Metamaterials–invisibility cloaks and more…

There’s a new type of material you likely haven’t heard of—metamaterials. These artificial materials can be tailored to exhibit specific properties, potentially to make superlenses (resolves objects a few nanometers apart) or even coatings that can make objects invisible [1]. Metamaterials is such a hot topic for scientists/engineers that there is even a journal solely dedicated to the research of it–known as Metamaterials.

How did metamaterials come about? Viktor Veselago is credited for this new research direction in physics when he hypothesized a material exhibiting both negative electric permittivity and magnetic permeability would create a material with a negative index of refraction [2]. Although a negative index of refraction is unattainable with naturally occurring materials, Veselago’s hypothesis was left ignored until about thirty years later when Smith et al. designed an artificial material showing a negative index of refraction was indeed achievable [2].

In  a recent issue of IET Microw. Antennas Propag., Lapine and Tretyakov give an analogy of metamaterials as being composed of elements like an ordinary material is composed of atoms. The important difference is that the size of metamaterial elements is smaller than the wavelength of light, giving metamaterials extraordinary optical properties that do not exist in nature. Examples of elements include programmable microcomputers or electronic circuits [3]. Since elements can be individually  selected, specific properties can be combined together. Furthermore, these properties can be adjusted and controlled during usage of the material. It is important to note that although metamaterials are artificially created they still follow the fundamental laws of physics. As unusal as the properties may be, metamaterials still follow the established theories of electromagnetism [3].

Metamaterials are not limited to materials with a negative refractive index. They can also be bi-anisotropic. Bi-anisotropic metamaterials have a mutually dependent electric and magnetic response, meaning a magnetic field causes electric polarisation and vice versa [3]. Such properties are not observed in naturally occurring materials, thus these unique materials are  transforming how materials can be used.

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[1] Di Falco, A., Ploschner, M. & Krauss, T.F. (2010). Flexible metamaterials at visible wavelengths New Journal of Physics 12

[2] Shamonina, E., & Solymar, L. (2007). Metamaterials: How the subject started Metamaterials 1(1) 

[3] Lapine, M., & Tretyakov, S. (2007). Contemporary notes on metamaterials IET Microwaves, Antennas & Propagation, 1 (1) DOI: 10.1049/iet-map:20050307

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2 responses to “Metamaterials–invisibility cloaks and more…

  1. Pingback: Invisibility Cloaks: Now you see it, Now you don’t. « Basal Science Clarified·

  2. Pingback: » ‘Invisibility Cloak’ Successfully Hides Objects Placed Under It·

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