Because xerogels may sustain both pressure and shear waves, several bands with negative index can be tailored. This property is very helpful in designing optical lenses as it allows to calculate the bend angle of beam of light when passes. The index of refraction provides a measure of the speed of an em wave as it propagates within a material. Materials that exhibit negative index ni of refraction have several potential applications in microwave technology. Specifically, it is shown that arrays of single and paired nanorods can provide such negative refraction. In the interest of completeness, cases of both positive and negative refraction are examined, with the host transmission line medium in place. Density effects on the negative refractive index of a split. 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. Introduction n the late 1960s, veselago proposed that materials with simultaneously negative permittivity and permeability are physically permissible and possess a negative index of refraction 1. Composites with negative refractive index, thermal, self. Negative refractive index in lefthanded materials david r. Lhms have attracted tremendous attention because of their potential applications to build the perfect lens and cloaking devices. If metamaterial is having permittivity and permeability near zero it is called zero index material. Eleftheriades, dispersion analysis of a microstripbased negative refractive index periodic structure, ieee microwave.
As it can be seen in the figure, the resonance is leftshifted by varying the gap d between the centers of the continuous wire. As a result of the negative index of refraction and negative phase velocity. In addition to a negative index ni of refraction, properties such as. Metamaterial structure based on split ring resonators srr is proposed in order to produce a negative refractive index.
However, the meta materials presented in 3 and 4 are bulky 3d constructions, which are difficult to adapt for rfmicrowave device and circuit applications. However, artificially designed materials metamaterials can act as nims. Th e refractive index is one of the most fundamental characteristics of light propagation in materials. For pairs of metal rods, a negative refractive index has been observed at 1. Left handed materials lhms are artificial materials that have negative electrical permittivity, negative magnetic permeability, and negative index of refraction across a common frequency band. Optical metamagnetism and negativeindex metamaterials. Pdf available in journal of computational and theoretical nanoscience 32. Negative refractive index how is negative refractive index. The group refractive indices of the metamaterial are shown to be 4. Physics of negative refractive index materials citeseerx.
The negative refractive index is obtained by a waveguide filled with a split ring resonator array in a frequency band below the cut off frequency of the waveguide. 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 the past few years, new developments in structured electromagnetic materials have given rise to negative refractive index materials which have both negative. Recently, some interest has shifted towards the realization of materials that exhibit zero or nearzero refractive index. Examples include enhanced transmission line capability, power enhancementsize reduction in antenna applications and, in the field of nondestructive testing, improved sensitivity of patch sensors and detection of subwavelength defects in dielectrics by utilizing a ni superlens. Since a metamaterial is a material which is having negative permittivity and permeability, it can be regarded as an artificial medium with negative index of refraction.
Ghost waves can be resonantly coupled to the incident evanescent waves, which then grow exponentially through the anisotropic media as in the case of negative index materials. In addition, the refractive index also provides a measure of the deflection of a beam of light as it crosses the interface between two materials having different values for their refractive indices. Negative refraction was determined by a snells law. Such an effect can be obtained using a metamaterial which has been designed to achieve a negative value for both electric permittivity. Physics and applications of negative refractive index materials. The first experimental realization of a negative refractive index in the optical range at 1. Indeed, it is now established that negative refraction can occur in materials displaying anisotropy, such as calcite, and in two or threedimensionally structured materials such as photonic crystals 11. Veselago4 suggested that there are materials in which the causal refractive index may be given by another branch of the root n. Negativerefractiveindex metamaterials using loaded. For this structure we have used a new approach, instead of applying light perpendicularly incident. We know that refractive index is square root of product of dielectric constant and magnetic permeability. We study the negative refractive index of a metamaterial as a function of the linear density of the lattice period at microwave frequency. My question is, if permittivity and permeabilitity of a material is negative then the end product, according to the above equation, should be positive. Negative refractive index metamaterials infrared nanooptics of.
Pdf negative refractive index materials researchgate. They possess electromagnetic em properties not found in nature. Index terms left handed materials, metamaterials, nanoparticle plasmon resonance, negative. A model of srr is used to understand the behavior and its affects. Pdf physics of negative refractive index materials semantic scholar. Negative refractive index metamaterials nrm are artificial composites, characteri zed by subwavelength features and negative effective value of re fractive index 2, 3. Metamaterials with negative refraction may lead to the development of a superlens capable of imaging objects and fi ne structures that are much smaller than the wavelength of light. Attention has been given to the fundamentals of negative index materials, the main design strategies and proposed applications which include subwavelength. To identify the signatures of negative refractionfrom a negative refractive index, valentine. The phase refractive index of the metamaterial remains positive, in contrast to that of lefthanded metamaterials 1,4. Negative refractive index in optics of metaldielectric.
Metamaterials showing negative refractive indexes, also called negativeindex materials nims, have also been demonstrated in the infrared range and at the border with the visible spectral range. The quantitative measure of this bending was provided by willebrord snell in 1621 18, 19, who showed that, 2 n 1 sin. Soukoulis1,3 1ames laboratory and department of physics and astronomy, iowa state university, ames, iowa 50011, usa 2institute of optical fiber commun. Negative refractive index metamaterials sciencedirect. A refractive index of zero implies that light enters a state of quasiinfinite phase velocity and infinite wavelength. Metamaterials showing negative refractive indexes, also called negative index materials nims, have also been demonstrated in the infrared range and at the border with the visible spectral range. Negative refractive index materials article pdf available in journal of computational and theoretical nanoscience 32. Note that the parallel component of wave vector is always preserved in transmission, but that energy flow is opposite to the wave vector.
For obtaining negative indices of refraction, microscopic inclusions in a host matrix material have been used anywhere from the photonic crystal regime all the way. Aug 11, 2008 metamaterials are artificially engineered structures that have properties, such as a negative refractive index 1,2,3,4, not attainable with naturally occurring materials. We present metamaterial as a lefthanded material which follows left hand rule. As ghost waves are supported by transparent dielectric media, they are free from the curse of material loss that is inherent to conventional negative index composites. Additionally, we report the results of a sample that displays nim behavior for red light at a wavelength of 710 nm and another sample that displays. Refractive index or the index of refraction is the ratio of the speed of light in vacuum or air to the speed of light in a transparent material. Negative refraction is a property of these artificial ma. It is clear that the negative refractive index for rcp and lcp originate from the chiral parameter. Planar negative refractive index media using periodically l c. Composites with negative refractive index 9 introduction we seek to develop structural composite materials with additional integrated functions. Emmms exhibit exotic properties not easily achieved using naturally occurring materials. Planar negative refractive index media using periodically l. Shalaev school of electrical and computer engineering, purdue university, 465 northwestern avenue, west.
Negative refractive index metamaterial structure using srr. So many exotic and remarkable electromagnetic phenomena have been predicted to occur in negativeindex materials, such as. 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. B 423 negative refractive index in optics of metaldielectric composites alexander v. Negative refractive index in artificial metamaterials. Optical metamagnetism and negativeindex metamaterials mrs. For normal incidence, the light intensity only decays. A reduction of negative refractive index appears when increasing the gap size. Negative refractive index metamaterials supporting 2d waves. If two negative numbers multiplied should give a positive number. Such properties include controlled electromagnetic, selfhealing, thermal management, and selfsensing properties that interact to create an innovative multifunctional material system. Examples include enhanced transmission line capability, power enhancementsize reduction in antenna applications and, in the field of nondestructive testing, improved sensitivity of patch sensors and detection of subwavelength defects in dielectrics by. These materials, referred to as lefthanded lhm or negative index materials, possess unique electromagnetic properties and promise novel optical devices, including a perfect lens. Planar negative refractive index media using periodically.
Consequences lefthanded or negative index of refraction metamaterials. Negative refractive index composite metamaterials for. Lhms have attracted tremendous attention because of their potential applications to build the perfect lens and. Negative refractive index transmission line structure, ieee trans. In recent years a very exciting and intense activity has been devoted to the understanding and construction of materials that enjoy exotic optical properties, such as a negative refractive index. Optical negative refraction in bulk metamaterials of nanowires. It also means that every point within the metamaterial. Threedimensional optical metamaterial with a negative. These have permitted emerging applications, concepts and devices to be developed in the last few years. 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. Negative index of refraction in optical metamaterials. Spherical silica xerogels are efficient acoustic mie resonators. Negative refractive index and acoustic superlens from. Physics of negative refraction and negative index materials.
However, the metamaterials presented in 3 and 4 are bulky 3d constructions, which are difficult to adapt for rfmicrowave device and circuit applications. Enhanced diffraction from a grating on the surface of a. Negative refractive index due to chirality jiangfeng zhou,1 jianfeng dong,2,1 bingnan wang,1 thomas koschny,1,3 maria kafesaki,3 and costas m. Specially designed metaldielectric composites can have a negative refractive index in the optical range. As light passes through the interface between two mediums of different refractive indices, it bends as shown in fig.