Electromagnetic metamaterials Metamaterial cloaking

electromagnetic metamaterials respond chosen parts of radiated light, known electromagnetic spectrum, in manner difficult or impossible achieve natural materials. in other words, these metamaterials can further defined artificially structured composite materials, exhibit interaction light not available in nature (electromagnetic interactions). @ same time, metamaterials have potential engineered , constructed desirable properties fit specific need. need determined particular application.

the artificial structure cloaking applications lattice design – sequentially repeating network – of identical elements. additionally, microwave frequencies, these materials analogous crystals optics. also, metamaterial composed of sequence of elements , spacings, smaller selected wavelength of light. selected wavelength radio frequency, microwave, or other radiations, beginning reach visible frequencies. macroscopic properties can directly controlled adjusting characteristics of rudimentary elements, , arrangement on, or throughout material. moreover, these metamaterials basis building small cloaking devices in anticipation of larger devices, adaptable broad spectrum of radiated light.

hence, although light consists of electric field , magnetic field, ordinary optical materials, such optical microscope lenses, have strong reaction electric field. corresponding magnetic interaction nil. results in common optical effects, such ordinary refraction common diffraction limitations in lenses , imaging.

since beginning of optical sciences, centuries ago, ability control light materials has been limited these common optical effects. metamaterials, on other hand, capable of strong interaction, or coupling, magnetic component of light. therefore, range of response radiated light expanded beyond ordinary optical limitations described sciences of physical optics , optical physics. in addition, artificially constructed materials, both magnetic , electric components of radiated light can controlled @ will, in desired fashion travels, or more accurately propagates, through material. because metamaterial s behavior typically formed individual components, , each component responds independently radiated spectrum of light. @ time, however, metamaterials limited. cloaking across broad spectrum of frequencies has not been achieved, including visible spectrum. dissipation, absorption, , dispersion current drawbacks, field still in optimistic infancy.

metamaterials , transformation optics

left:the cross section of pec cylinder subject plane wave (only electric field component of wave shown). field scattered. right: circular cloak, designed using transformation optics methods, used cloak cylinder. in case field remains unchanged outside cloak , cylinder invisible electromagnetically. note special distortion pattern of field inside cloak.

the field of transformation optics founded on effects produced metamaterials.

transformation optics has beginnings in conclusions of 2 research endeavors. published on may 25, 2006, in same issue of science, peer reviewed journal. 2 papers tenable theories on bending or distorting light electromagnetically conceal object. both papers notably map initial configuration of electromagnetic fields on cartesian mesh. twisting cartesian mesh, in essence, transforms coordinates of electromagnetic fields, in turn conceal given object. hence, these 2 papers, transformation optics born.

transformation optics subscribes capability of bending light, or electromagnetic waves , energy, in preferred or desired fashion, desired application. maxwell s equations not vary though coordinates transform. instead values of chosen parameters of materials transform , or alter, during time period. so, transformation optics developed capability choose parameters given material. hence, since maxwell s equations retain same form, successive values of parameters, permittivity , permeability, change on time. furthermore, permittivity , permeability in sense responses electric , magnetic fields of radiated light source respectively, among other descriptions. precise degree of electric , magnetic response can controlled in metamaterial, point point. since control can maintained on responses of material, leads enhanced , highly flexible gradient-index material. conventionally predetermined refractive index of ordinary materials instead become independent spatial gradients in metamaterial, can controlled @ will. therefore, transformation optics new method creating novel , unique optical devices.