Negative-Index Metamaterials

Abstract

The refractive index is one of the most important parameters for an optical medium. Defined as n = c/v, it measures the comparative velocity of light in different media. When a light beam travels across the boundary between two different materials, it bends owing to the change in refractive index at the interface. This phenomenon, refraction, gives the reason why a water pool appears shallower than it actually is, why a straw placed partially in water at a slant seems to bend towards the surface, and why people can use eyeglasses to adjust the path of light in front of their eyes and alleviate the effects of conditions such as myopia.