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1790 KiB

Open AccessArticle

Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in Dielectric Fluid

by Andrii B. Golovin, Jie Xiang, Heung-Shik Park, Luana Tortora, Yuriy A. Nastishin, Sergij V. Shiyanovskii and Oleg D. Lavrentovich

Materials 2011, 4(2), 390-416; https://doi.org/10.3390/ma4020390 - 14 Feb 2011

Cited by 20 | Viewed by 8927

Abstract

In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying [...] Read more.

In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying and switchable metamaterials that are based on colloidal dispersions of metal nano-rods (NRs) in dielectric fluids, in which dielectrophoretic forces, originating in the electric field gradients, create spatially varying configurations of aligned NRs. The electric field controls orientation and concentration of NRs and thus modulates the optical properties of the medium. Using gold (Au) NRs dispersed in toluene, we demonstrate electrically induced change in refractive index on the order of 0.1. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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792 KiB

Open AccessArticle

Emission Enhancement in a Plasmonic Waveguide at Cut-Off

by Andrea Alù and Nader Engheta

Materials 2011, 4(1), 141-152; https://doi.org/10.3390/ma4010141 - 04 Jan 2011

Cited by 13 | Viewed by 8330

Abstract

Enhancement of molecular emission is usually obtained by coupling small optical emitters with external resonant structures and systems, as first established by Purcell several decades ago, and verified in several recent investigations using molecules or quantum dots coupled with plasmonic nanoantennas. Here we [...] Read more.

Enhancement of molecular emission is usually obtained by coupling small optical emitters with external resonant structures and systems, as first established by Purcell several decades ago, and verified in several recent investigations using molecules or quantum dots coupled with plasmonic nanoantennas. Here we theoretically investigate in detail a different mechanism for emission enhancement, based on our recent idea of a plasmonic nanolauncher [Phys. Rev. Lett. 2009, 103, 043902], i.e., a metamaterial-inspired ultranarrow waveguide channel operating near its cut-off frequency. Such system is not necessarily at resonance, but its peculiar operation may provide enhanced emission over a relatively broad physical area, which may allow enhancement of emission independent of the position of an individual or of a group of molecules along such plasmonic channel, and the possibility to bend and route the emitted energy with large flexibility. We present here extensive theoretical and numerical results that confirm this intuition and may envision a novel method for molecular emission enhancement at the nanoscale, with more flexibility than the conventional Purcell resonance techniques. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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830 KiB

Open AccessArticle

Sub-Wavelength Resonances in Metamaterial-Based Multi-Cylinder Configurations

by Samel Arslanagić and Olav Breinbjerg

Materials 2011, 4(1), 117-130; https://doi.org/10.3390/ma4010117 - 31 Dec 2010

Cited by 2 | Viewed by 7348

Abstract

Sub-wavelength resonances known to exist in isolated metamaterial-based structures of circular cylindrical shape are investigated with the purpose of determining whether the individual resonances are retained when several of such resonant structures are grouped to form a new structure. To this end, structures [...] Read more.

Sub-wavelength resonances known to exist in isolated metamaterial-based structures of circular cylindrical shape are investigated with the purpose of determining whether the individual resonances are retained when several of such resonant structures are grouped to form a new structure. To this end, structures consisting of 1, 2 and 4 sets of metamaterial-based concentric cylinders excited by an electric line current are analyzed numerically. It is demonstrated that these structures recover the resonances of the individual structures even when the cylinders are closely spaced and the new structure is thus electrically small. The investigation is conducted through a detailed analysis of the electric near-field distribution as well as the radiation resistance in those cases where the individual structures are made of simple dielectric materials in conjunction with simple, but lossy and dispersive, metamaterials. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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1419 KiB

Open AccessArticle

Plasmonic Coaxial Waveguides with Complex Shapes of Cross-Sections

by Olga Kozina, Igor Nefedov, Leonid Melnikov and Antti Karilainen

Materials 2011, 4(1), 104-116; https://doi.org/10.3390/ma4010104 - 31 Dec 2010

Cited by 6 | Viewed by 9267

Abstract

In this paper, we describe waveguide properties of new optical waveguides made of noble metals and filled with glass and air. Such waveguides are coaxial cables and differ from a conventional coaxial in the shape of their central rods. Coaxial waveguide with annular [...] Read more.

In this paper, we describe waveguide properties of new optical waveguides made of noble metals and filled with glass and air. Such waveguides are coaxial cables and differ from a conventional coaxial in the shape of their central rods. Coaxial waveguide with annular and elliptic central rods are considered. Numerical simulations demonstrate that these waveguides, having nanosize cross-section, support propagation of few comparatively low-loss modes, having phase velocity close to the speed of light and the fields localized in a small area outside a metal. We illustrate excitation of these coaxial modes by dipole-like sources. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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673 KiB

Open AccessArticle

Active Microwave Metamaterials Incorporating Ideal Gain Devices

by Li-Ming Si, Tao Jiang, Kihun Chang, Te-Chuan Chen, Xin Lv, Lixin Ran and Hao Xin

Materials 2011, 4(1), 73-83; https://doi.org/10.3390/ma4010073 - 29 Dec 2010

Cited by 27 | Viewed by 9996

Abstract

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. [...] Read more.

Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL) incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept) while gain can be obtained (negative attenuation constant of transmission line) simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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374 KiB

Open AccessArticle

Fabrication of Large Area Fishnet Optical Metamaterial Structures Operational at Near-IR Wavelengths

by Neilanjan Dutta, Iftekhar O. Mirza, Shouyuan Shi and Dennis W. Prather

Materials 2010, 3(12), 5283-5292; https://doi.org/10.3390/ma3125283 - 15 Dec 2010

Cited by 13 | Viewed by 9177

Abstract

In this paper, we demonstrate a fabrication process for large area (2 mm × 2 mm) fishnet metamaterial structures for near IR wavelengths. This process involves: (a) defining a sacrificial Si template structure onto a quartz wafer using deep-UV lithography and a dry [...] Read more.

In this paper, we demonstrate a fabrication process for large area (2 mm × 2 mm) fishnet metamaterial structures for near IR wavelengths. This process involves: (a) defining a sacrificial Si template structure onto a quartz wafer using deep-UV lithography and a dry etching process (b) deposition of a stack of Au-SiO₂-Au layers and (c) a ‘lift-off’ process which removes the sacrificial template structure to yield the fishnet structure. The fabrication steps in this process are compatible with today’s CMOS technology making it eminently well suited for batch fabrication. Also, depending on area of the exposure mask available for patterning the template structure, this fabrication process can potentially lead to optical metamaterials spanning across wafer-size areas. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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Review

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1032 KiB

Open AccessReview

Negative Refractive Index Metasurfaces for Enhanced Biosensing

by Zoran Jakšić, Slobodan Vuković, Jovan Matovic and Dragan Tanasković

Materials 2011, 4(1), 1-36; https://doi.org/10.3390/ma4010001 - 23 Dec 2010

Cited by 85 | Viewed by 14805

Abstract

In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, [...] Read more.

In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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2055 KiB

Open AccessReview

Broadband Transformation Optics Devices

by Vera N. Smolyaninova, Igor I. Smolyaninov, Alexander V. Kildishev and Vladimir M. Shalaev

Materials 2010, 3(10), 4793-4810; https://doi.org/10.3390/ma3104793 - 21 Oct 2010

Cited by 7 | Viewed by 7966

Abstract

Recently we have suggested that two-dimensional broadband transformation optics devices based on metamaterial designs may be built using tapered waveguides. Here we review application of this principle to broadband electromagnetic cloaking, trapped rainbow, and novel microscopy devices. Full article

(This article belongs to the Special Issue Next Wave of Metamaterials)

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