and Prof W L Barnes
Structuring materials on the subwavelength scale produces new types of electromagnetic material properties leading to effects such as negative refraction and consequentially perfect lensing and cloaking. However the use of double structuring, that is metametamaterials appears to be in its infancy (although televisison aerials have done this to some degree already). This means combining material subunits which have structurally defined permittivities or permeabilities in a 'super-array' with further different properties. For example at microwave frequencies one can envisage a hollow sub-structured metallic cube in which the inside of the cube is filled with high permeability material then when such structured filled cubes are stacked into a lattice with the regions between the cubes filled with high permittivity material one ends up with quite remarkable electromagnetic properties of the collective whole. Once can also imagine this more readily in 2D where local metallic metamaterial structures give an unusual response but when stacked together in an array leads to an overall novel and unexpected microwave response.