Electromagnetic Metamaterials are man-made structures whose extraordinary properties can be defined and manipulated by engineering the distribution and type of their unit-cells. They possess unusual properties including (not limited to) negative refractive index and cloaking devices which cannot be realized in natural materials. In particular, the latter application of metamaterials (i.e. cloak of invisibility) seems to make a human dream (imagination) come true.
Indeed, this field of research is very immature and new. It is basically started in the last years of 20th century when Sir. John Pendry proposed using of split-ring resonator for extraordinary magnetic properties.
Later in 2000, he proposed that negative refractive index which can be realised through metamaterial can be ultimately used for fabrication of perfect lens, a device that can provide images without possessing the limits of conventional lenses (i.e. diffraction limit). This innovative idea boost the research field of metamaterials and nowadays hundreds of research groups globally are working on this cutting edge field of research.
So far, various types of metamaterials have been developed for different operation frequencies ranging from ultraviolet to mid-infrared but the further technological development are required to push this class of materials from lab to large scale application. The current obstacle against the further development of metamaterial for practical devices is the narrow band of operation. It means they work solely for a single frequency in which the unit-cells interact with the incident electromagnetic waves. In future posts some more detailed information of the concepts will be discussed.
- V.M. Shalaev, Optical negative-index metamaterials. Nature photonics 2007, 1(1), pp.41-48.
- N. Engheta, R.W. Ziolkowski, eds., 2006. Metamaterials: physics and engineering explorations. John Wiley & Sons.
- D. Schurig, J.J. Mock, B.J. Justice, S.A. Cummer, J.B. Pendry, A.F. Starr, D.R. Smith, Metamaterial electromagnetic cloak at microwave frequencies. Science 2006, 314(5801), pp.977-980.