Metamaterials with ultralow index of refraction: properties and applications
10 Jul 2003-Vol. 5218, pp 166-172
TL;DR: In this paper, the effect of losses and dispersion on the effective refractive index of metal-dielectric nano-structures was analyzed in the visible range of frequencies considering the properties of real metals.
Abstract: There has been a growing interest in the design and fabrication of composite materials to enhance the flexibility in specifying their optical properties for device applications. Here we show that metamaterials composed of metal-dielectric nano-structures can be engineered to have an effective refractive index below unity at optical wavelengths. These materials show intriguing optical properties including total external reflection. Different rigorous and approximate modeling techniques will be compared. We will show a novel approach to derive a realistic value of the effective refractive index from the reflection coefficients of finite slabs. The effect of losses and dispersion will be analyzed in the visible range of frequencies considering the properties of real metals. We explain the differences among ultra-low refractive index metamaterials, photonic bandgap materials, and metals. Finally, we propose the application of these metamaterials to waveguide structures that guide light in air by total external reflection.
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TL;DR: In this paper, a new type of metallic structure has been developed that is characterized by having high surface impedance, which is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements and distributed in a two-dimensional lattice.
Abstract: A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.
4,264 citations
"Metamaterials with ultralow index o..." refers background in this paper
...surfaces.(11) In the visible regime, however, metal losses and dispersion become critical and cannot be neglected....
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TL;DR: In this paper, a photonic structure consisting of an extended 3D network of thin wires is shown to behave like a low density plasma of very heavy charged particles with a plasma frequency in the GHz range.
Abstract: A photonic structure consisting of an extended 3D network of thin wires is shown to behave like a low density plasma of very heavy charged particles with a plasma frequency in the GHz range. We show that the analogy with metallic behaviour in the visible is rather complete, and the picture is confirmed by three independent investigations: analytic theory, computer simulation and experiments on a model structure. The fact that the wires are thin is crucial to the validity of the picture. This new composite dielectric, which has the property of negative below the plasma frequency, opens new possibilities for GHz devices.
1,392 citations
TL;DR: In this article, the authors demonstrate that light propagation in strongly modulated two-dimensional (2D)/3D photonic crystals becomes refractionlike in the vicinity of the photonic bandgap.
Abstract: Although light propagation in weakly modulated photonic crystals is basically similar to propagation in a diffraction grating in which conventional refractive index loses its meaning, we demonstrate that light propagation in strongly modulated two-dimensional (2D)/3D photonic crystals becomes refractionlike in the vicinity of the photonic bandgap. Such a crystal behaves as a material having an effective refractive index controllable by the band structure. This situation is analogous to the effective-mass approximation in electron-band theory. By utilizing this phenomenon, negatively refractive material can be realized, which has interesting optical properties such as mirror-image refraction.
1,310 citations
"Metamaterials with ultralow index o..." refers background in this paper
...In principle, it is possible to assign them a refractive index less than unity and even less than zero that will be consistent with Snell’s law.(23) However, this is a different effect than TER from ULIMs because the photonic band gap materials do not (in principle) have the same angle-dependent reflectivity and transmissivity predicted by Fresnel formulae....
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TL;DR: It is shown that under proper conditions the energy radiated by a source embedded in a slab of metamaterial will be concentrated in a narrow cone in the surrounding media.
Abstract: In this paper we present the first results on emission in metamaterial. We show how the specific properties of metallic composite material can modify the emission of an embedded source. We show that under proper conditions the energy radiated by a source embedded in a slab of metamaterial will be concentrated in a narrow cone in the surrounding media. An experimental demonstration of this effect is given in the microwave domain, and the constructed antenna has a directivity equivalent to the best reported results with photonic-crystal-based antennas but using a completely different physical principle [B. Temelkuaran et al., J. Appl. Phys. 87, 603 (2000)].
1,158 citations
TL;DR: In this paper, the Clausius-Mossotti relation is made clearer by reversing the order, that is, by first obtaining the microscopic solution and then implementing the definition of macroscopic quantities as averages of their microscopic counterparts.
Abstract: Standard textbook derivations of the Clausius–Mossotti (Lorentz–Lorenz) relation tend to obscure the physical origin of local‐field effects by proceeding from the macroscopic dielectric function of the equivalent homogeneous system to the microscopic parameters of the model. The microscopic and macroscopic aspects can be made clearer by reversing the order, that is, by first obtaining the microscopic solution and then implementing the definition of macroscopic quantities as averages of their microscopic counterparts. This approach also leads naturally into a treatment of effective‐medium theory and the description of the dielectric response of heterogeneous materials.
695 citations