DOCSLIB.ORG

Copyright by Matthew David Guild 2012 the Dissertation Committee for Matthew David Guild Certifies That This Is the Approved Version of the Following Dissertation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Copyright by Matthew David Guild 2012 the Dissertation Committee for Matthew David Guild Certifies That This Is the Approved Version of the Following Dissertation Copyright by Matthew David Guild 2012 The Dissertation Committee for Matthew David Guild certifies that this is the approved version of the following dissertation: Acoustic Cloaking of Spherical Objects Using Thin Elastic Coatings Committee: Andrea Al`u,Supervisor Michael R. Haberman, Supervisor Mark F. Hamilton Preston S. Wilson Loukas F. Kallivokas Acoustic Cloaking of Spherical Objects Using Thin Elastic Coatings by Matthew David Guild, B.S.; M.S.E. DISSERTATION Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY THE UNIVERSITY OF TEXAS AT AUSTIN May 2012 Dedicated to Melissa Acoustic Cloaking of Spherical Objects Using Thin Elastic Coatings Publication No. Matthew David Guild, Ph.D. The University of Texas at Austin, 2012 Supervisors: Andrea Al`u Michael R. Haberman In this thesis, a detailed description of acoustic cloaking is put forth using a coating consisting of discrete layers, enabling the cancellation of the scattered field around the object. This particular approach has previously only been applied to electromagnetic waves, for which it was observed that cloaking could be achieved using isotropic materials over a finite bandwidth. The analysis begins with a presen- tation of the theoretical formulation, which is developed using classical scattering theory for the scattered acoustic field of an isotropic sphere coated with multiple layers. Unlike previous works on acoustic scattering from spherical bodies, the cri- teria for acoustic cloaking is that the scattered field in the surrounding medium be equal to zero, and seeking a solution for the layer properties which achieve this condition. To effectively investigate this situation, approximate solutions are obtained by assuming either quasi-static limits or thin shells, which provide valuable insight into the fundamental nature of the scattering cancellation. In addition, using these approximate solutions as a guide, exact numerical solutions can be obtained, en- abling the full dynamics of the parameter space to be evaluated. Based on this v analysis, two distinct types of acoustic cloaking were found: a plasmonic cloak and an anti-resonance cloak. The plasmonic cloak is a non-resonant type of cloak, named plasmonic be- cause of its analogous behavior to the non-resonant cloak observed in electromag- netic waves which utilizes plasmonic materials to achieve the necessary properties. Due to the non-resonant behavior, this type of cloak offers the possibility of a much broader range of cloaking. To expand this design beyond wavelengths on the order of the uncloaked scatterer, multilayered cloak designs are investigated. The anti-resonance cloak, as the name suggests, uses the anti-resonances of the modes within the cloaking layer to supplement the non-resonant plasmonic cloaking of the scattered field. Although somewhat more limited in bandwidth due to the presence of anti-resonances (and the accompanying resonances), this type of cloak enables a larger reduction in the scattering strength, compared with using a single elastic layer utilizing only non-resonant cloaking. A thorough investigation of the design space for a single isotropic elastic cloaking layer is performed, and the necessary elastic properties are discussed. The work in this thesis describes the investigation of the theoretical for- mulation for acoustic cloaking, expanding upon the use of scattering cancellation previously developed for the cloaking of electromagnetic waves. This work includes a detailed look at the different physical phenomena, including both resonant and non-resonant mechanisms, that can be used to achieve the necessary scattering can- cellation and which can be applied to a wide range of scattering configurations for which cloaking would be desirable. In addition to laying out a broad theoretical foundation, the use of limiting cases and practical examples demonstrates the effec- tiveness and feasibility of such an approach to the acoustic cloaking of a spherical object. vi Table of Contents Abstract v List of Tables x List of Figures xi Chapter 1. Introduction 1 1.1 Thesis objectives . 1 1.2 Thesis overview . 3 Chapter 2. Background and fundamentals of acoustic cloaking 6 2.1 Transformation cloaks for acoustic waves . 7 2.1.1 Inertial cloak . 8 2.1.1.1 Basic formulation . 9 2.1.1.2 Use of acoustic metamaterials . 14 2.1.2 Pentamode materials and acoustic metafluids . 20 2.2 Anomalous resonance cloaking . 22 2.3 EM plasmonic cloaking . 24 2.3.1 Basic formulation . 25 2.3.2 Use of plasmonic materials . 28 2.3.3 Physical analogy between EM and acoustic waves . 30 Chapter 3. Theoretical formulation of acoustic scattering cancella- tion 33 3.1 Method of potentials . 34 3.2 Solution for scattering coefficients and scatter cancellation . 37 3.3 Relation to scattering cross-section . 41 3.4 Numerical implementation . 45 3.4.1 Minimization of scattered field . 45 3.4.2 Parameter space . 48 vii Chapter 4. Investigation of acoustic plasmonic cloaking using a single layer 50 4.1 Analytic expressions for a single fluid cloaking layer . 51 4.1.1 Low frequency approximation . 56 4.1.2 Thin shell approximation . 61 4.2 Cloaking of a rigid sphere . 65 4.3 Cloaking of a fluid sphere . 75 4.4 Cloaking of an isotropic elastic sphere . 80 4.5 Comparison with a single elastic cloaking layer . 89 Chapter 5. Investigation of acoustic anti-resonance cloaking 96 5.1 Formulation for a single elastic layer . 97 5.2 Anti-resonance cloaking of a rigid sphere . 102 5.2.1 Determining anti-resonance behavior . 102 5.2.2 Effects of elastic shear within the cloaking layer . 107 5.2.3 Limiting case of a fluid cloaking layer . 112 5.3 Anti-resonance cloaking of an elastic sphere . 112 5.4 Anti-resonance cloaking of a hollow sphere . 118 Chapter 6. Investigation of acoustic plasmonic cloaking using multi- ple layers 126 6.1 Exact analytic expressions . 126 6.2 Two fluid cloaking layers . 131 6.2.1 Region 1: ρc1 ρc2 . 135 6.2.2 Region 2: ρc1 ρc2 . 140 6.3 Cloaking of a rigid sphere using two fluid layers . 141 6.3.1 Region 1: ρc1 ρc2 . 142 6.3.2 Region 2: ρc1 ρc2 . 145 6.4 Elastic effects . 149 6.4.1 Penetrable elastic core . 149 6.4.2 Scattering strength reduction using two fluid layers . 151 6.4.3 Practical considerations for implementation . 154 6.5 Alternating fluid-fluid and fluid-elastic layers . 159 viii Chapter 7. Theoretical formulation for spherically isotropic elastic layers 166 7.1 Spherical isotropy . 168 7.2 Historical development of solution techniques . 172 7.3 State-space formulation . 174 7.4 Relation to the scattered field in an isotropic medium . 181 Chapter 8. Conclusions 191 8.1 General conclusions and contributions . 191 8.1.1 How the acoustic field scattered from a spherical object can be significantly reduced or cancelled . 191 8.1.2 How a realizable cloak is achieved . 192 8.2 Suggestions for future work . 196 Appendices 199 Appendix A. Linear system of equations derivation for scattering from isotropic sphere coated with isotropic shells 200 A.1 Basic formulation . 200 A.2 Solution for a single layer coated sphere . 201 A.3 Solution for an elastic sphere coated with two fluid layers . 205 A.4 Solution for a submerged sphere covered with a multilayer coating . 207 A.4.1 Surrounding fluid medium . 207 A.4.2 Multilayer coating . 207 A.4.3 Core material . 209 Appendix B. Derivation of expressions containing products of spher- ical Bessel functions of the first and second kind 211 Appendix C. Verification of results using COMSOL multiphysics 214 Index 217 Bibliography 219 ix List of Tables 4.1 Properties of elastic spheres to be cloaked for the three examples considered in this section. 80 4.2 Properties of single fluid layer plasmonic cloak of an elastic core for ka = 0:5, 0:75, and 1:00. 81 4.3 Properties of single fluid layer plasmonic cloak of a fluid core for ka = 0:5, 0:75, and 1:00. 82 5.1 Material properties of a single elastic cloaking layer designed at kd;0a= b 1:0 with =1:30 for a rigid, immovable sphere. 104 a 5.2 Material properties of a single elastic cloaking layer designed at kd;0a= b 1:0 with = 1:30 for a rigid, immovable sphere, based on the first a anti-resonance of the n=1 mode. 108 5.3 Material properties of spheres to be cloaked in Sections 5.3 and 5.4. 115 b 5.4 Properties of a single elastic cloaking layer with = 1:30 for the a different core materials examined in Sections 5.3 and 5.4. 116 6.1 Cloaking layer properties for a steel sphere in water, coated by an acoustic plasmonic cloak consisting of two layers with shell thicknesses δ1 =δ2 =0:04 and a design frequency of kd;0a=2:0. Solutions are given based on analytic thin-shell expressions, exact solutions for the case of two fluid layers, and exact solutions for the case of a fluid inner layer and isotropic elastic outer layer with νc1 =0:3. 152 6.2 Cloaking layer properties for a four layer acoustic plasmonic cloak for a steel sphere in water at a design frequency of kd;0a = 2:0. The shell thicknesses δ of the four layers, in order of the outermost to innermost layer, are 0:0135, 0:0642, 0:0037 and 0:0046, respectively. Exact solutions obtained numerically for the case of four fluid layers, and the case of alternating fluid and isotropic elastic layers with νc1 = 0:3...................................... 161 x List of Figures 2.1 Illustration of the coordinate transformation between an undeformed space (left) and a symmetric deformed space (right).
Load more

Recommended publications
  • Modeling of Metamaterials in Wave Propagation
    Modeling of Metamaterials in Wave Propagation G. Leugering, E. Rohan and F. Seifrt Lehrstuhl für Angewandte Mathematik II, Universität Erlangen-Nürnberg, Germany. New Technologies Research Center, Research Institute at University of West Bohemia, Plzen, Czech Re- public. Abstract: This chapter focuses on acoustic, electromagnetic, elastic and piezo-electric wave propagation through heterogenous layers. The motivation is provided by the demand for a better understanding of meta-materials and their possible construction. We stress the analo- gies between the mathematical treatment of phononic, photonic and elastic meta-materials. Moreover, we treat the cloaking problem in more detail from an analytical and simulation oriented point of view. The novelty in the approach presented here is with the interlinked homogenization- and optimization procedure. INTRODUCTION as ’negative Poisson’ ratio in elastic material foams, negative ’mass’ and ’negative refraction indices’ for The terminology ’metamaterials’ refers to ’beyond the forming of band-gaps in acoustic and optical de- conventional material properties’ and consequently vices, respectively. those ’materials’ typically are not found in nature. Thus given acoustic, elasto-dynamic, piezo-electric It comes as no surprise that research in this area, or electromagnetic wave propagation in a non- once the first examples became publicly known, has homogeneous medium and given a certain merit undergone an exponential growth. Metamaterials function describing the desired material-property or are most often man-made, are engineered materi- dynamic performance of the body involved, one als with a wide range of applications. Starting in wants to find e.g. the location, size, shape and the area of micro-waves where one aims at cloak- material properties of small inclusions such that ing objects from electromagnetic waves in the in- the merit function is increased towards an opti- visible frequency range, the ideas rather quickly in- mal material or performance.
    [Show full text]
  • Do Cloaked Objects Really Scatter Less?
    Do Cloaked Objects Really Scatter Less? Francesco Monticone and Andrea Alù* Department of Electrical and Computer Engineering, The University of Texas at Austin, 1 University Station C0803, Austin, Texas 78712, USA *[email protected] We discuss the global scattering response of invisibility cloaks over the entire frequency spectrum, from static to very high frequencies. Based on linearity, causality and energy conservation we show that the total extinction and scattering, integrated over all wavelengths, of any linear, passive, causal and non-diamagnetic cloak necessarily increases compared to the uncloaked case. In light of this general principle, we provide a quantitative measure to compare the global performance of different cloaking techniques and we discuss solutions to minimize the global scattering signature of an object using thin, superconducting shells. Our results provide important physical insights on how invisibility cloaks operate and affect the global scattering of an object, suggesting ways to defeat countermeasures aimed at detecting cloaked objects using short impinging pulses. I. INTRODUCTION The last decade has witnessed a significant progress in the field of classical electrodynamic theory and applications, following the introduction and development of the concept of metamaterials. This field of research has provided a new theoretical framework and practical tools to control electromagnetic waves and fields in unprecedented ways, beyond what is directly offered by natural materials [1]. Among a broad landscape of
    [Show full text]
  • Wsn 47(2) (2016) 75-88 Eissn 2392-2192
    Available online at www.worldscientificnews.com WSN 47(2) (2016) 75-88 EISSN 2392-2192 Acoustic cylindrical cloak S. M. Premarathna, K. A. I. L. Wijewardena Gamalath* Department of Physics, University of Colombo, Colombo 3, Sri Lanka *E-mail address: [email protected] ABSTRACT Using the analogy between anisotropic acoustic metamaterials with magnetic metamaterials in transverse magnetic mode, an electromagnetic wave of 2 GHz n transverse magnetic mode, at normal incidence propagating through a two dimensional, anisotropic, semi infinite, double negative, metamaterial slab of 800 × 800 cells, embedded in free space, for the ideal loss case was simulated by a radially dependent finite difference time dependent method to study an ideal acoustic cylindrical cloak. For the simulations multiple cycle m-n-m pulses generating Gaussian beams were used as sinusoidal hard line sources. The simulations for acoustic cylindrical cloaking by a reduced parameter model and a higher order parameter model are also presented. The cloaking behaviour is largely dependent upon the transformation and not on the thickness of the cloak. The radial dependent model and the higher order transformation model are suited for acoustic cloaking. Keywords: Acoustic metamaterials; electromagnetic metamaterials; negative index; anisotropic’ cloaking, radially dependent FDTD method; reduced parameter model’ higher order parameter model 1. INTRODUCTION The purpose of a cloaking device is to define a region of space invisibly isolated from passing acoustic waves. This is accomplished by manipulating the paths traversed by sound through a novel acoustic material. Although the objects in the defined location are still present, the incident waves are guided around them without being affected by the object itself.
    [Show full text]
  • Electromagnetic Description and Unexpected Effects
    Metamaterials and composites: electromagnetic description and unexpected effects IEEE AP-Society Distinguished Lecture Hong Kong Chapter — 2 March 2015 City University of Hong Kong Ari Sihvola Aalto University Department of Radio Science and Engineering Finland FINLAND ESPOO Annual Meeting of the American Physical Society 29 December 1959 There’s plenty of room at the bottom! Today’s keywords • scales & levels • geometry–matter interaction • emergence/enhancement of losses • effective description and complex constitutive relations • mixing rules METAMATERIALS ? METAMATERIALS ? Wikipedia definition (changing…) 2006: In electromagnetism (covering areas like optics and photonics), a meta material (or metamaterial) is an object that gains its (electromagnetic) material properties from its structure rather than inheriting them directly from the materials it is composed of. This term is particularly used when the resulting material has properties not found in naturally-formed substances. 2014: Metamaterials gain their properties not from their composition, but from their exactingly-designed structures. Their precise shape, geometry, size, orientation and arrangement can affect the waves of light or sound in an unconventional manner, creating material properties which are unachievable with conventional materials. A. Sihvola (2003): Electromagnetic emergence in metamaterials, in Advances in Electomagnetics of Complex Media and Metamaterials, (S. Zouhdi et al., eds), NATO Science Series, 89, 1-17. A. Sihvola (2007): Metamaterials in electromagnetics. Metamaterials, 1, 2-11. Scales in (electromagnetic) material modeling İ ȝ ȟ ȗ Collection of dipole and multipole moments Physical structure (meta)material levels and phenomena • materialization • mathematization • realization • idealization • synthetization • projection • localization • homogenization • fabrication • parametrization • modularization - non-unique - wash-out of microsopic structure - several realizations - loss of details - multiple platforms - emergence, paradigm change For example, in EE context..
    [Show full text]
  • Control of the Electromagnetic Fields by Metamaterials
    International Journal of Research Studies in Electrical and Electronics Engineering(IJRSEEE) Volume 4, Issue 1, 2018, PP 9-23 ISSN 2454-9436 (Online) DOI: http://dx.doi.org/10.20431/2454-9436.0401002 www.arcjournals.org Control of the Electromagnetic Fields by Metamaterials Tatjana Gric1, Aleksej Trofimov1 1Vilnius Gediminas Technical University *Corresponding Author: Dr. Tatjana Gric, Vilnius Gediminas Technical University, Lithuania. Abstract: Metamaterials are engineered composites. Much of the effort in the electrical engineering, material science, physics, and optics communities emphasized constructing efficient metamaterials and using them for potentially novel applications in antenna and radar design, subwavelength imaging, and invisibility cloak design. The purpose of this chapter is to provide a detailed introduction to the basic metamaterial modelling approaches and an overview of innovative phenomena enabled by metamaterials. While high tunability of the electromagnetic properties might be provided by metamaterial structures and metasurfaces, the former option has not yet been used to solve this problem. By means of the freedom of design provided by metamaterials, we propose the ways to redirect electromagnetic fields and demonstrate a design strategy. Keywords: Metamaterial, electromagnetic field, cloaking 1. INTRODUCTION Metamaterials are engineered composites [1-3]. Much of the effort in the electrical engineering, material science, physics, and optics communities emphasized constructing efficient metamaterials and using them for potentially novel applications in antenna and radar design, subwavelength imaging, and invisibility cloak design [4, 5]. The purpose of this chapter is to provide a detailed introduction to the basic metamaterial modelling approaches and an overview of innovative phenomena enabled by metamaterials. While high tunability of the electromagnetic properties might be provided by metamaterial structures and metasurfaces, the former option has not yet been used to solve this problem.
    [Show full text]
  • Metamaterial Advances for Radar and Communications
    METAMATERIAL ADVANCES FOR RADAR AND COMMUNICATIONS Dr. Eli Brookner Raytheon Company (retired); 282 Marrett Rd., Lexington, MA 02421 [email protected], Tel and Fax: +1-781-862-7014 Radar-2018, August, 27-30, 2018, Brisbane, Australia Keywords: Metamaterial, Radar, AESA, phased arrays, ESA, magnetic ground plane, magnetic dielectric, conformal For one form of metamaterial the permittivity (ε) and perme- antenna, cloaking, stealth, invisibility, WAIM, EBG, fractals. ability (μ) are both negative. When this happens the index of refraction n =√με is negative, the negative sign being used Abstract: for the square root [2, 3]. (Actual materials will have com- Metamaterial antennas have progressed considerably in plex-valued and µ. The real parts of both and µ do not have the last few years. Kymeta has made available its com- to be negative to display negative refraction [3].) Material mercial metamaterial electronically scanned antenna with negative n is rarely found in nature. (ESA) in 2018. It is intended for use on vessels anywhere in the world for high speed internet using satellites. Echo- However, it can be produced by forming an array of metal dyne and Metawave (formerly PARC, a Xerox Co.), have split-rings and rods (short parallel wires). The split-ring res- developed a metamaterial arrays for radar and cell onators produce a permeability μ that is negative while the phone usage. The Army Research Laboratory in Adelphi rods produce a permittivity ε that is negative. The dimensions MD has funded the development of a metamaterial 250- of the metallic rings and rods have to be smaller than the 505 MHZ antenna with a λ/20 thickness.
    [Show full text]
  • Graphene Based Metamaterials for Terahertz Cloaking and Subwavelength Imaging
    University of Mississippi eGrove Electronic Theses and Dissertations Graduate School 2015 Graphene Based Metamaterials For Terahertz Cloaking And Subwavelength Imaging Seyedali Forouzmand University of Mississippi Follow this and additional works at: https://egrove.olemiss.edu/etd Part of the Electromagnetics and Photonics Commons Recommended Citation Forouzmand, Seyedali, "Graphene Based Metamaterials For Terahertz Cloaking And Subwavelength Imaging" (2015). Electronic Theses and Dissertations. 531. https://egrove.olemiss.edu/etd/531 This Thesis is brought to you for free and open access by the Graduate School at eGrove. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of eGrove. For more information, please contact [email protected]. GRAPHENE BASED METAMATERIALS FOR TERAHERTZ CLOAKING AND SUBWAVELENGTH IMAGING A Thesis presented in partial fulfillment of requirements for the degree of Master of Science in the Department of Electrical Engineering with Emphasis in Electromagnetics The University of Mississippi by SEYEDALI FOROUZMAND August 2015 Copyright © 2015 by Seyedali Forouzmand All rights reserved. ABSTRACT Graphene is a two-dimensional carbon crystal that became one of the most controversial topics of research in the last few years. The intense interest in graphene stems from recent demonstrations of their potentially revolutionary electromagnetic applications – including negative refraction, subdiffraction imaging, and even invisibility – which have suggested a wide range
    [Show full text]
  • Research Thesis
    CZECH TECHNICAL UNIVERSITY IN PRAGUE Faculty of Nuclear Sciences and Physical Engineering Department of Physics Research thesis The cloaking effect in metamaterials from the point of view of anomalous localized resonance Bc. Filip Hlozekˇ Supervisor: Mgr. David Krejciˇ rˇ´ık, PhD., DSc. Prague, 2015 Title: The cloaking effect in metamaterials from the point of view of anomalous lo- calised resonance Author: Bc. Filip Hlozekˇ Specialization: Mathematical physics Sort of project: Research work Supervisor: Mgr. David Krejciˇ rˇ´ık, Ph.D., DSc. ————————————————————————————— Abstract: We summarize here some basic facts about history and manufacturing the first metamaterial. Some possible applications for metamaterials are men- tioned but the main concern of this work is on the metamaterial cloaking. We present some of the many theoretical approaches especially so called cloaking due to anomalous localized resonance (CALR). This concept is then used in this work. Inspired by work of Bouchitt and Schweizer in 2 dimensions calculation of the CALR for spherical symmetric setting dielectricum-metamaterial-dielectricum in 3 and higher dimensions is made . We prove here that CALR does not occur in such case. Key words: metamaterials, Maxwell’s equations, invisibility cloaking, anomalous localized resonance, localization index Nazev´ prace:´ Efekt neviditelnosti v metamaterialech´ z pohledu anomaln´ ´ı lokalisovane´ res- onance Autor: Bc. Filip Hlozekˇ Zameˇrenˇ ´ı: Matematicka´ fyzika Druh prace:´ Vyzkumn´ y´ ukol´ Skolitel:ˇ Mgr. David Krejciˇ rˇ´ık, Ph.D., DSc. ————————————————————————————— Abstrakt: Seznam´ ´ıme se zde strucnˇ eˇ s histori´ı a vyrobou´ prvn´ıch metamaterial´ u.˚ Zm´ın´ıme nekterˇ e´ moznˇ e´ aplikace, hlavn´ı pozornost je vsakˇ venovˇ ana´ maskovan´ ´ı pomoc´ı metamaterial´ u.˚ Predvedemeˇ nekterˇ e´ z mnoha teoretickych´ prˇ´ıstupu,˚ ktere´ se daj´ı pouzˇ´ıt k popisu neviditelnosti, zejmena´ se zameˇrˇ´ıme na maskovan´ ´ı po- moc´ı tzv.
    [Show full text]
  • Electromagnetic, Acoustic, and Thermal Invisibility School Tentative Program
    EUPROMETA – 27th Doctoral School on Metamaterials 4-8 May 2015 – Rome, Italy Electromagnetic, acoustic, and thermal invisibility School Tentative Program Program: 4 May – Monday Hour Topic Lecturer 09:30 – 10:00 Participant registration 10:00 – 10:15 Welcome and open 10:15 – 11:15 Metamaterial cloaking: theoretical aspects and limitations – Part I Prof. Andrea Alù 11:15 – 11:45 Break 11:45 – 12:45 Metamaterials cloaking: theoretical aspects and limitations – Part II Prof. Andrea Alù 12:45 – 14:30 Lunch 14:30 – 15:30 Electromagnetic cloaking and invisibility at microwave frequencies – Prof. S. Tretyakov Part I 15:30-16:00 Break 16:00-17:00 Electromagnetic cloaking and invisibility at microwave frequencies – Prof. S. Tretyakov Part II 17:00-19:00 Self-study 5 May – Tuesday Hour Topic Lecturer 09:30 – 10:30 Mantle cloaking and applications in antennas – Part I Profs. F. Bilotti and A. Toscano 10:30 – 11:00 Break 11:00-12:00 Mantle cloaking and applications in antennas – Part II Profs. F. Bilotti and A. Toscano 12:00-13:00 Assignments 14:30-15:30 Magnetostatic cloaking – Part I Prof. Àlvar Sanchez 15:30-16:00 Break 16:00-17:00 Magnetostatic cloaking – Part II Prof. Àlvar Sanchez 17:00-18:00 Is actually possible to make the velocity invisible? Prof. Davide Ramaccia 18:00-19:00 Exercises and self-study M. Barbuto, P. Gori, C. Guattari, A. Monti, D. Ramaccia 1 6 May – Wednesday Hour Topic Lecturer 09:30-10:30 Cloaking in optics: scientific background and experiments – Part I Prof. Martin Wegener 10:30-11:00 Break 11:00-12:00 Cloaking in optics: scientific background and experiments – Part II Prof.
    [Show full text]
  • Broadband Electromagnetic Cloaking with Smart Metamaterials
    ARTICLE Received 24 Jul 2012 | Accepted 23 Oct 2012 | Published 20 Nov 2012 DOI: 10.1038/ncomms2219 Broadband electromagnetic cloaking with smart metamaterials Dongheok Shin1, Yaroslav Urzhumov2, Youngjean Jung1, Gumin Kang1, Seunghwa Baek1, Minjung Choi1, Haesung Park1, Kyoungsik Kim1 & David R. Smith2 The ability to render objects invisible with a cloak that fits all objects and sizes is a long- standing goal for optical devices. Invisibility devices demonstrated so far typically comprise a rigid structure wrapped around an object to which it is fitted. Here we demonstrate smart metamaterial cloaking, wherein the metamaterial device not only transforms electromagnetic fields to make an object invisible, but also acquires its properties automatically from its own elastic deformation. The demonstrated device is a ground-plane microwave cloak composed of an elastic metamaterial with a broad operational band (10–12 GHz) and nearly lossless electromagnetic properties. The metamaterial is uniform, or perfectly periodic, in its unde- formed state and acquires the necessary gradient-index profile, mimicking a quasi-conformal transformation, naturally from a boundary load. This easy-to-fabricate hybrid elasto- electromagnetic metamaterial opens the door to implementations of a variety of transformation optics devices based on quasi-conformal maps. 1 School of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea. 2 Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA. Correspondence and requests for materials should be addressed to K.K. (email: [email protected]). NATURE COMMUNICATIONS | 3:1213 | DOI: 10.1038/ncomms2219 | www.nature.com/naturecommunications 1 & 2012 Macmillan Publishers Limited.
    [Show full text]
  • From Left Handed Materials to Invisible Cloak: Recent Advances
    From Left Handed Materials to Invisible Cloak: Recent Advances *Harihar Paudyala,d , Manoj Johrib,d and Akhilesh Tiwaric aDepartment of Physics, Birendra Multiple Campus, Tribhuvan University, Bharatpur, Chitwan, Nepal, b Department of Physics and Electronics, DA-V College, CSJM University, Kanpur 208 001, India cClermont Université, Université Blaise Pascal, Laboratoire de Génie Chimique et Biochimique (LGCB), BP 10488. F-63000, France dThe Abdus Salam International Centre for Theoretical Physics, Strada Costeria 11, Trieste, Italy. * [email protected] Abstract: Last decade has been increasing interest in metamaterial research, however metamaterials are sometimes regarded as left handed materials (LHM) or negative index materials but the recent progress in the field has shown that metamaterials are far beyond LHMs. In this paper we provide further advancement in the field of structured electromagnetic from LHM to invisible cloak. Keywords: cloaking, negative index meta-material, photonic crystal. 1. INTRODUCTION resonant elements, slow wave structure, super- The first known [1-3] metamaterials (MMs) i.e. directivity super resolution, sub-wavelength ruby glass with gold nano-particles embedded were focusing and imaging, inverse scattering, bi- used by artist and craftsmen for making art pieces anisotropy, photonic band gap material, waves on centuries ago. The Lycurgus cup exhibited in the nanoparticals were alive at the time of the upsurge British museum and the Roman glass challis are and could be regarded as various forerunners
    [Show full text]
  • A Review of Metamaterial Invisibility Cloaks
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NAL-IR A Review of Metamaterial Invisibility Cloaks Balamati Choudhury1 and R. M. Jha2 Abstract The exciting features of metamaterial in In aerospace applications, invisibility implies preventing conjunction with transformation optics leads to various information about an object from reaching radar-like applications in the microwave regime with such examples as detectors. This has been done by reducing the cross-section of invisible cloak, frequency selective surfaces (FSS), radomes, the object using various stealth techniques. The goal of etc. The concept of electromagnetic invisibility is very much cloaking phenomenon leads to the optimal version of stealth important in aerospace platform. Hence to study the feasibility technique, i.e. no reflection or absorption of energy. of implementation of this concept for stealth, an extensive A perfectly invisibility cloak has the scattering property of literature survey of metamaterial cloaks has been carried out vacuum. As stealth technology is an important part of and reported in this paper along with the basic concept of aerospace engineering, an initiative has been taken here to cloaking. To make the review more effective, the technical study the feasibility of metamaterial invisibility cloak towards papers are classified into three broad sections viz. stealth technology. An extensive literature survey of mathematical modeling, design and simulations, and metamaterial invisibility cloaks has been carried out and fabrications and experimental demonstration. Further the reported in this work. The methods implemented for analysis design and simulation is focused on different techniques of metamaterial cloaks with possibility of application to the implemented such as finite difference time domain (FDTD), specific frequency range have been reviewed.
    [Show full text]