Light Controlling Light

A team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light – both slowing it down and speeding it up – in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions. Their results, to be published in Applied Physics Letters, could have implications that range from optical computing to the fiber-optic telecommunications industry.

Let there be light! (Courtesy: Griffith University)On the screen, a small pulse shifts back and forth – just a little bit. But this seemingly unremarkable phenomenon could have profound technological consequences. It represents the success of Luc Thévenaz and his fellow researchers in the Nanophotonics and Metrology Laboratory at EPFL in controlling the speed of light in a simple optical fiber. They were able not only to slow light down by a factor of three from its well – established speed c of 3x10⁶ meters per second in a vacuum, but they've also accomplished the considerable feat of speeding it up – making light go faster than the speed of light:D.
The telecommunications industry transmits vast quantities of data via fiber optics. Light signals race down the information superhighway at about 186,000 miles per second. But information cannot be processed at this speed, because with current technology light signals cannot be stored, routed or processed without first being transformed into electrical signals, which work much more slowly. If the light signal could be controlled by light, it would be possible to route and process optical data without the costly electrical conversion, opening up the possibility of processing information at the speed of light!!
This is exactly what the EPFL team has demonstrated. Using their Stimulated Brillouin Scattering (SBS) method, the group was able to slow a light signal down by a factor of 3.6, creating a sort of temporary optical memory. They were also able to create extreme conditions in which the light signal travelled faster than light in vacuum. And even though this seems to violate all sorts of cherished physical assumptions, relativity isn't called into question, because only a portion of the signal is affected:):).