acoustic band gap
Journal Club December 2007: Elastodynamic band gaps and metamaterials
Submitted by Biswajit Banerjee on Thu, 2007-11-29 20:50.Metals have a lustre because electromagnetic radiation in the visible range is almost completely absorbed at an exponential rate close to a metal surface and then radiated back. This effect and other properties of crystalline materials can be explained by their electronic band structure and the associated dispersion relations. In certain materials, notably semiconductors, distinctive band gaps are found indicating that electrons of certain forbidden energies which cannot propagate through the material. A concise description of the basics can be found here.
There is a close analogy between the motion of electrons in periodic crystals and electromagnetic waves in periodic dielectric structures. This analogy and the quest for materials with unusual electromagnetic properties has led to exploration of periodic materials with tunable electromagnetic band structures and band gaps. Such materials are called photonic crystals and photonic composites. A good review article on the subject is E. Yablonovitch, 1993, "Photonic band-gap crystals", J. Phys.: Condens. Matter, 5, 2443-2460, doi:10.1088/0953-8984/5/16/004.
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