Article

Superscattering of Light from Subwavelength Nanostructures

Ginzton Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
Physical Review Letters (Impact Factor: 7.51). 07/2010; 105(1):013901. DOI: 10.1103/PhysRevLett.105.013901
Source: PubMed

ABSTRACT

We provide a theoretical discussion of the scattering cross section of individual subwavelength structures. We show that, in principle, an arbitrarily large total cross section can be achieved, provided that one maximizes contributions from a sufficiently large number of channels. As a numerical demonstration, we present a subwavelength nanorod with a plasmonic-dielectric-plasmonic layer structure, where the scattering cross section far exceeds the single-channel limit, even in the presence of loss.

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Available from: Zhichao Ruan, Jul 28, 2015
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    • "The enhanced surface plasmon resonance in noble metallic systems at optical frequencies is expected to be a promising issue for realizing excellent scatterers and absorbers of the visible light5678. Recently, much attention has been paid to the light scattering from metal-dielectric layered structures, because of their promising applications in sensors[9], super-scattering[10]and invisible cloaking[11,12]. Surface plasmons are accompanied by localized enhancement of the electromagnetic field. "
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    ABSTRACT: Scattering of light by metal-coated dielectric nanocylinders periodically distributed along a cylindrical surface is investigated both theoretically and numerically. The structure is under the authors’ interest because of its practical application in design and fabrication of plasmonic devices such as plasmonic ring resonators, Plasmonic Crystals and THz waveguides. The method is based on the T-matrix approach and the field expansion into the cylindrical Floquet modes. The method is rigorous, straightforward and can be easily applied to various cylindrical configurations with different types and locations of the excitation sources. Scattering cross section and absorption cross section of three and four silver (Ag) coated-dielectric nanocylinders periodically situated along a cylindrical surface are studied. Near field distributions are investigated at particular wavelengths corresponding to the resonance wavelengths in the spectral responses. Special attention is paid to the unique and interesting phenomena characterizing the cylindrical structure composed of the metal-coated nanocylinders such as: a) localization of the field at the outer and inner interfaces of the metal-coated nanocylinders; b) excitement of the field in the gap region between the nanocylinders through the coupled plasmon resonance and c) strong confinement of the field inside the cylindrical structure. Detailed investigations have shown that unique phenomena characterizing the cylindrical configurations of the nanocylinders can be realized using a relatively simple structure composed of three nanocylinders and there is no need to further increase a number of the scatterers (nanocylinders). © 2016, Progress In Electromagnetics Research. All rights reserved.
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    • "One can also, according to Kirchoff's law, devise structures with tailored thermal emission characteristics at desired spectral range by optimizing the structures' light absorption properties [6] [13]. Besides absorption, it is also known that plasmonic nanostructures can serve as efficient antennas at optical frequencies, as evidenced by recent studies on optical Yagi-Uda antenna [14], superscatterers [15] and phasediscontinuous metamaterial surfaces [16]. "
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    ABSTRACT: We report fabrication and characterization of large-area ultrathin near-infrared light absorbers and scatterers based on a mono-layer of gold nanoparticles laying on top of a dielectric spacer and an aluminum reflector. The nanoparticles are formed through thermal annealing of an evaporated continuous gold film. Through optimization of initial gold-film thickness, spacer thickness, as well as annealing temperature we obtained samples that exhibit very low (~2%) broadband specular reflectance at near-infrared (NIR) wavelength range. By considering also diffuse reflection, we identify that the low specular reflectance can be due to either relatively high light absorption (~70%) or high light scattering (over 60%), with the latter achieved for samples having relatively sparse gold nanoparticles. Both strong absorption and scattering of NIR light are not inherent properties of the bulk materials used for fabricating the samples. Such composite optical surfaces can potentially be integrated to solar-energy harvesting and LED devices.
    Preview · Article · Jun 2015 · Journal of the European Optical Society Rapid Publications
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    • "Eq. (1) enables us to navigate between the two systems and relate their material parameters in a unique, systematic and rigorous way. Pendry et al. [1], Schurig et al. [15], and a number of other workers [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [16] [17] [18] have leveraged the fact that the medium parameters can be related via (1), in order to lay the foundations of designing cloaks, which render a target invisible when covered by using materials whose parameters are dictated by the TO. We will now explain the basic principles of TO-based cloaking, which, in principle, can render an object totally invisible . "
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    ABSTRACT: In this paper we present an alternative approach to addressing the problem of designing cloaks for radar targets, which have been dealt with in the past by using the transformation optics (TO) algorithm. The present design utilizes realistic materials, which can be fabricated in the laboratory, and are wideband as well as relatively insensitive to polarization and incident angle of the incoming wave. The design strategy, presented herein, circumvents the need to use metamaterials for cloak designs that are inherently narrowband, dispersive and highly sensitive to polarization and incident angle. A new interpretation of the TO algorithm is presented and is employed for the design of radar cross section-reducing absorbers for arbitrary targets, and not just for canonical shapes, e.g., cylinders. The topic of performance enhancement of the absorbers by using graphene materials and embedded frequency structure surfaces is briefly mentioned. The design procedure for planar absorbing covers is presented and their performance as wrappers of general objects is discussed. A number of test cases are included as examples to illustrate the application of the proposed design methodology, which is a modification of the classical TO paradigm.
    Preview · Article · Jun 2013
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