Optics Commons^™

Multi-Gaussian Random Variables For Modeling Optical Phenomena, Olga Korotkova, Milo W. Hyde Iv

Faculty Publications

A generalization of the classic Gaussian random variable to the family of multi-Gaussian (MG) random variables characterized by shape parameter M > 0, in addition to the mean and the standard deviation, is introduced. The probability density function (PDF) of the MG family members is an alternating series of Gaussian functions with suitably chosen heights and widths. In particular, for integer values of M, the series has a finite number of terms and leads to flattened profiles, while reducing to the classic Gaussian PDF for M = 1. For non-integer, positive values of M, a convergent infinite series of …

Wavelength And Power Dependence On Multilevel Behavior Of Phase Change Materials, Gary A. Sevison, Joshua A. Burrow, Haiyun Guo, Andrew M. Sarangan, Joshua R. Hendrickson, Imad Agha

Electro-Optics and Photonics Faculty Publications

We experimentally probe the multilevel response of GeTe, Ge2Sb2Te5 (GST), and 4% tungsten-doped GST (W-GST) phase change materials (PCMs) using two wavelengths of light: 1550 nm, which is useful for telecom-applications, and near-infrared 780 nm, which is a standard wavelength for many experiments in atomic and molecular physics. We find that the materials behave differently with the excitation at the different wavelengths and identify useful applications for each material and wavelength. We discuss thickness variation in the thin films used as well and comment on the interaction of the interface between the material and the substrate with regard to the …

Hyperpolarizability Dispersion Measured For Carbon Disulfide Vapor, Rodrigo N. Fernandez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The second hyperpolarizability (γ) of carbon disulfide (CS2) was measured by gas phase electric-field-induced second harmonic generation (ESHG), for laser wavelengths in the range of 765-1064 nm. The observed hyperpolarizability is decomposed into electronic (γ^e) and vibrational (γ^v) contributions, and the dispersion curve for γ^eis extrapolated to the static limit, with the result γ^e_0 = 12558 ± 93 atomic units. The results of this experiment agree with other recent nonlinear optical measurements and theoretical calculations.

Zernike Integrated Partial Phase Error Reduction Algorithm, Stephen C. Cain

Faculty Publications

A modification to the error reduction algorithm is reported in this paper for determining the prescription of an imaging system in terms of Zernike polynomials. The technique estimates the Zernike coefficients of the optical prescription as part of a modified Gerchberg-Saxton iteration combined with a new gradient-based phase unwrapping algorithm. Zernike coefficients are updated gradually as the error reduction algorithm converges by recovering the partial pupil phase that differed from the last known pupil phase estimate. In this way the wrapped phase emerging during each iteration of the error reduction algorithm does not represent the entire wrapped phase of the …

Beam Formation And Vernier Steering Off Of A Rough Surface, Eric K. Nagamine, Kenneth W. Burgi, Samuel D. Butler

Faculty Publications

Wavefront shaping can refocus light after it reflects from an optically rough surface. One proposed use case of this effect is in indirect imaging; if any rough surface could be turned into an illumination source, objects out of the direct line of sight could be illuminated. In this paper, we demonstrate the superior performance of a genetic algorithm compared to other iterative feedback-based wavefront shaping algorithms in achieving reflective inverse diffusion for a focal plane system. Next, the ability to control the pointing direction of the refocused beam with high precision over a narrow angular range is demonstrated, though the …

Advancement In Infrared Optics Through The Exploration Of Solution Derived Arsenic Selenide (As2se3) Thin Films, Annabella Orsini

Physics and Astronomy Summer Fellows

There are great opportunities for advancement in the realm of infrared (IR) optics through the use of chalcogenide glasses (ChGs). The development of IR optics using ChGs is important for applications in search and rescue operations, firefighting efforts, medical imaging, and satellites. Instead of creating bulky, expensive, single crystal IR glasses, ChGs can be deposited as thin films by solution derived (SD) spin or dip coating. Our research takes a multidisciplinary approach to investigate ChGs thin films using physics, chemistry, optics, and materials science.

Study Of The Effects Of Cavity Mode Spacing On Mode-Hopping In Iii–V/Si Hybrid Photonic Crystal Lasers, Praveen K.J. Singaravelu, Sharon M. Butler, Robert N. Sheehan, Alexandros A. Liles, Stephen P. Hegarty, Liam O'Faolain

Cappa Publications

We present a design methodology for hybrid lasers to realise mode-hop free operation by controlling the cavity mode spacing. In this study, a compact hybrid photonic crystal laser (H-PhCL) was employed which allowed a reduction of the Fabry–Perot length of the laser cavity and eliminated the need for an active mode stabilisation mechanism in order to realise mode-hop free operation. The H-PhCL was formed by butt-coupling a reflective semiconductor optical amplifier (RSOA) with a two-dimensional silicon (Si) photonic crystal (PhC) cavity. Continuous stable single frequency operation with >40 dB side-mode suppression ratio (SMSR) of the laser was achieved for gain …

Fundamental Aspects Of The Interaction Between Light And Nanostructures, Stephen Keith Sanders

Physics & Astronomy ETDs

Recent breakthroughs in nanophotonics have brought new opportunities to control and manipulate light at the nanoscale. The optical properties of metallic nanostructures have attracted particular interest because of their plasmon resonances, which couple strongly with visible light, and generate large near-field enhancements in their vicinity. In the first part of this thesis, we investigate the fundamental limits of the local density of photonic states near nanostructures by analyzing a sum rule relating its spectral integral to the field induced by a static dipole. Next, we analyze how the design of metallic nanoantennas can benefit from incorporating active materials that display …

Simulation Of Light Propagation Captured By Photoemission Electron Microscopy (Peem), Nabila Islam

Dissertations and Theses

The Photoemission electron microscopes (PEEM) is a powerful tool capable of synchronously imaging wave nature of light manifested by interference patterns as well as its particle nature through the energy exchange between the incident photons and the photoemitted imaging electrons. PEEM offers a non-invasive high-resolution approach for studying light propagation and interaction phenomena within a nanophotonic waveguide [7,8]. The electric field intensity variation of the interference pattern yielded by the interaction between the incident light and the guided mode coupled into the waveguide produces varying photoemission yields creating contrast in PEEM image. The guided modes cannot be excited simply by …

Optical Switching Performance Of Thermally Oxidized Vanadium Dioxide With An Integrated Thin Film Heater, Andrew M. Sarangan, Gamini Ariyawansa, Ilya Vitebskiy, Igor Anisimov

Electro-Optics and Photonics Faculty Publications

Optical switching performance of vanadium dioxide produced by thermal oxidation of vanadium is presented in this paper. A 100nm thick vanadium was oxidized under controlled conditions in a quartz tube furnace to produce approximately 200nm thick VO2. The substrate was appropriately coated on the front and back side to reduce reflection in the cold state, and an integrated thin film heater was fabricated to allow in-situ thermal cycling. Electrical measurements show a greater than three orders of magnitude change in resistivity during the phase transition. Optical measurements exhibit 70% transparency at 1500nm and about 15dB extinction across a wide spectral …

Computational Modeling Of Black Phosphorus Terahertz Photoconductive Antennas Using Comsol Multiphysics With Experimental Comparison Against A Commercial Lt-Gaas Emitter, Jose Isaac Santos Batista

Graduate Theses and Dissertations

This thesis presents computational models of terahertz (THz) photoconductive antenna (PCA) emitter using COMSOL Multiphysics commercial package. A comparison of the computer simulated radiated THz signal against that of an experimentally measured signal of commercial reference LT-GaAs emitter is presented. The two-dimensional model (2D) aimed at calculating the photoconductivity of a black phosphorus (BP) PCA at two laser wavelengths of 780 nm and 1560 nm. The 2D model was applied to the BP PCA emitter and the LT-GaAs devices to compare their simulated performance in terms of the photocurrent and radiated THz signal pulse. The results showed better performance of …

Fabrication And Characterization Of Photodetector Devices Based On Nanostructured Materials: Graphene And Colloidal Nanocrystals, Wafaa Gebril

Graduate Theses and Dissertations

Photodetectors are devices that capture light signals and convert them into electrical signals. High performance photodetectors are in demand in a variety of applications, such as optical communication, security, and environmental monitoring. Among many appealing nanomaterials for novel photodetection devices, graphene and semiconductor colloidal nanocrystals are promising candidates because of their desirable and unique properties compared to conventional materials.

Photodetector devices based on different types of nanostructured materials including graphene and colloidal nanocrystals were investigated. First, graphene layers were mechanically exfoliated and characterized for device fabrication. Self-powered few layers graphene phototransistors were studied. At zero drain voltage bias and room …

Estimating Turbulence Distribution Over A Heterogeneous Path Using Time‐Lapse Imagery From Dual Cameras, Benjamin Wilson, Santasri Bose-Pillai, Jack E. Mccrae, Kevin J. Keefer, Steven T. Fiorino

Faculty Publications

Knowledge of turbulence distribution along an experimental path can help in effective turbulence compensation and mitigation. Although scintillometers are traditionally used to measure the strength of turbulence, they provide a path-integrated measurement and have limited operational ranges. A technique to profile turbulence using time-lapse imagery of a distant target from spatially separated cameras is presented here. The method uses the turbulence induced differential motion between pairs of point features on a target, sensed at a single camera and between cameras to extract turbulence distribution along the path. The method is successfully demonstrated on a 511 m almost horizontal path going …

Examining Melt Pond Dynamics And Light Availability In The Arctic Ocean Via High Resolution Satellite Imagery, Austin Wesley Abbott

OES Theses and Dissertations

As the Arctic experiences consequences of climate change, a shift from thicker, multi-year ice to thinner, first-year ice has been observed. First-year ice is prone to extensive pools of meltwater (“melt ponds”) forming on its surface, which enhance light transmission to the ocean. Changes in the timing and distribution of melt pond formation and associated increases in under-ice light availability are the primary drivers for seasonal progression of water column primary production and warming. Observations of melt pond development and distribution require meter scale resolution and have traditionally been limited to airborne images. However, recent advances in high spatial resolution …

Distributed Feedback Master Oscillator Power Amplifier Using Interface Polaritons, Dongwon Jang

Graduate Theses - Physics and Optical Engineering

Characterization and simulation of an innovative solid-state distributed feedback master oscillator power amplifier (solid-state DFB MOPA) are presented, using interface polaritons (IPs) that enhance wave propagations at gain-loss interfaces in active layers. The author set up the design of the fabricated device, and a company, Freedom photonics, collaborated with us, allowing me to modify some of their designed MOPA systems. The master oscillator (MO) consists of a patterned grating on a waveguiding region to transfer only a single mode of 1.550 μm wavelength. The power amplifier (PA) is fabricated with the MO to reduce power loss and tapered to amplify …

On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid

Theses and Dissertations

In this thesis work, techniques for downsizing Optical modulators to nanoscale for the purpose of utilization in on chip communication and sensing applications are explored. Nanoscale optical interconnects can solve the electronics speed limiting transmission lines, in addition to decrease the electronic chips heat dissipation. A major obstacle in the path of achieving this goal is to build optical modulators, which transforms data from the electrical form to the optical form, in a size comparable to the size of the electronics components, while also having low insertion loss, high extinction ratio and bandwidth. Also, lap-on-chip applications used for fast diagnostics, …

Physically Based Rendering Techniques To Visualize Thin-Film Smoothed Particle Hydrodynamics Fluid Simulations, Aditya H. Prasad

Dartmouth College Undergraduate Theses

This thesis introduces a methodology and workflow I developed to visualize smoothed hydrodynamic particle based simulations for the research paper ’Thin-Film Smoothed Particle Hydrodynamics Fluid’ (2021), that I co-authored. I introduce a physically based rendering model which allows point cloud simulation data representing thin film fluids and bubbles to be rendered in a photorealistic manner. This includes simulating the optic phenomenon of thin-film interference and rendering the resulting iridescent patterns. The key to the model lies in the implementation of a physically based surface shader that accounts for the interference of infinitely many internally reflected rays in its bidirectional surface …

Assembly And Detection Of 3-D Qr Codes Through Additive Manufacturing And Terahertz Imaging, Patrick Dunn

Theses

Automatic identification and data capture, or AIDC, plays a substantial role in contemporary business, advertising, and military needs. The purpose of this study is to generate a potential alternative to current AIDC approaches by constructing three-dimensional plastic tags (or ‘3D QR codes’) using additive manufacturing techniques and interrogate them using Terahertz radiation. 3D Quick Response (QR) codes are designed in 3D computer-aided design software. The QR codes are 3D structures embedded in the printed plastic in which an air gap in the plastic (or an air gap filled in with another type of plastic) indicates a bit of information. Information …

Temperature-Sensitive Holograms With Switchable Memory, Muhammad Irfan Dr, Suzanne Martin Dr, Izabela Naydenova Prof

Articles

Abstract

Herein, the dynamics and reversibility of temperature-induced changes in volume phase holographic gratings (VPHGs) recorded in the low-toxicity self-processing photopolymer poly(N-isopropyl acrylamide) (poly-NIPA) are reported on. Transmission and reflection gratings are exposed to temperatures ranging 8–60 °C to study the effect of temperature on their properties. First, the role of the photopolymer chemical composition is investigated by comparing layers containing NIPA with those containing acrylamide (AA) and measuring the normalized diffraction efficiency (DE) at 60 °C; higher thermal sensitivity is observed for poly-NIPA gratings (24% drop) versus low sensitivity for AA gratings (2% increase). The impact of …

Optimization And Characterization Of Doped Optical Fibers For Radiation Balanced Fiber Laser And Amplifier, Mostafa Peysokhan

Optical Science and Engineering ETDs

Due to the reliability, compactness, low maintenance costs, superior performance, and versatility of fiber lasers and amplifiers, they are commonly employed in scientific and directed energy applications. Among all kinds of fiber lasers and amplifiers, high-power, Yb-dopped fiber lasers and amplifiers have been extensively researched to achieve higher output powers. One of the major hindrances to achieving higher powers with adequate stability and efficiency in high power performance is heat generated in the fiber lasers and amplifiers' core. The Radiation Balanced Laser (RBL) is a viable technique for heat mitigation has been proposed by S.~Bowman in 1995. RBL technique is …