Showing papers by "John B. Pendry published in 2004"

Metamaterials and negative refractive index.

Abstract: Recently, artificially constructed metamaterials have become of considerable interest, because these materials can exhibit electromagnetic characteristics unlike those of any conventional materials. Artificial magnetism and negative refractive index are two specific types of behavior that have been demonstrated over the past few years, illustrating the new physics and new applications possible when we expand our view as to what constitutes a material. In this review, we describe recent advances in metamaterials research and discuss the potential that these materials may hold for realizing new and seemingly exotic electromagnetic phenomena.

Mimicking Surface Plasmons with Structured Surfaces

Abstract: Metals such as silver support surface plasmons: electromagnetic surface excitations localized near the surface that originate from the free electrons of the metal. Surface modes are also observed on highly conducting surfaces perforated by holes. We establish a close connection between the two, showing that electromagnetic waves in both materials are governed by an effective permittivity of the same plasma form. The size and spacing of holes can readily be controlled on all relevant length scales, which allows the creation of designer surface plasmons with almost arbitrary dispersion in frequency and in space, opening new vistas in surface plasmon optics.

A Chiral Route to Negative Refraction

Abstract: Negative refraction is currently achieved by driving the magnetic permeability and electrical permittivity simultaneously negative, thus requiring two separate resonances in the refracting material. The introduction of a single chiral resonance leads to negative refraction of one polarization, resulting in improved and simplified designs of negatively refracting materials and opening previously unknown avenues of investigation in this fast-growing subject.

Terahertz magnetic response from artificial materials.

Abstract: We show that magnetic response at terahertz frequencies can be achieved in a planar structure composed of nonmagnetic conductive resonant elements. The effect is realized over a large bandwidth and can be tuned throughout the terahertz frequency regime by scaling the dimensions of the structure. We suggest that artificial magnetic structures, or hybrid structures that combine natural and artificial magnetic materials, can play a key role in terahertz devices.

Reversing Light With Negative Refraction

Abstract: Materials engineered to have negative permittivity and permeability demonstrate exotic behavior, from a negative refractive index to subwavelength focusing.

Near-infrared photonic band gaps and nonlinear effects in negative magnetic metamaterials

Abstract: We describe and characterize a nanostructured metallic photonic crystal metamaterial which is magnetically active in the near-infrared region of the spectrum. The periodic array of modified split-ring resonator structures is numerically demonstrated to have a negative effective permeability at telecommunications wavelengths. Local electric fields in the structure can be many orders of magnitude larger than in free space thus allowing for enhanced nonlinear effects. We have derived an expression for the change in the resonance frequency of the structure due to the Kerr nonlinear index change and estimate a characteristic magnetic field strength for the observation of bistable behavior.

Spherical perfect lens: Solutions of Maxwell's equations for spherical geometry

Abstract: It has been recently proved that a slab of negative refractive index material acts as a perfect lens in that it makes accessible the subwavelength image information contained in the evanescent modes of a source. Here we elaborate on perfect lens solutions to spherical shells of negative refractive material where magnification of the near-field images becomes possible. The negative refractive materials then need to be spatially dispersive with $\ensuremath{\varepsilon}(r)\ensuremath{\sim}1/r$ and $\ensuremath{\mu}(r)\ensuremath{\sim}1/r.$ We concentrate on lenslike solutions for the extreme near-field limit. Then the conditions for the TM and TE polarized modes become independent of $\ensuremath{\mu}$ and $\ensuremath{\varepsilon},$ respectively.

Reversing Light: Negative Refraction

Abstract: ictor Veselago, in a paper 1 published in 1967, pondered the consequences for electromagnetic waves interacting with a hypothetical material for which both the electric permittivity, e , and the magnetic permeability, µ, were simultaneously negative. As no naturally occurring material or compound has ever been demonstrated with negative e and µ, Veselago wondered whether this apparent asymmetry in material properties was just happenstance, or perhaps had a more fundamental origin. Veselago concluded that not only should such materials be possible but, if ever found, would exhibit remarkable properties unlike those of any known materials, giving a twist to virtually all electromagnetic phenomena. So why are there no materials with negative e and µ? We first need to understand what it means to have a negative e or µ, and how it occurs in materials. The Drude-Lorentz model of a material is a good starting point, as it conceptually replaces the atoms and molecules of a real material by a set of harmonically bound electron oscillators, resonant at some frequency 0 ω . At

Manipulating the near field with metamaterials

Abstract: New technology is enabling scientists to engineer a class of electromagnetic materials on a scale of much less than a wavelength. The new materials have properties not seen in nature - such as a negative refractive index - which are the key to controlling the near field.

Existence and properties of microwave surface plasmons at the interface between a right-handed and a left-handed media

Abstract: Surface plasmons, (SPs) are interface waves very similar to Zenneck waves but existing only at optical frequencies where metals exhibit a negative permittivity. The availability of novel structured metamaterials with tailorable positive/negative constitutive parameters allows the generation of SPs in the microwave range, which may lead to novel components and antennas applications. This paper describes SPs existing at the interface between right-handed (RH) and left-handed (LH) materials. The dispersion relation is established, the properties of these SPs are discussed, a transmission line (TL) LC implementation of the RH/LH interface is proposed, and the phenomena are demonstrated by full-wave simulation in an effective medium approach.

Novel optical phenomena with photonic crystals

Abstract: In this work we present an introduction to photonic crystals by discussing the basic concepts and principles behind these artificial materials, as well as their abilities to control light and enable unusual optical phenomena. We will focus on specific examples including (1) negative refraction of light, (2) the superprism effect (anomalous electromagnetic dispersion), and (3) the possibility of superlensing (subwavelength focusing). These are very general results based on direct solutions of Maxwell’s equations, and can consequently be of relevance to many areas of science and technology.

'Short stories on line sources in meta-materials'

Abstract: Negative refractive index materials [1] have excited the optics community both through the intriguing possibilities they appear to offer, and the challenges they present to our understanding of the diffraction process. Most intriguing of all is the possibility of a lens whose resolution is limited not by wavelength, but only by the losses in the constituent materials. The resolution of this lens increases without limit as the losses tend to zero. However the lens is only one member of a whole category of systems, such as intersecting planes, which satisfy a generalized lens theorem [5]. We shall see that good use of coordinate transformations tackles geometries related to one another by mirror symmetry. In this pamphlet, we explore imaging effects through negative refraction in 1D Photonic Crystals. The tool of choice will be the generalised transfer matrix formalism. Our approach amounts to solving the Maxwell system by taking full account of the invariance of the structure in, say, x and y (using a Fourier Transform), and its periodicity in z (by means of Floquet-Bloch decomposition). We only assume that the electromagnetic field satisfies a prerequisite energy criterion of square integrability. We achieve a clean mathematical derivation which leads to an analytical expression for the field by means of the transfer matrix formalism which proved to be a fast and accurate algorithm in numerous studies on Photonic Band Gap structures through the past decade. Our meta-material requires of course some modifications with respect to the original algorithm (described for instance at length in [3,6,7]): we need now consider some loss in the layers with negative refractive index (for causality reasons). Further, we also introduce a periodic arrangement of line current sources oriented along the y -axis, which radiate in the overall periodic structure (see figure 1(a)).

Materials engineered to have negative permittivity and permeability demonstrate exotic behavior, from a negative refractive index to subwavelength focusing.

Abstract: 1published in 1968, pondered the consequences for electromagnetic waves interacting with a hypothetical material for which both the electric permittivity e and the magnetic permeability m were simultaneously negative. Because no naturally occurring material or compound has ever been demonstrated with negative e and m, Veselago wondered whether this apparent asymmetry in material properties was just happenstance or perhaps had a more fundamental origin. He concluded that not only should such materials be possible, but if ever found, they would exhibit remarkable properties unlike those of any known materials and would give a twist to virtually all electromagnetic phenomena. Foremost among these properties is a negative index of refraction.