Query: Three-dimensional optical metamaterial with a negative refractive index

Candidate papers:

abstract: Metamaterials are artificially engineered structures that have properties, such as a negative refractive index, not attainable with naturally occurring materials. Negative index metamaterials (NIMs) were first demonstrated for microwave frequencies, but it has been challenging to design NIMs for optical frequencies and they have so far been limited to optically thin samples because of significant fabrication challenges and strong energy dissipation in metals. Such thin structures are analogous to a monolayer of atoms, making it difficult to assign bulk properties such as the index of refraction. Negative refraction of surface plasmons was recently demonstrated but was confined to a two dimensional waveguide. Three dimensional (3D) optical metamaterials have come into focus recently, including the realization of negative refraction by using layered semiconductor metamaterials and a 3D magnetic metamaterial in the infrared frequencies; however, neither of these had a negative index of refraction. Here we report a 3D optical metamaterial having negative refractive index with a very high figure of merit of 3.5 (that is, low loss) This metamaterial is made of cascaded 'fishnet' structures, with a negative index existing over a broad spectral range. Moreover, it can readily be probed from free space, making it functional for optical devices. We construct a prism made of this optical NIM to demonstrate negative refractive index at optical frequencies, resulting unambiguously from the negative phase evolution of the wave propagating inside the metamaterial. Bulk optical metamaterials open up prospects for studies of 3D optical effects and applications associated with NIMs and zero index materials such as reversed Doppler effect, superlenses, optical tunnelling devices, compact resonators and highly directional sources.
author_names: Jason G Valentine

Shuang Zhang

Thomas Zentgraf

Erick Ulin-Avila

Dentcho A Genov

Guy Bartal

Xunli Zhang
title: Three dimensional optical metamaterial with a negative refractive index
venue: Nature
year: 2008

abstract: Figure S1. The refractive index of the fishnet metamaterials for different numbers of layers and material loss. (a) The refractive index for different number of functional layers along the propagation direction. One important feature of metamaterials is the consistent refractive index profiles for different thicknesses. The effective refractive index was found by calculating the complex transmittance and reflectance and solving for the Fresnel equation:
author_names: Jason G Valentine

Shuang Zhang

Thomas Zentgraf

Erick Ulin-Avila

Dentcho A Genov

Guy Bartal

Xiang Zhang
title: Three Dimensional Optical Metamaterial Exhibiting Negative Refractive Index
year: 2008

abstract: We report experimental realization of the first three dimensional (3 D) optical negative index metamaterial. We measure the bulk refractive index using a 3 D prism and Snell's Law, unambiguously demonstrating negative phase propagation in the material.
author_names: Jason G Valentine

Shuang Zhang

Thomas Zentgraf

Erick Ulin-Avila

Dentcho A Genov

Guy Bartal

Xiang Zhang
title: Demonstration of Negative Refractive Index in a Three Dimensional Optical Metamaterial
year: 2008

abstract: As a consequent work of the two dimensional (2D) dendritic metamaterial which has been systematically studied in our previous work, a model of three dimensional (3D) sphere rod shaped structure is presented. Based on Drude model of the dielectric function of silver in the visible region, the parametric curves of electromagnetic response to the incident fields have been retrieved from detailed simulations. It is shown that the simultaneously negative values of permittivity and permeability in the optical range lead to a negative refractive index (NIM) through adjusting structural parameters, only the dimensions of the unit cells satisfy the effective medium theory. We therefore conclude that the proposed model offers a feasible route to fabricating 3D optical NIMs by 'bottom up' approach.
author_names: Boyi Gong

Xiaopeng Zhao
title: Numerical demonstration of a three dimensional negative index metamaterial at optical frequencies.
venue: Optics express
year: 2011

abstract: Materials showing electromagnetic properties that are not attainable in naturally occurring media, so called metamaterials, have been lately, and still are, among the most active topics in optical and materials physics and engineering. Among these properties, one of the most attractive ones is the subdiffraction resolving capability predicted for media having an index of refraction of 1. Here, we propose a fully three dimensional, isotropic metamaterial with strong electric and magnetic responses in the optical regime, based on spherical metallo dielectric core shell nanospheres. The magnetic response stems from the lowest, magnetic dipole resonance of the dielectric shell with a high refractive index, and can be tuned to coincide with the plasmon resonance of the metal core, responsible for the electric response. Since the response does not originate from coupling between structures, no particular periodic arrangement needs to be imposed. Moreover, due to the geometry of the constituents, the metamaterial is intrinsically isotropic and polarization independent. It could be realized with current fabrication techniques with materials such as silver (core) and silicon or germanium (shell) For these particular realistic designs, the metamaterials present a negative index in the range of 1.2 1.55mm. 3 Author to whom any correspondence should be addressed. New Journal of Physics 13 (2011) 123017 1367 2630/11/123017+15$33.00 (c) IOP Publishing Ltd and Deutsche Physikalische Gesellschaft
author_names: Javier Gil

Ricardo Marques Sillero

F Lopez Tejeira

Ramon Paniagua Dominguez
title: Metallo dielectric core shell nanospheres as building blocks for optical three dimensional isotropic negative index metamaterials
year: 2011

abstract: We study the propagation of light in a three dimensional double periodic Ag/TiO2 multilayer metamaterial composed of coupled plasmonic waveguides operating in the visible and UV spectral range. For these frequencies, light propagation in the plane of the waveguides is described by a negative phase velocity, while for the orthogonal direction light propagation is described by a Bloch wave composed of a large number of harmonics. As a result, the material cannot generally be described by a single phase index: decomposing the Bloch wave into different harmonics we show that for the wavelength range of interest the positive index m=1 harmonic dominates the propagation of light in the orthogonal direction. These results are corroborated by numerical simulations and optical refraction experiments on a double periodic Ag/TiO2 multilayer metamaterial prism in the 380 600 nm spectral range, which show that positive refraction associated with right handed harmonics dominates. Studying the isofrequency contours we find that despite the occurrence of multiple harmonics the double periodic structure can act as a flat lens: for a slab consisting of an integer number of unit cells all harmonics are degenerate and constructively interfere at the image plane. This work identifies important considerations relevant to the design of many three dimensional periodic metamaterials.
author_names: Ruben Maas

Ewold Verhagen

James Parsons

Albert Polman
title: Negative refractive index and higher order harmonics in layered metallodielectric optical metamaterials
year: 2014

abstract: A Luneburg lens is a fascinating gradient refractive index (GRIN) lens that can focus parallel light on a perfect point without aberration in geometrical optics. Constructing a three dimensional (3D) Luneburg lens at optical frequencies is a challenging task due to the difficulty of fabricating the desired GRIN materials. Here, we present the practical implementation of a 3D Luneburg lens at optical frequencies. Such a 3D Luneburg lens is designed with GRIN 3D simple cubic metamaterial structures, and fabricated with dielectric metamaterials by femtosecond laser direct writing in the commercial negative photoresist IP L. Simulated and experimental results exhibit an interesting 3D ideal focus for the infrared light. The protocol for developing the 3D Luneburg lens with ideal focus would prompt the potential applications in integrated light coupled devices and lab on chip integrated biological sensors based on infrared light.
author_names: Yuan Y Zhao

Yong-Liang Zhang

Mei-Ling Zheng

Xian-Zi Dong

Xuanming Duan

Zhen-sheng Zhao
title: Three dimensional Luneburg lens at optical frequencies
year: 2016

abstract: Abstract Metal dielectric metal films perforated with triangular nanoholes arranged in a hexagonal array are theoretically analyzed as metamaterial slabs. Effective constitutive parameters are calculated using three dimensional (3D) finite difference time domain (FDTD) simulations and S parameter retrieval method. Nanoholes side length and dielectric spacer thickness determine the magnitude and frequency of the hybridized plasmon modes resonances leading to negative effective permeability and plasmon modes inversion. Fundamental and second order asymmetric modes resonances lead to a double negative refractive index in the near infrared and a single negative refractive index in the visible range of the spectrum.
author_names: Mircea Giloan

Simion Astilean
title: Dual band optical negative index metamaterial based on hexagonal arrays of triangular nanoholes in metal dielectric films
year: 2013

abstract: Photonic metamaterials are man made structures composed of tailored micro or nanostructured metallodielectric subwavelength building blocks. This deceptively simple yet powerful concept allows the realization of many new and unusual optical properties, such as magnetism at optical frequencies, negative refractive index, large positive refractive index, zero reflection through impedance matching, perfect absorption, giant circular dichroism and enhanced nonlinear optical properties. Possible applications of metamaterials include ultrahigh resolution imaging systems, compact polarization optics and cloaking devices. This Review describes recent progress in the fabrication of three dimensional metamaterial structures and discusses some of the remaining challenges.
author_names: Costas M Soukoulis

Martin Wegener
title: Past achievements and future challenges in the development of three dimensional photonic metamaterials
year: 2011

abstract: Recently it has been predicted that materials with exceptionally strong optical activity may also possess a negative refractive index, allowing the realization of superlenses for super resolution imaging and data storage applications. Here we demonstrate experimentally and numerically that a chirality induced negative index of refraction is possible. A negative index of refraction due to three dimensional chirality is demonstrated for a bilayered metamaterial based on pairs of mutually twisted planar metal patterns in parallel planes, which also shows negative electric and magnetic responses and exceptionally strong optical activity and circular dichroism. Multilayered forms of the metamaterial are found to be suitable for use as ultrathin polarization rotators and circular polarizers for practical applications.
author_names: Eric Plum

Jiangfeng Zhou

Jian-feng Dong

Vassili A Fedotov

Thomas Koschny

Costas M Soukoulis

Nikolay I Zheludev
title: Metamaterial with negative index due to chirality
year: 2009