Optics Commons^™

Comparative Analysis Of Reconstructed Image Quality In A Simulated Chromotomographic Imager, Ryan L. Tervo

Theses and Dissertations

A hyperspectral chromotomographic instrument has been developed to determine the spatial and spectral distribution of a target. It does this by recording the dispersed images produced by a rotating direct vision prism with a high speed camera. The recorded images are processed through a tomographic reconstruction algorithm to produce a reconstructed hypercube. A physics-based system model was developed to investigate three areas. The first was how the prism angle selection and range of angles used impacted the reconstructed image quality. The second was an assessment of a new iterative reconstruction algorithm developed to remove artifacts produced in the Back Projection …

Range Finding With A Plenoptic Camera, Robert A. Raynor

Theses and Dissertations

The plenoptic camera enables simultaneous collection of imagery and depth information by sampling the 4D light field. The light field is distinguished from data sets collected by stereoscopic systems because it contains images obtained by an N by N grid of apertures, rather than just the two apertures of the stereoscopic system. By adjusting parameters of the camera construction, it is possible to alter the number of these `subaperture images,' often at the cost of spatial resolution within each. This research examines a variety of methods of estimating depth by determining correspondences between subaperture images. A major finding is that …

Monitoring Atom Traps For Neutral Atom Quantum Computing, Taylor Shannon

Physics

To increase computing power for numerous practical advantages, scientists are actively researching the field of quantum computing. Neutral atom quantum computing is a promising avenue towards building a quantum computer that satisfies four of the five DiVincenzo criteria. This involves a magneto-optical trap to cool the atoms and move them to a cloud in the center of a vacuum chamber. Then laser light will be shone through an array of pinholes to trap the atoms in an array of dipole traps. In order to ensure the atoms are trapped, I have set up an imaging system that consists of a …

Development Of High-Purity Optical Grade Single-Crystal Cvd Diamond For Intracavity Cooling, Andrew M. Bennett, Benjamin J. Wickham, Harpreet K. Dhillon, Ying Chen, Scott Webster, Giorgio Turri, Michael Bass

Publications

Microwave assisted chemical vapour deposited bulk diamond products have been used in a range of high power laser systems, due to low absorption across a range of wavelengths and exceptional thermal properties. However the application of polycrystalline products has frequently been limited to applications at longer wavelengths or thermal uses outside of the optical path due to the birefringence and scatter that are intrinsic properties of the polycrystalline materials. However, there are some solid state structures, including thin disc gain modules and amplifiers, that will gain significantly in terms of potential output powers if diamond could be used as a …

Using Acrylamide Based Photopolymers For Fabrication Of Holographic Optical Elements In Solar Energy Applications, Hoda Akbari, Izabela Naydenova, Suzanne Martin

Articles

A holographic device is under development that aims to improve light collection in solar cells. The aim is to explore the potential of using photopolymer Holographic Optical Elements (HOE) to collect light from a moving source, such as the sun, and re-direct it for concentration by a holographic lens.. A working range of 45 degrees is targeted for such a device to be useful in solar applications without tracking. A photopolymer HOE is capable of efficiently re-directing light, but the angular selectivity of a single grating is usually of the order of one degree at the thicknesses required for high …

A Low-Power Optical Electron Switch, Wayne Cheng-Wei Huang, Roger Bach, Peter Beierle, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

An electron beam is deflected when it passes over a silicon-nitride surface, if the surface is illuminated by a low-power continuous-wave diode laser. A deflection angle of up to 1.2 mrad is achieved for an electron beam of 29 μrad divergence. A mechanical beam-stop is used to demonstrate that the effect can act as an optical electron switch with a rise and fall time of 6 μs. Such a switch provides an alternative means to control electron beams, which may be useful in electron lithography and microscopy.

On-Chip Multi 4-Port Optical Circulators, Ramy El-Ganainy, Miguel Levy

Department of Physics Publications

We present a new geometry for on-chip optical circulators based on waveguide arrays. The optical array is engineered to mimic the Fock space representation of a noninteracting two-site Bose–Hubbard Hamiltonian. By introducing a carefully tailored magnetooptic nonreciprocity to these structures, the array operates in the perfect transfer and surface Bloch oscillation modes in the forward and backward propagation directions, respectively. We show that an array made of ð2N þ 1Þ waveguide channels can function as N 4-port optical circulators with very large isolation ratios and low forward losses. Numerical analysis using beam propagation method indicates a large bandwidth of operation.

Investigation Of Profiled Beam Propagation Through A Turbulent Layer And Temporal Statistics Of Diffracted Output For A Modified Von Karman Phase Screen, Monish Ranjan Chatterjee, Fathi H.A. Mohamed

Electrical and Computer Engineering Faculty Publications

Gaussian beam propagation through a turbulent layer has been studied using a split-step methodology. A modified von Karman spectrum (MVKS) model is used to describe the random behavior of the turbulent media. Accordingly, the beam is alternately propagated (i) through a thin Fresnel layer, and hence subjected to diffraction; and (ii) across a thin modified von Karman phase screen which is generated using the power spectral density (PSD) of the random phase obtained via the corresponding PSD of the medium refractive index for MVKS turbulence.

The random phase screen in the transverse plane is generated from the phase PSD by …

Numerical Inversion And Assessment Of 2d Laplace Transforms Using The Brancik Algorithm And Its Use In 3d Holography, Monish Ranjan Chatterjee, Le Feng

Electrical and Computer Engineering Faculty Publications

An analytic examination of 3D holography under a 90° recording geometry was carried out earlier in which 2D spatial Laplace transforms were introduced in order to develop transfer functions for the scattered outputs under readout [1,2].

Thereby, the resulting reconstructed output was obtained in the 2D Laplace domain whence the spatial information would be found only by performing a 2D Laplace inversion. Laplace inversion in 2D was attempted by testing a prototype function for which the analytic result was known using two known inversion algorithms, viz., the Brancik and the Abate [2]. The results indicated notable differences in the 3D …

Second-Harmonic Double-Resonance Cones In Dispersive Hyperbolic Metamaterials, Domenico De Ceglia, Maria Antonietta Vincenti, Salvatore Campione, Filippo Capolino, Joseph W. Haus, Michael Scalora

Electrical and Computer Engineering Faculty Publications

We study the formation of second-harmonic double-resonance cones in hyperbolic metamaterials. An electric dipole on the surface of the structure induces second-harmonic light to propagate into two distinct volume plasmon-polariton channels: a signal that propagates within its own peculiar resonance cone and a phase-locked signal that is trapped under the pump's resonance cone. Metamaterial dispersion and birefringence induce a large angular divergence between the two volume plasmon polaritons, making these structures suitable for subwavelength second- and higher-harmonic imaging microscopy.

Planar Waveguide Structures For Post-Edfa Broadband Near Infrared Optical Amplifiers, Islam Hoxha

Dissertations, Theses, and Capstone Projects

This thesis reports on optical gain of up to 5.7 dB from a planar waveguide with core made of tetravalent chromium-doped calcium germanate single crystal.

Avoiding Loopholes With Hybrid Bell-Leggett-Garg Inequalities, Justin Dressel, Alexander N. Korotkov

Mathematics, Physics, and Computer Science Faculty Articles and Research

By combining the postulates of macrorealism with Bell locality, we derive a qualitatively different hybrid inequality that avoids two loopholes that commonly appear in Leggett-Garg and Bell inequalities. First, locally invasive measurements can be used, which avoids the “clumsiness” Leggett-Garg inequality loophole. Second, a single experimental ensemble with fixed analyzer settings is sampled, which avoids the “disjoint sampling” Bell inequality loophole. The derived hybrid inequality has the same form as the Clauser-Horne-Shimony-Holt Bell inequality; however, its quantum violation intriguingly requires weak measurements. A realistic explanation of an observed violation requires either the failure of Bell locality or a preparation conspiracy …

Improving Einstein–Podolsky–Rosen Steering Inequalities With State Information, James Schneeloch, Curtis J. Broadbent, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We discuss the relationship between entropic Einstein–Podolsky–Rosen (EPR)-steering inequalities and their underlying uncertainty relations along with the hypothesis that improved uncertainty relations lead to tighter EPR-steering inequalities. In particular, we discuss how using information about the state of a quantum system affects oneʼs ability to witness EPR-steering. As an example, we consider the recent improvement to the entropic uncertainty relation between pairs of discrete observables (Berta et al., 2010 [10]). By considering the assumptions that enter into the development of a steering inequality, we derive correct steering inequalities from these improved uncertainty relations and find that they are identical to …

Characterization Of Polarized Synchrotron Light, Britny N. Delp, Jeff Corbett

STAR Program Research Presentations

The Stanford Synchrotron Radiation Light accelerates electrons around a 234-meter circumference ring at relativistic speeds. The x-ray radiation produced by this process is used in many fields of science ranging from materials science to medicine.

This project seeks to measure the polarization of the 532 nanometer wavelength component in the visible light beam emitted from the SPEAR-3 synchrotron as a function of vertical position. The beam was focused through a lens, then passed through a 532 nm band pass filter and a polarizer mounted on a rotating stand. The beam power was measured as a function of vertical position and …

Multi-Wavelength Speckle Reduction For Laser Pico-Projectors Using Diffractive Optics, Weston H. Thomas

Dissertations, Master's Theses and Master's Reports - Open

Personal electronic devices, such as cell phones and tablets, continue to decrease in size while the number of features and add-ons keep increasing. One particular feature of great interest is an integrated projector system. Laser pico-projectors have been considered, but the technology has not been developed enough to warrant integration. With new advancements in diode technology and MEMS devices, laser-based projection is currently being advanced for pico-projectors. A primary problem encountered when using a pico-projector is coherent interference known as speckle. Laser speckle can lead to eye irritation and headaches after prolonged viewing. Diffractive optical elements known as diffusers have …

A Photonic Crystal Fiber Based Polarimetric Sensor For Cure Monitoring Of Magneto-Rheological Smart Composite Material, Manjusha Ramakrishnan, Ginu Rajan, Yuliya Semenova, Y. Zhou, Stephen Jerrams, Gerald Farrell

Articles

A buffer stripped high birefringent photonic crystal fibre based polarimetric sensor is developed for monitoring the curing process of magnetorheological elastomer (MRE) smart composite material. Using the developed sensor, different phases of the MRE curing process are clearly visible from the phase shift variation of the embedded polarisation maintaining photonic crystal fibre (PM-PCF) sensor. During the curing process, the buffer stripped PM-PCF exhibits a stress/strain induced phase shift variation from 0 to 1.98 rad. This is a significantly large phase change, which can be used to very clearly identify the different stages in the curing process. For comparison, a fibre …

Experimental Realization Of Slowly Rotating Modes Of Light, Fangzhao A. An

HMC Senior Theses

Beams of light can carry spin and orbital angular momentum. Spin angular momentum describes how the direction of the electric field rotates about the propagation axis, while orbital angular momentum describes the rotation of the field amplitude pattern. These concepts are well understood for monochromatic beams, but previous theoretical studies have constructed polychromatic superpositions where the connection between angular momentum and rotation of the electric field becomes much less clear. These states are superpositions of two states of light carrying opposite signs of angular momentum and slightly detuned frequencies. They rotate at the typically small detuning frequency and thus we …

Cascaded Plasmon Resonances For Enhanced Nonlinear Optical Response, Seyfollah Toroghi

Electronic Theses and Dissertations

The continued development of integrated photonic devices requires low-power, small volume all-optical modulators. The weak nonlinear optical response of conventional optical materials requires the use of high intensities and large interaction volumes in order to achieve significant light modulation, hindering the miniaturization of all-optical switches and the development of lightweight transmission optics with nonlinear optical response. These challenges may be addressed using plasmonic nanostructures due to their unique ability to confine and enhance electric fields in sub-wavelength volumes. The ultrafast nonlinear response of free electrons in such plasmonic structures and the fast thermal nonlinear optical response of metal nanoparticles, as …

High Resolution Time-Resolved Imaging System In The Vacuum Ultraviolet Region, Yuseong Jang

Electronic Theses and Dissertations

High-power debris-free vacuum ultraviolet (VUV) light sources have applications in several scientific and engineering areas, such as high volume manufacturing lithography and inspection tools in the semiconductor industry, as well as other applications in material processing and photochemistry. For the past decades, the semiconductor industry has been driven by what is called "Moore's Law". The entire semiconductor industry relies on this rule, which requires chip makers to pack transistors more tightly with every new generation of chips, shrinking the size of transistors. The ability to solve roadmap challenges is, at least partly, proportional to our ability to measure them. The …

Injection-Locked Vertical Cavity Surface Emitting Lasers (Vcsels) For Optical Arbitrary Waveform Generation, Sharad Bhooplapur

Electronic Theses and Dissertations

Complex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse-shaping, with the goal of making non-periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance of LADAR systems, high-capacity optical telecommunications and ultra wideband signals processing. In this work, an array of Vertical Cavity Surface Emitting Lasers (VCSELs) are used as modulators, by injection-locking each VCSEL to an individual …

Large Area Conformal Infrared Frequency Selective Surfaces, Jeffrey D'Archangel

Electronic Theses and Dissertations

Frequency selective surfaces (FSS) were originally developed for electromagnetic filtering applications at microwave frequencies. Electron-beam lithography has enabled the extension of FSS to infrared frequencies; however, these techniques create sample sizes that are seldom appropriate for real world applications due to the size and rigidity of the substrate. A new method of fabricating large area conformal infrared FSS is introduced, which involves releasing miniature FSS arrays from a substrate for implementation in a coating. A selective etching process is proposed and executed to create FSS particles from crossed-dipole and square-loop FSS arrays. When the fill-factor of the particles in the …

Novel Gaas-Based Materials For Reconfigurable Electro-Modulated Lasers In Optical Interconnects, Jiri Thoma

Theses

With the rapid commercialization of personal computers and with the ever increasing desire for faster and larger data transfer, there is a strong need to increase network capacity. One solution is to replace standard metallic connections by optical fibers and full optical technologies. Although such technologies exist and are successfully employed in backbone connections, their complexities hinder a wider utilization toward end customers. Therefore, both manufacturing and operational costs are crucial. Integration of several optical components onto a single device chip is the key element. A simplified integration scheme bringing an additional cost reduction is also welcomed. This thesis presents …

Sensitivity Of Orbiting Jem-Euso To Large-Scale Cosmic-Ray Anisotropies, Peter B. Denton, Luis A. Anchordoqui, Andreas A. Berlind, Matthew Richardson, Thomas J. Weiler

Publications and Research

The two main advantages of space-based observation of extreme-energy (& 1019 eV) cosmic-rays (EECRs) over ground-based observatories are the increased field of view, and the all- sky coverage with nearly uniform systematics of an orbiting observatory. The former guarantees increased statistics, whereas the latter enables a partitioning of the sky into spherical harmonics. We have begun an investigation, using the spherical harmonic technique, of the reach of JEM- EUSO into potential anisotropies in the extreme-energy cosmic-ray sky-map. The technique is explained here, and simulations are presented. The discovery of anisotropies would help to identify the long-sought origin of EECRs.

Experimental Study And Analysis Of A Polymer Fiber Bragg Grating Embedded In A Composite Material, Ginu Rajan, Manjusha Ramakrishnan, Yuliya Semenova, Eliathamby Ambikairajah, Gerald Farrell, Gang-Ding Peng

Articles

The characteristics of polymer fiber Bragg gratings (FBGs) embedded in composite materials are studied in this paper and are compared with characteristics of their silica counterparts. A polymer FBG of 10 mm length which exhibits a peak reflected wavelength circa 1530 nm is fabricated and characterized for this purpose. A silica FBG with a peak reflected wavelength circa 1553 nm is also embedded in the composite material for a comparison study. The fabricated composite material sample with embedded sensors is subjected to temperature and strain changes and the corresponding effects on the embedded polymer and silica FBGs are studied. The …

Modification Of Plasmonic Nano Structures' Absorption And Scattering Under Evanescent Wave Illumination Above Optical Waveguides Or With The Presence Of Different Material Nano Scale Atomic Force Microscope Tips, Gazi Mostafa Huda

Theses and Dissertations--Electrical and Computer Engineering

The interaction of an evanescent wave and plasmonic nanostructures are simulated in Finite Element Method. Specifically, the optical absorption cross section (C_abs) of a silver nanoparticle (AgNP) and a gold nanoparticle (AuNP) in the presence of metallic (gold) and dielectric (silicon) atomic force microscope (AFM) probes are numerically calculated in COMSOL. The system was illuminated by a transverse magnetic polarized, total internally reflected (TIR) waves or propagating surface plasmon (SP) wave. Both material nanoscale probes localize and enhance the field between the apex of the tip and the particle. Based on the absorption cross section equation the author …

Diffraction-Based Techniques For High Contrast X-Ray Imaging, Lubna Naseem Peerzada

Legacy Theses & Dissertations (2009 - 2024)

Two X-ray diffraction based techniques for high contrast were explored to improve contrast in radiology: diffraction enhanced imaging (DEI) and coherent scatter imaging.

Experimental And Simulation Studies Of Printability Of Buried Euv Mask Defects And Study Of Euv Reflectivity Loss Mechanisms Due To Standard Euv Mask Cleaning Processes, Mihirkant Upadhyaya

Legacy Theses & Dissertations (2009 - 2024)

There's a big push for development and commercialization of extreme ultraviolet (EUV) lithography for high-volume semiconductor manufacturing of 14 nm half-pitch patterning and beyond. One of the primary concerns for making this a reality has been the ability to achieve defect-free masks. My study is focused on two aspects related to the performance degradation of the EUV masks namely EUV mask cleaning induced reflectivity loss mechanisms, and the buried multilayer phase defects in EUV masks.

Microwave Assisted Reconstruction Of Optical Interferograms For Distributed Fiber Optics Sensing & Characterization Of Pcb Dielectric Properties Using Two Striplines On The Same Board, Lei Hua

Masters Theses

"A new concept, the microwave-assisted reconstruction of an optical interferogram for distributed sensing, was developed to resolve both the position and reflectivity of each sensor along an optical fiber. This approach involves sending a microwave-modulated optical signal through cascaded fiber optic interferometers. The optical spectrum of each sensor can be reconstructed by sweeping the optical wavelength and detecting the modulation signal. A series of cascaded fiber optic extrinsic Fabry-Perot interferometric sensors was used to prove the concept. The microwave-reconstructed interferogram matched well with those recorded individually from a traditional optical spectrometer. The application of distributed strain measurement was also investigated. …

Multifunctional, Multimaterial Particle Fabrication Via An In-Fiber Fluid Instability, Joshua Kaufman

Electronic Theses and Dissertations

Spherical micro- and nano-particles have found widespread use in many various applications from paint to cosmetics to medicine. Due to the multiplicity of desired particle material(s), structure, size range, and functionality, many approaches exist for generating such particles. Bottom-up methods such as chemical synthesis have a high yield and work with a wide range of materials; however, these processes typically lead to large polydispersity and cannot produce structured particles. Top-down approaches such as microfluidics overcome the polydispersity issue and may produce a few different structures in particles, but at lower rates and only at the micro-scale. A method that can …

Self-Heating Control Of Edge Emitting And Vertical Cavity Surface Emitting Lasers, Yu Zhang

Electronic Theses and Dissertations

Self-heating leads to temperature rise of laser diode and limits the output power, efficiency and modulation bandwidth due to increased loss and decreased differential gain. The main heat sources in laser diode during continuous wave operation are Joule heating and free carrier absorption loss. To control device self-heating, the epi structure needs to be designed with low electrical resistance and low absorption loss, while the heat flux must spread out of the device efficiently. This dissertation presents the control of self-heating of both edge emitting laser diodes and vertical cavity surface emitting lasers (VCSELs). For the 980nm high power edge …