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Twisted Moire Photonic Crystals: Their Nano-Fabrications, Optical Properties, and Applications in Light Extraction

Description: In this dissertation, I report the results of my research on twisted moiré photonic crystals which can be formed through multi-beam holographic interference without a physical rotation and later fabricated by electron-beam lithography. Their optical properties, such as photonic bandgaps, multiple resonance modes, and quality factor are presented. Randomized moire photonic crystals in lattice are also studied. The applications of moire photonic crystals in improving light extraction efficiency … more
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Date: May 2023
Creator: Alnasser, Khadijah Saleh T.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Developing Ultra-Fast Plasmonic Spiking Neuron via Integrated Photonics

Description: This research provides a proof of concept and background theory for the physics behind the state-of-the-art ultra-fast plasmonic spiking neurons (PSN), which can serve as a primary synaptic device for developing a platform for fast neural computing. Such a plasmonic-powered computing system allows localized AI with ultra-fast operation speed. The designed architecture for a plasmonic spiking neuron (PSN) presented in this thesis is a photonic integrated nanodevice consisting of two electro-opti… more
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Date: August 2022
Creator: Goudarzi, Abbas, Sr.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Manipulation of Light-Matter Interactions in Molybdenum Disulfide (MoS2) Monolayer through Dressed Phonons (DP) and Plasmons

Description: The performance of electrical and optical devices based on two-dimensional semiconductors (2D) such as molybdenum disulfide is critically influenced due to very poor light absorption in the atomically thin layers. In this study, the phonon mediated optical absorption and emission properties in single atomic layers of MoS2 have been investigated. The electronic transitions in MoS2 due to near-field optical interaction and the influence of interface phonons due to the dielectric substrate GaN on … more
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Date: December 2019
Creator: Poudel, Yuba R
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Tuning Effect on Thermal Radiative Emission of Thermo-Mechano-Optical Gratings and Multilayers

Description: The recipes of optical radiative properties manipulation are their materials chemistry, nano/microscale geometry, and transport properties of quasiparticle carriers such as photons, phonons, and electrons. The important technical element in optical properties is the dielectric function of materials, which is different for metals, dielectrics, 2D materials, and phase transition materials. Graphene has a unique electrical conductivity profile which have metallic nature depending on the frequency,… more
Date: December 2022
Creator: Araki, Ken
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Electrically Tunable Absorption and Perfect Absorption Using Aluminum-Doped Zinc Oxide and Graphene Sandwiched in Oxides

Description: Understanding the fundamental physics in light absorption and perfect light absorption is vital for device applications in detector, sensor, solar energy harvesting and imaging. In this research study, a large area fabrication of Al-doped ZnO/Al2O3/graphene/Al2O3/gold/silicon device was enabled by a spin-processable hydrophilic mono-layer graphene oxide. In contrast to the optical properties of noble metals, which cannot be tuned or changed, the permittivity of transparent metal oxides, such a… more
Date: December 2018
Creator: Adewole, Murthada Oladele
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Dynamic Screening via Intense Laser Radiation and Its Effects on Bulk and Surface Plasma Dispersion Relations

Description: Recent experimentation with excitation of surface plasmons on a gold film in the Kretschmann configuration have shown what appears to be a superconductive effect. Researchers claimed to see the existence of electron pairing during scattering as well as magnetic field repulsion while twisting the polarization of the laser. In an attempt to explain this, they pointed to a combination of electron-electron scattering in external fields as well as dynamic screening via intense laser radiation. Th… more
Date: August 2017
Creator: Lanier, Steven t
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Quantum Coherence Effects Coupled via Plasmons

Description: This thesis is an attempt at studying quantum coherence effects coupled via plasmons. After introducing the quantum coherence in atomic systems in Chapter 1, we utilize it in Chapter 2 to demonstrate a new technique of detection of motion of single atoms or irons inside an optical cavity. By taking into account the interaction of coherences with surface plasmonic waves excited in metal nanoparticles, we provide a theoretical model along with experimental data in Chapter 3 to describe the modifi… more
Date: December 2018
Creator: Moazzezi, Mojtaba
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Gradient-Index Metamaterial Infrared Detector for Enhanced Photo-Response and Image Quality

Description: An enhanced thermal imaging concept made possible through the development of a gradient-indexed metamaterial infrared detector that offers broadband transmission and reflection in THz waves. This thesis proposes a proof of feasibility for a metamaterial infrared detector containing an anti-reflective coating with various geometrically varying periodic metasurfaces, a gradient-indexed dielectric multilayer for near-perfect longpass filtering, and a gradient index of refraction (GRIN) metalens fo… more
Date: May 2022
Creator: Adams, Kelsa Derek
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Enhancement of Light Emission from Metal Nanoparticles Embedded Graphene Oxide

Description: A fully oxidized state of graphene behaves as a pure insulating while a pristine graphene behaves as a pure conducting. The in-between oxide state in graphene which is the controlled state of oxide behaves as a semiconducting. This is the key condition for tuning optical band gap for the better light emitting property. The controlling method of oxide in graphene structure is known as reduction which is the mixed state of sp2 and sp3 hybrid state in graphene structure. sp2 hybridized domains cor… more
Date: May 2016
Creator: Karna, Sanjay K.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Investigations of the Fresnel Lens Based Solar Concentrator System through a Unique Statistical-Algorithmic Approach

Description: This work investigates the Fresnel-lens-based solar concentrator-receiver system in a multi-perspective manner to design, test and fabricate this concentrator with high-efficiency photon and heat outputs and a minimized effect of chromatic aberrations. First, a MATLAB®-incorporated algorithm optimizes both the flat-spot and the curved lens designs via a statistical ray-tracing methodology of the incident light, considering all of its incidence parameters. The target is to maximize the solar ray… more
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Date: December 2019
Creator: Qandil, Hassan Darwish Hassan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties

Description: The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodific… more
Date: December 2017
Creator: De Silva, Vashista C
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Nanophotonics of Plasmonic and Two-Dimensional Metamaterials

Description: Various nanostructured materials display unique and interesting optical properties. Specific nanoscale objects discussed in an experimental perspective in this dissertation include optical metamaterials, surface plasmon sensors, and two-dimensional materials. These nanoscale objects were fabricated, investigated optically, and their applications are assessed. First, one-dimensional magnetic gratings were studied, followed by their two-dimensional analog, the so-called "fishnet." Both were fabri… more
Date: August 2018
Creator: Roccapriore, Kevin M
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Off-axis scattering of laser beams using single and multi-Gaussian phase function approximation

Description: Within the small-angle approximation, a multi-Gaussian phase function model provides a new description of the multiple scattering process and leads to improved agreement with experiment data. Future work will be concerned with the combination of small-angle and diffusion approximations in the radiative transfer. This should lead to an improved predictive model of the performance of electroopitcal systems in aerosol-loaded atmospheres. 10 refs., 3 figs.
Date: September 1, 1986
Creator: Zardecki, A. & Gerstl, S.A.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Analysis of the point-diffraction interferometer and application to testing of pressure-loaded windows

Description: A diffraction-theory analysis is given of the point-diffraction interferometer. The leading error present in the reference beam is expressed as a function of the pinhole diameter. A second part of the work presents a ray-tracing analysis of pressure-loaded windows; the leading-order distortion for incident plane waves is a weak lensing. The point-diffraction interferometer is used to confirm the analysis for an astigmatic aberration produced by cylindrical deformation of a plastic window.
Date: June 1, 1980
Creator: Riley, M. E. & Patterson, E. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Nonlinear optics: where do we go from here

Description: Nonlinear optics deals with induced polarizations which are not proportional to the input fields. This topic includes the spontaneous scattering of light waves by elementary excitations such as sound waves, plasma waves, heat waves, molecular vibrations (the Raman effect), spin waves, and a host of others; such spontaneous scatterings do not rely on the brightness of the probe light source, and therefore many of these topics were understood well before the invention of the laser. The laser did … more
Date: January 1, 1984
Creator: Fisher, R. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Aspects of Raman scattering and other effects on laser propagation through the atmosphere. Summary of work for the period, May 5, 1986-June 13, 1986

Description: The propagation of laser beams through the atmosphere is discussed. Processes which are pertinent are Raman scattering, self-focusing of beams, and two-photon absorption. Comments on the subroutine PRAMAN are given in the appendix. This subroutine calculates the effect of stimulated Raman scattering in the atmosphere. (WRF)
Date: August 1, 1986
Creator: Ipser, J.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fresnel diffraction in an optical system with focusing

Description: The migration of the axial intensity maximum from the geometrical focus toward the diffracting aperture, known as the focal shift, is explained in terms of the asymmetry of the Fresnel diffraction about focus. Conditions for the reversal or elimination of the focal shift are predicted. 8 refs.
Date: January 1, 1985
Creator: Wenzel, R.G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Whispering-mode waveguide

Description: Properties of a relatively new type of waveguide structure of potential use for confining infrared radiation to a small mode volume over long path lengths are reviewed. A single guiding surface with curvature radius rho and band radius R allows propagation of a near-grazing incidence whispering mode of transverse width approx.(lambda ..sqrt..rhoR/..pi..)/sup 1/2/ and radial width approx. 1/2 (lambda/sup 2/R)/sup 1/3. For sufficiently large rho, the loss per revolution for TE mode propagation is… more
Date: January 1, 1981
Creator: Kurnit, N.A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Geometry of wave electromagnetics

Description: A challenge to the commonly held view of light as a wave phenomenon is presented. An exact realization of light as generalized pencils or rays is constructed, with stress placed on using pencils of rays rather than single rays. Exact equations of motion are presented for the rays in the pencil, and these rays tend to travel in straight lines in empty space (not too near the edge of the beam). (GHT)
Date: October 27, 1980
Creator: Sudarshan, E. C.G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Spectral and parameter estimation problems arising in the metrology of high performance mirror surfaces

Description: The accurate characterization of mirror surfaces requires the estimation of two-dimensional distribution functions and power spectra from trend-contaminated profile measurements. The rationale behind this, and our measurement and processing procedures, are described. The distinction between profile and area spectra is indicated, and since measurements often suggest inverse-power-law forms, a discussion of classical and fractal models of processes leading to these forms is included. 9 refs.
Date: April 1, 1986
Creator: Church, E. L. & Takacs, P. Z.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Figure control for a segmented telescope mirror

Description: The properties of a system to control the figure of a large telescope primary mirror that is composed of many individual segments are studied. The geometry considered, employing hexagonal mirrors, allows a simple and economical control system. The system is shown to be reliable and effective in continuously maintaining the figure to the precision required for optical astronomy. 10 figures.
Date: March 1, 1979
Creator: Mast, T.S. & Nelson, J.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Imaging through a multiple scattering medium

Description: The existing theory of imaging through an aerosol medium, based on the small-angle approximation to radiative transfer, is extended to the general case of multiple scattering with an arbitrary degree of anisotropy. By applying the discrete-ordinates, finite-element radiation transport code TWOTRAN, we compute the modulation transfer function for a medium characterized by optical depth, single scattering albedo, and a symmetry parameter. An extended version of this investigation will appear in a… more
Date: January 1, 1984
Creator: Zardecki, A.; Gerstl, S.A.W. & Embury, J.F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Attempt to develop an ''intelligent'' lens design program

Description: We are developing a Lens Design Program intended to operate without user intervention, and to improve its performace with repeated usage. The methodology and current status will be discussed in this paper. 5 refs., 6 figs.
Date: January 1, 1985
Creator: Viswanathan, V. K.; Bohachevsky, I. O. & Cotter, T. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Extension of the method of the small angle approximation: open detector

Description: We use the radiative transfer equation to study the multiple scattering undergone by a laser beam propagating through a turbid medium. During the propagation, we view the beam as first scattering into a narrow forward cone, and then into a diffuse pattern. To describe this process, we propose a systematic and practical method to combine the small angle approximation with the diffusion approximation. The method works when the scattering cross-section describing scattering from aerosols can be wr… more
Date: August 18, 1986
Creator: Chitanvis, S.M. & Gerstl, S.A.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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