Metamaterial

Metamaterial

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  Metamaterial Name: Nishargo Nigar(142000212)
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  What is aMetamaterial? This word is a combination of “meta” and “material”, Meta is a Greek word which means something beyond, altered, or changed. Metamaterials can have their electromagnetic properties altered to something beyond what can be found in nature.
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  Properties of Metamaterials All "natural" materials like glass, or diamond have positive electrical permittivity, magnetic permeability and an index of refraction. In these new artificially fabricated materials – called negative index materials (NIM) or double negative (ONG) media or left handed (LH) materials or backward wave (BW) media - all these material parameters are negative.  The electrical permittivity and the magnetic permeability are the main determinants of a material's response to electromagnetic (EM) waves. In metamaterials, both these material parameters are negative.  Correspondingly, the refractive index of the metamaterials is also negative.  Another strange property of metamaterials is its reverse Doppler effect.
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  Classification  Materials canbe classified on the basis of permittivity ε and permeability µ.  In figure-1, the first quadrant (ε >0, µ>0) represents right handed material (RHM).The forward Propagation of wave takes place in the first quadrant. It is commonly used material and follows the right hand thumb rule for direction of propagation of wave.  The second quadrant (ε< 0 and µ > 0) describes electric plasmas supporting evanescent waves, also called ENG (epsilon negative) material.  The fourth quadrant (ε> 0 and µ < 0) also supports evanescent, corresponding to MNG (µ negative material)
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  Classification  The thirdquadrant (ε<0, µ<0) represents Metamaterial, also called left handed material or double negative material(DNG).It follows the left handed rule because propagation of wave takes place in backward direction in this medium. Due to negative µ and negative ε the refractive index of the medium is calculated to be negative. Electric vector E, electromagnetic vector H and wave vector k forms the left hand triplet.
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  How Metamaterials Work Howto achieve negative index of refraction - - negative refraction can be achieved when both µr and εr are negative - negative µr and εr occur in nature, but not simultaneously -silver, gold, and aluminum display negative εr at optical frequencies -resonant ferromagnetic systems display negative µr at resonance -to appear homogeneous, the structures would have to be electrically small and spaced electrically close rrn    1))(())(( 2/2/2/1     jjjjj rr eeeee
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  Applications Metamaterial antenna Cloaking device Superlens Invisiblesubmarines Photonics OR opto-electronics Perfect absorber of light Metamaterials for solar cells
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  Metamaterial Antenna  Highgain, electrically configurable beam forming maximizes channel efficiency  Ultra-fast reconfiguration allows SDAs to realign on a frame-by-frame basis  Self-alignment eliminates the need for expensive technician installations or mechanical steering gimbals, as well as self-recovery from displacement  Active dynamic null generation allows mitigation of interfering signals when used in cluttered spectrum  Lightweight, compact and capable of being ruggedized for size-sensitive applications in harsh environments  Conformal form factor enables geometry-flexible antennas to be placed where conventional antennas could not be located  Support for a wide spectrum of frequencies across the RF, microwave, and millimeter wave spectrums
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  Cloaking Device  Thepurpose of a cloaking device is to hide something, so that a defined region of space is invisibly isolated from passing electromagnetic fields, as with Metamaterial cloaking.  The object doesn't really disappear; the vanishing is an illusion. With the same goal, researchers employ metamaterials to create directed blind spots by deflecting certain parts of the electromagnetic spectrum. It is the light spectrum, as the transmission medium, that determines what the human eye can see.  Light is refracted or reflected determining the view, color, or illusion that is seen. The visible extent of light is seen in a chromatic spectrum such as the rainbow. However, visible light is only part of a broad spectrum, which extends beyond the sense of sight.
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  Superlens  The imagingresolution of conventional lenses is limited by diffraction. Artificially engineered metamaterials now offer the possibility of building a superlens that overcomes this limit.  We review the physics of such superlenses and the theoretical and experimental progress in this rapidly developing field.  Superlenses have great potential in applications such as biomedical imaging, optical lithography and data storage.  A practical superlens, is a lens which uses metamaterials to go beyond the diffraction limit.
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  Invisible submarines  An’acoustic cloak’ could be used in the future to mask submarines from enemy sonars.  The cloak is made of metamaterial, a class of artificial materials that have enhanced properties as a result of their carefully engineered structure. A research team from the University of Illinois designed a two-dimensional cylindrical cloak made of 16 concentric rings of acoustic circuits structured to guide sound waves. Each ring has a different index of refraction, meaning that sound waves vary their speed from the outer rings to the inner ones.
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  Photonics OR opto-electronics In photonic crystals, the size and periodicity of the scattering elements are on the order of the wavelength rather than subwavelength.  subwavelength is used to describe an object having one or more dimensions smaller than the length of the wave with which the object interacts.  At optical frequencies(of GHz order) electromagnetic waves interact with an ordinary optical material (e.g., glass) via the electronic polarizability of the material.  This creates a state where the effective permeability of the material is unity, μeff = 1  Hence, the magnetic component of a radiated electromagnetic field has virtually no effect on natural occurring materials at optical frequencies.  However, the proper design of the elementary building blocks of the photonic metamaterial allows for a non-vanishing magnetic response and even for μ<0 at optical frequencies.  Photonic metamaterials, are a type of electromagnetic metamaterial, which are designed to interact with optical frequencies which are terahertz (THz), infrared (IR), and eventually, visible wavelengths.
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  Perfect absorber oflight  Researchers have engineered a new metamaterial that uses its unique geometric surface features to "perfectly" absorb all of the electric and magnetic properties of a microwave. Resonators couple individually to electric and magnetic fields to absorb all incident radiation.  Because its elements can separately absorb the electric and magnetic components of an electromagnetic wave, the "perfect metamaterial absorber" created by the researchers can be highly absorptive over a narrow frequency range.
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  Metamaterials for solarcells  The new metamaterial is particularly well suited to use in solar cells.  Scientists could potentially tune its index response to better match the solar spectrum, allowing for the development of broadband wide-angle metamaterials that could enhance light collection in solar cells.  And the fact that the metamaterial has a wide-angle response is important because it means that it can 'accept' light from a broad range of angles. In the case of solar cells, this means more light collection and less reflected or 'wasted' light.“
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  Recent Research  Researchersat the University of Central Florida have managed to create a large- scale invisibility cloak that masks the spectrum of visible light. This is significant, as invisibility cloaking has previously only been possible for very specific wavelengths of radiation (say, microwaves). Visible light, which covers a broad swath of terahertz-level frequencies, has so far proven very hard to mask.  The printed metamaterial sample is small — about 0.6 square inches (or four square centimeters) — but as it’s a printing process, the UCF team feels it can print the material on a larger-scale for more practical applications, such as for use on fighter jets.
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  Recent Research  LGElectronics’ new Chocolate BL40 mobile handset, from its high-end Black Label Series, will incorporate a metamaterial antenna made by San Diego–based Rayspan. LG is the first company to use metamaterials in mobile handsets. Metamaterials have allowed LG to "achieve the dramatically sleek, slim dimensions of the new LG Chocolate and unsurpassed radio- frequency capabilities.“  Metamaterial antennas satisfy this void by enabling the antennas to be sized on the order of one-tenth the signal’s wavelength and yet providing performance on par or better than conventional antennas sized one-half the signal wavelength, thereby providing a whopping five times the size reduction.  The antenna used in the LG handset is a few millimeters long and as thin as paper, and it simplifies the integration of both GPS and Bluetooth protocols. The same antenna array is also shared by the cellular and Wi-Fi radios within the handset.
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  Thank You!! Any Questions??