Showing papers by "John B. Pendry published in 2011"
TL;DR: The first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals is reported, capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres.
Abstract: Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices.
435 citations
01 Oct 2011
TL;DR: The basic concepts associated with transformation optics are reviewed and several examples to illustrate its application are provided, including the use of artificially structured metamaterials.
Abstract: Transformation optics is an emerging technique for the design of advanced electromagnetic media. Transformation optical devices exploit the form invariance of Maxwell's equations, allowing geometry to play the dominant role in the design process rather than traditional wave or ray optics. The use of coordinate transformations vastly eases the burden of design for a large class of devices, though at the expense of increasing the complexity of the underlying materials used. Although the required constitutive parameters of a transformation optical structure can be challenging-inherently anisotropic and spatially varying, with both magnetic and electric response-nevertheless the parameter requirements can often be met or approximated through the use of artificially structured metamaterials. Here, we review the basic concepts associated with transformation optics and provide several examples to illustrate its application.
118 citations
TL;DR: The absorption cross-section of a nanowire placed close to a metallic surface is derived within and beyond the quasi-static limit.
Abstract: The interaction between metallic nanowires and a metal substrate is investigated by means of transformation optics. This plasmonic system is of particular interest for single molecule detection or nanolasers. By mapping such a plasmonic device onto a metal-insulator-metal infinite structure, its optical response can be fully derived analytically. In this article, the absorption cross-section of a nanowire placed close to a metallic surface is derived within and beyond the quasi-static limit. The system is shown to support several modes characterized by a different angular momentum and whose resonance red-shifts when the nanoparticle approaches the metal substrate. These resonances give rise to a drastic field enhancement (>10(2)) within the narrow gap separating the nanoparticle from the metal surface. The case of a nanowire dimer is also investigated and is closely related to the previous configuration. More physical insights are provided especially with respect to the invisibility dips appearing in the radiative spectrum. Numerical simulations have also been performed to confirm our analytical predictions and determine their range of validity.
97 citations
TL;DR: The plasmonic interaction between overlapping nanowires with and without structure singularities is studied analytically and numerically and the band gap feature is shown to be robust to radiative losses and to the bluntness of the structure singularity.
Abstract: The plasmonic interaction between overlapping nanowires with and without structure singularities is studied analytically and numerically. A conformal transformation approach is adopted to predict analytically the optical response of overlapping nanowires in the quasi-static limit. Surface plasmon excitations are shown to exhibit a lower bound cutoff frequency, which blue-shifts when the overlap distance increases. Between this cutoff and the surface plasmon frequencies, overlapping nanowires are capable of a strong and broad-band harvesting of light. This band gap feature is shown to be robust to radiative losses and to the bluntness of the structure singularities. Hence, the light harvesting performance of overlapping nanowires would not be damaged by nanofabrication imperfections. These remarkable features might be beneficial to the realization of plasmonic band gap filters.
62 citations
TL;DR: In this article, the propagation of surface plasmons along rough metal surfaces with transformation optics is investigated with a cylindrical cavity and concave rough surface, and the effect of the contact angle between the asperities and the metal surface on the bandwidth and efficiency of the light harvesting process is analyzed.
Abstract: The propagation of surface plasmons along rough metal surfaces is investigated with transformation optics. The roughness is modeled on a nanometer scale either by partly embedding a cylinder of metal into the surface (convex rough surface) or by excavating a cylindrical cavity from it (concave rough surface). These two structures can be treated analytically by means of conformal transformation. The interaction of surface plasmons with the singularities of these structures is shown to induce extreme field enhancements. These modes dominate the surface-enhanced Raman-scattering response and enhancement factors of the order of ${10}^{7}$ are predicted. Interestingly, concave rough surfaces are shown to be the best candidates for surface-enhanced Raman scattering due to a stronger field enhancement and a lower sensitivity to the incident light polarization. Our analytical approach also points out the influence of the contact angle between the asperities and the metal surface on the bandwidth and the efficiency of the light-harvesting process.
51 citations
TL;DR: It is shown that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak nonadiabatic tuning of the wave velocity at time scales that can be much slower than the period.
Abstract: We show that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak nonadiabatic tuning of the wave velocity at time scales that can be much slower than the period. Unlike previous schemes, we demonstrate reversal of broadband (few cycle) pulses with simple structures. Our scheme may thus open the way to time reversal in a variety of systems for which it was not accessible before.
50 citations
TL;DR: This work discusses the merits of various TO strategies proposed for the long-sought ‘invisibility cloak’—a structure that renders opaque objects invisible and evaluates the cloaking capabilities of structures designed by the related CM approach, which makes use of conformal mapping to achieve index-only material distributions.
Abstract: We review several approaches to optical invisibility designed using transformation optics (TO) and optical conformal mapping (CM) techniques TO is a general framework for solving inverse scattering problems based on mimicking spatial coordinate transformations with distributions of material properties There are two essential steps in the design of TO media: first, a coordinate transformation that achieves some desired functionality, resulting in a continuous spatial distribution of constitutive parameters that are generally anisotropic; and, second, the reduction of the derived continuous constitutive parameters to a metamaterial that serves as a stepwise approximation We focus here on the first step, discussing the merits of various TO strategies proposed for the long-sought ‘invisibility cloak’—a structure that renders opaque objects invisible We also evaluate the cloaking capabilities of structures designed by the related CM approach, which makes use of conformal mapping to achieve index-only material distributions The performance of the various cloaks is evaluated and compared using a universal measure—the total (all-angle) scattering cross section
48 citations
Patent•
29 Dec 2011
TL;DR: In this paper, a control module is used to process current updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device.
Abstract: Exemplary embodiments enable an enhanced direct-viewing optical device to make customized adjustments that accommodate optical aberrations of a current user. In some instances a real-time adjustment of the transformable optical elements is based on known corrective optical parameters associated with a current user. In some implementations a control module may process currently updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device. Possible transformable optical elements include refractive and/or reflective and/or diffractive and/or transmissive characteristics that are adjusted based on current performance viewing factors for a given field of view of the direct-viewing device. Dynamic repositioning and/or transformation of corrective optical elements may be based on a detected shift of a tracked gaze direction of a current user of the direct-viewing device.
31 citations
TL;DR: The method described in this Letter is universal, in the sense that it can be applied to perfect lenses of any arbitrary geometry, and it is shown that the dynamics of perfect lensing is equivalent to the Dynamics of 2 coupled simple harmonic oscillators.
Abstract: This Letter is a theoretical attempt to answer two questions. First how long does it takes for perfect lensing to be observed, and second how does loss diminish the performance of a general perfect lens. The method described in this Letter is universal, in the sense that it can be applied to perfect lenses of any arbitrary geometry. We shall show that the dynamics of perfect lensing is equivalent to the dynamics of 2 coupled simple harmonic oscillators. Moreover we shall derive quantitatively, the effects of losses on a compact perfect lens.
26 citations
TL;DR: In this article, the wave front of short pulses can be accurately and efficiently reversed by use of simple one-dimensional zero-gap photonic crystals, and the analytical approach in detail, and discuss specific structures and modulation techniques as well as the required steps for achieving complete time reversal.
Abstract: Recently [Sivan and Pendry, Phys. Rev. Lett. 106, 193902 (2011)], we have shown that the wave front of short pulses can be accurately and efficiently reversed by use of simple one-dimensional zero-gap photonic crystals. In this paper, we describe the analytical approach in detail, and discuss specific structures and modulation techniques as well as the required steps for achieving complete time reversal. We also show that our scheme is only very weakly sensitive to material losses and dispersion.
24 citations
TL;DR: A Comment on the Letter by Mark I. Stockman, Phys.
Abstract: A Comment on the Letter by Mark I. Stockman, Phys. Rev. Lett. 106, 156802 (2011). The author of the Letter offers a Reply.
TL;DR: This work solves the associated wave equations analytically, and gives an explicit formula for the reversal efficiency, and discusses the implementation for short optical electromagnetic pulses and shows that the new scheme may lead to their accurate time-reversal with efficiency higher than before.
Abstract: Recently, Chumak et al. have demonstrated experimentally the time-reversal of microwave spin pulses based on non-adiabatically tuning the wave speed in a spatially-periodic manner [Nat. Comm. 1, 141 (2010)]. Here, we solve the associated wave equations analytically, and give an explicit formula for the reversal efficiency. We discuss the implementation for short optical electromagnetic pulses and show that the new scheme may lead to their accurate time-reversal with efficiency higher than before.
TL;DR: Manipulation of Maxwell's equation shows that metamaterials open the door to this new design paradigm for optics, providing the properties required to give complete control of light.
Patent•
29 Dec 2011
TL;DR: In this article, a control module is used to process current updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device.
Abstract: Exemplary methods, systems and components enable an enhanced direct-viewing optical device to make customized adjustments that accommodate various optical aberrations of a current user. In some instances a real-time adjustment of the transformable optical elements is based on known corrective optical parameters associated with a current user. In some implementations a control module may process currently updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device. Possible transformable optical elements may have refractive and/or reflective and/or diffractive and/or transmissive characteristics that are adjusted based on current performance viewing factors for a given field of view of the direct-viewing device. Some embodiments enable dynamic repositioning and/or transformation of corrective optical elements based on a detected shift of a tracked gaze direction of a current user of the direct-viewing device.
01 Jan 2011
TL;DR: Transformation optics is an emerging technique for the design of advanced electromagnetic media as mentioned in this paper, which exploits the form invariance of Maxwell's equations, allowing geometry to play the dominant role in the design process rather than traditional wave or ray optics.
Abstract: Transformation optics is an emerging technique for the design of advanced electromagnetic media. Transfor- mation optical devices exploit the form invariance of Maxwell's equations, allowing geometry to play the dominant role in the design process rather than traditional wave or ray optics. The use of coordinate transformations vastly eases the burden of design for a large class of devices, though at the expense of increasing the complexity of the underlying materials used. Although the required constitutive parameters of a transfor- mation optical structure can be challengingVinherently aniso- tropic and spatially varying, with both magnetic and electric responseVnevertheless the parameter requirements can often be met or approximated through the use of artificially struc- tured metamaterials. Here, we review the basic concepts asso- ciated with transformation optics and provide several examples to illustrate its application.
TL;DR: In this paper, a mathematical tool is used to predict what kind of metamaterial will bend light along a desired curved path, making devices such as invisibility cloaks possible.
Patent•
29 Dec 2011
TL;DR: In this paper, a control module is used to process current updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device.
Abstract: Exemplary methods, systems and components enable an enhanced direct-viewing optical device to make customized adjustments that accommodate various optical aberrations of a current user. In some instances a real-time adjustment of the transformable optical elements is based on known corrective optical parameters associated with a current user. In some implementations a control module may process currently updated wavefront measurements as a basis for determining appropriate real-time adjustment of the transformable optical elements to produce a specified change in optical wavefront at an exit pupil of the direct-viewing device. Possible transformable optical elements may have refractive and/or reflective and/or diffractive and/or transmissive characteristics that are adjusted based on current performance viewing factors for a given field of view of the direct-viewing device. Some embodiments enable dynamic repositioning and/or transformation of corrective optical elements based on a detected shift of a tracked gaze direction of a current user of the direct-viewing device.
TL;DR: In this article, the authors present a method to construct artificial structures with special properties, such as the reflecting metals we use in mirrors, from natural materials such as reflecting metals and reflectors.
TL;DR: In this paper, the authors proposed a new time-reversal scheme for optical pulses which overcomes the limitations of exisitng schems and demonstrated highly efficient and broadband reversal of pulses of 100 fs and 10 ps duration.
Abstract: We propose a new time-reversal scheme for optical pulses which overcomes the limitations of exisitng schems. We demonstrate highly efficient and broadband reversal of pulses of 100 fs and 10 ps duration.
01 Jan 2011
TL;DR: In this paper, the interaction of a dipole emitter with complex plasmonic nanostructures is investigated by means of transformation optics, and the fluorescence enhancement as well as the quantum efficiency are derived analytically.
Abstract: In this paper, the interaction of a dipole emitter (e.g molecule or quantum dot) with complex plasmonic nanostructures is investigated by means of transformation optics. The fluorescence enhancement as well as the quantum efficiency are derived analytically. Their spectral and spatial properties are analyzed in the perspective of future experiments.