Different-shaped beams could increase fibre-optic capacity, easing Internet congestion.
Twisty beams of light could boost the traffic-carrying capacity of the Internet, effectively adding new levels to the information superhighway, suggests research published today in Science1.
Internet traffic is growing exponentially and researchers have sought ways to squeeze ever more information into the fibre-optic cables that carry it. One successful method used over the last 20 years essentially added more traffic lanes, using different colours, or wavelengths, for different signals2. But to compensate for the added lanes, each one had to be made narrower. So, just as in a real highway, the spacing could get only so tight before the streams of data began to jumble together.
In the last few years, different groups of researchers have tried to encode information in the shape of light beams to ease congestion, using a property of light called orbital angular momentum. Currently, a straight beam of light is used to transmit Internet signals, but certain filters can twist it so that it corkscrews around with varying degrees of curliness as it travels.
Previous experiments using this effect have found that differently shaped light beams tend to jumble together after less than a metre3, 4.
Now, a team of researchers from Boston University in Massachusetts and the University of Southern California in Los Angeles has found a way to keep the different light beam shapes separated for a record 1.1 kilometres.
The researchers designed and built a 1.1-kilometre-long glass cable, the cross section of which had a varying index of refraction — a measure that describes how fast light can travel in a particular medium. They then sent both twisty and straight beams of light down the cable...
(Excerpt) Read more at nature.com ...
