinged optical layer while in an open position. The hinged optical layer is subsequently positioned in the closed position to align the mirror surface to at least partially reflect a light signal back …

Optical Vortex Generation Using 3-D Printed Reflection And Transmission Holograms, Tara R. Crowe

Honors Capstone Projects and Theses

No abstract provided.

Automation Of The Transition Identification Procedure For Trapping Rubidium Atoms In A Magneto-Optical Trap, Michael P. Fletcher

Physics

The words “quantum computer” often conjure images of science fiction and unrealistic technology from an impossible future. Some may even believe that they aren’t real or are only theoretical. The truth is that quantum computers are real, tangible systems with real life uses and rooted in credible scientific research. Today, many groups of scientists collaborate on research into better ways of implementing and improving quantum computing techniques. This paper will be addressing the systems required and phenomena used to achieve neutral atom trapping for quantum computation. This thesis will outline the physical phenomena involved with the frequency tuning process for …

Porous Silicon Photonics For Label-Free Interferometric Biosensing And Flat Optics, Tahmid Hassan Talukdar

All Dissertations

This dissertation uses porous silicon as a material platform to explore novel optical effects in three domains: (i) It studies dispersion engineering in integrated waveguides to achieve high performance group index sensing. With proper design parameters, the sensor waveguides can theoretically achieve 6 times larger group index shift compared to the actual bulk effective refractive index shift. We demonstrate the guided mode confinement factor to be a key parameter in design and implementation of these waveguides. (ii) It explores multicolor laser illumination to experimentally demonstrate perceptually enhanced colorimetric sensing, overcoming the limitations faced by many contemporary colorimetric sensors. Our technique …

Optimization Of Modular, Long-Range, Ultra-Fast Optical Tweezers With Fluorescence Capabilities For Single-Molecule And Single-Cell Based Biophysical Measurements, Subash C. Godar

All Dissertations

An Optical tweezer is a tightly focused laser beam that applies and senses precise and localized optical force to a dielectric microsphere and offers a unique and effective tool for manipulating the single cell or cell components, including nucleotides and dynein motor proteins. Here, I used highly stabilized optomechanical components and ultra-sensitive detection modules to significantly improve the measurement capabilities over a wide range of temporal and spatial scales. I combined the optical tweezer-based force spectroscopy technique with fluorescence microscopy to develop an integrated high-resolution force-fluorescence system capable of measuring displacements at sub-nanometer, forces at sub-piconewton over a temporal range …

Experimental Investigation Of All-Optical Production Of Metastable Krypton, Joshua Carl Frechem

Physics Theses & Dissertations

Metastable production of noble gases requires significant energy due to their filled valence shells. These transitions from the ground state are in the vacuum ultraviolet and extreme ultraviolet, which are relatively inaccessible to lasers. This necessitates the use of either electron/ion bombardment via inefficient glow discharges or the use of high-power lasers and nonlinear processes. The all-optical production efficiency using these high-power lasers promises to be orders of magnitude higher than glow discharges, but far more costly. This work looks to improve all-optical production of metastable krypton (Kr*) through the use of a commercially available vacuum ultraviolet lamp with a …

Design And Characterization Of Frequency Tripling Mirrors, Amir Khabbazi Oskouei

Optical Science and Engineering ETDs

Aperiodic stacks of dielectric low- and high-index films can be designed to enhance third-harmonic generation (THG) in reflection of near infrared laser pulses using computer optimization. Numerical and analytical results suggest that the TH energy increases rapidly with increasing number of films and the ratio of the high and low index.

Our optical matrix based THG model that takes into account the full pulse bandwidth predicts conversion efficiencies of about 7% for transform-limited Gaussian pulse bandwidths of 16 nm for mirrors with 45 layers, which exceed those expected from periodic designs. Stability against film thickness fluctuations expected from the deposition …

3d Flow Field Measurements Outside Nanopores, Jeffrey Mc Hugh, Alice L. Thorneywork, Kurt Andresen, Ulrich F. Keyser

Physics and Astronomy Faculty Publications

We demonstrate a non-stereoscopic, video-based particle tracking system with optical tweezers to study fluid flow in 3D in the vicinity of glass nanopores. In particular, we used the quadrant interpolation algorithm to extend our video-based particle tracking to displacements out of the trapping plane of the tweezers. This permitted the study of flow from nanopores oriented at an angle to the trapping plane, enabling the mounting of nanopores on a micromanipulator with which it was then possible to automate the mapping procedure. Mapping of the voltage driven flow in 3D volumes outside nanopores revealed polarity dependent flow fields. This is …