Explaining negative refraction without negative refractive indices. At 738 nm, the fom is expected to become macroscopically large, of. Kildishev school of electrical and computer engineering, purdue university, west lafayette, in 47907 an array of pairs of parallel gold nanorods is shown to have a negative refractive index. To be specific, let us consider an optical medium in which the electric response is. Recently negative index materials nims and photonic crystals pcs are getting more and more attention because of its extraordinary optical properties like near. At a wavelength of 737 nm, the negative refractive index improves from. Artificial magnetism and negative refractive index are two specific types of behavior that have been demonstrated over the past few years, illustrating the new physics and new applications possible. With these properties, metamaterials have a negative refractive index due to which they produce negative refraction making them good candidates to. This demonstration of a previously unexploited electromagnetic em property proved the importance of engineered materials and has resulted in an extraordinary amount of continued development by scientists working in optics, electromagnetism, physics.
Negative refraction and negative refractive index in an optical uniaxial absorbent medium. Near field imaging with silver superlens near field imaging with magnetic metamaterials. Metamaterials metamaterials are artificial materials engineered to have properties that may not be found in nature. Negative and anomalous refraction in metamaterials and photonic.
Negativerefractiveindex metamaterials using loaded. A slab of the negative refractive index metamaterial has a focal length that can be tuned by changing the gradient of the negative refractive index. Negativeindex metamaterial or negativeindex material nim is a metamaterial whose refractive index for an electromagnetic wave has a negative value over. A negative refractive index, a property that does not exist in natural materials, can be produced in socalled metamaterials by combining two building blocks. In 2000, an artificially structured composite was shown to exhibit a negative index of refraction over a band of microwave frequencies 1. Determining the effective electromagnetic properties of. The refractive index is retrieved from direct phase and amplitude measurements for transmission and reflection, which are all in. Negative refractive index metamaterials sciencedirect. As your familiar with the definition of refractive index, it is the ratio of velocity of light in vacuum that velocity of light in the given medium. Download limit exceeded you have exceeded your daily download allowance. However, artificially designed materials metamaterials can act as nims. The theory underpinning this field treats electromagnetic composites using homogenization and effective medium theory emt.
Negative index of refraction in optical metamaterials. Osa metamaterials with gradient negative index of refraction. But this definition is not gonna answer your question. The refractive index in veselago materials is negative implying that the phase of a wave decreases rather than advances along propagation through these media leading to important implications for nearly all electromagnetic phenomena as pointed out by veselago himself. Negative effective refractive index the complex refractive index of a given medium is defined as the ratio between the speed of an electromagnetic wave through that medium and that in vacuum and can thus be written as n2. Negative refractive index transmission line structure, ieee trans. Metamaterials with nearzero refractive index designed using fishnet structures are proposed. The thickness of the three layers of au, al 2o 3, and au are 30, 75, and 30 nm. Such behavior results from the plasmon resonance in the pairs of nanorods for both the electric and the magnetic components of light. Negative refractive index in artificial metamaterials. Jun 20, 2016 metamaterials have earned their name with extraordinary properties such as negative refractive index and invisibility cloaking. Metamaterials with negative permeability and negative refractive index. The application of negative refractive index metamaterials to mm and submm wavelength instrumentation a thesis submitted to the university of manchester for the degree of doctor of philosophy in the faculty of engineering and physical sciences 20 imran mohamed school of physics and astronomy.
The application of negative refractive index metamaterials to. Negative refractive index and acoustic superlens from. Negative refractive index metamaterials nrm are artificial composites, characteri zed by subwavelength features and negative effective value of re fractive index 2, 3. Both the permittivity and the permeability are controlled via geometrical. Note that the parallel component of wave vector is always preserved in transmission, but that energy flow is opposite to the wave vector. In conclusion, for an array of pairs of parallel gold rods, we obtained a negative refractive index of n. In the interest of completeness, cases of both positive and negative refraction are examined, with the host transmission line medium in place. Basics of single negative and double negative metamaterials. Negative refraction through a triangular prism may be explained without assigning a negative refractive index to the prism by using array theory. The transmittance and the position of the kinks also increase with the same ordering of te a,te b,tm b, and tm a because better imfig.
A doubleperiodic array of pairs of parallel gold nanorods is shown to have a negative refractive index in the optical range. This thesis discusses negative index metamaterials nims that exhibit negative refraction. As a result, bringing the refractive index into a new domain of negative values has truly excited the imagination of researchers worldwide. Negative index materials nims have a negative refractive index so that electromagnetic waves in such media propagate in a direction opposite to the flow of energy, which is indeed unusual and counterintuitive. Th e notion of a negative refractive index is one such case. The greatest potential of metamaterials is the possibility to create a structure with a negative refractive index, since this property is not found in any nonsynthetic material. Jiangfeng zhou,1 thomas koschny,1,2 maria kafesaki,2 and costas m. Negative refractive index metamaterials infrared nanooptics of.
Characterization and applications of negativeindex metamaterials koray ayd. In addition to a negative index ni of refraction, properties such as artificial magnetism2, negative permittivity, and negative permeability have been observed in. Metamaterials with nearzero refractive index produced using. This new class of negativeindex materials is relatively easy to fabricate on the nanoscale and. Optical negative index metamaterials by xuhuai zhang. Index terms left handed materials, metamaterials, nanoparticle plasmon resonance, negative refractive index. Determining the effective electromagnetic properties of negativerefractiveindex metamaterials from internal. It is clear that the negative refractive index for rcp and lcp originate from the chiral parameter. Cummer department of electrical and computer engineering, duke university, durham, north carolina 27708, usa received 10 november 2004. Electromagnetic field in materials with negative refractive index 2004 4. The nearzero index band is generated with the overlap of electric and magnetic resonances, where the transition from a negative n region to a positiven region is found. Th is is because the index of refraction enters into the basic formulae for optics.
Negativerefractiveindex transmissionline metamaterials. Soukoulis1,2 1ames laboratory and department of physics and astronomy,iowa state university, ames, iowa 50011. Negative refraction and negative refractive index in an. Contents definition of single negative and double negative media properties and resulting applications common.
Negative index of refraction in optical metamaterials purdue. Chapter 1 negative refractive index metamaterials in optics. Negative refractive index response of weakly and strongly. Negative index metamaterial or negative index material nim is a metamaterial whose refractive index for an electromagnetic wave has a negative value over some frequency range. Refraction at an interface is commonly described by n the refractive index and we can show that causality forces us to choose a negative sign for the refractive index when both h and p are negative. A thin metal film pierced with holes of appropriate size or spacing between them can be used as a. H2 7 this expression is positive for a very broad class of dispersion equations for. Negative refraction is the name for an electromagnetic phenomenon where light rays are refracted at an interface in the reverse sense to that normally expected. Recently, artificially constructed metamaterials have become of considerable interest, because these materials can exhibit electromagnetic characteristics unlike those of any conventional materials. Negative refractive index response of weakly and strongly coupled optical metamaterials. Metamaterials and negative refractive index science. Such an effect can be obtained using a metamaterial which has been designed to achieve a negative value for both electric permittivity.
Electromagnetic field in materials with negative refractive index. Osa negative index of refraction in optical metamaterials. Ekmel ozbay june, 2008 metamaterials offer novel electromagnetic properties and promising applications including negative refraction, flatlenses, superlenses, cloaking devices. When frequency dispersion exists, the energy wmust be written in a different manner. Negative refractive index metamaterials supporting 2d waves. Negative index of refraction in optical metamaterials v. Negative refractive index in chiral metamaterials shuang zhang,1 yongshik park,1 jensen li,1 xinchao lu,2 weili zhang,2 and xiang zhang1,3, 1nanoscale science and engineering center, university of california, 5 etcheverry hall, berkeley, california 947201740, usa. Obviously, the causal refractive index 1, 2 should be used to characterise lhm. Eleftheriades, dispersion analysis of a microstripbased negative refractive index periodic structure, ieee microwave. Then the complex refractive index for the nim thin film sandwiched between the air and glass can be found from kildishev, cai, chettiar, yuan, sarychev, drachev and shalaev 2006 2. Negative refractive index in lefthanded materials david r.
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