A property of a material that changes the speed of light, computed as the ratio of the speed of light in a vacuum to the speed of light through the material. When light travels at an angle between two ...

A rainbow reveals with colors what otherwise remains hidden: light is "refracted" by transparent matter, in this case water ...

Physicists at Harvard University in the US have built a silicon waveguide that exhibits a refractive index of, or close to, zero when operating at near-infrared telecom wavelengths. The waveguide can ...

At the interface between two facets of an artificial crystal, sound waves can be transmitted in the opposite direction to that expected, and undergo no reflection. Such wave behaviour could have many ...

Scientists have demonstrated that negative refraction can be achieved using atomic arrays -- without the need for artificially manufactured metamaterials. Scientists have long sought to control light ...