Trapped Rainbow

Scientists in Britain said Wednesday they were able to slow and then stop a squirt of light in what they described as a key step towards the future of ultra-fast computing. [...] The innovation exploits a principle called the Goos-Haenchen effect, an optical phenomenon discovered 60 years ago that happens to polarised light travelling in a straight line. When this light hits an object or an interface between two media, it does not immediately bounce back but travels very slightly along that object. In the case of metamaterials, the light in fact travels very slight backwards along the object. Hess conjectured creating a prism "sandwich" -- a tapered layer of glass, surrounded by two layers of negative refractive index metamaterials. A packet of white light injected into the glass from the wide end of the prism slows as it travels down the taper and eventually comes to a standstill. The description of it as a "trapped rainbow" derives from the fact that the constituent frequencies of white light are the colours of the rainbow -- red, orange, yellow, green, blue, indigo and violet. Each individual frequency is stopped at a different point down the taper, until finally the light is stopped. Full article @ PhyOrg.com