The magical world of metamaterials

In recent years, there has been a burgeoning interest in rapidly growing field of metamaterials due to their unprecedented properties unattainable from ordinary materials. Veselago pointed out that a material exhibiting negative values of dielectric permittivity (¿) and magnetic permeability (¿) would have a negative refractive index. Generally speaking, the dielectric permittivity (¿) and the magnetic permeability (¿) are both positive for natural materials. In fact it is possible to obtain negative values for ¿ and ¿ by utilizing proper designs of metamaterials. Left-handed electromagnetism and negative refraction are achievable with artificially structured metamaterials exhibiting negative values of permittivity and permeability simultaneously at a certain frequency region. The first steps to realize these novel type of materials were taken by Smith et al., where they were able to observe a left-handed propagation band at frequencies where both dielectric permittivity and magnetic permeability of the composite metamaterial are negative. Soon after, left-handed metamaterials with an effective negative index of refraction are successfully demonstrated by various groups.