THINK your broadband internet connection is fast? Two separate research groups have just lapped the field, setting a world record by sending more than 100 terabits of information per second through a single optical fibre. That’s enough to deliver three solid months of HD video- or the contents of 250 double-sided Blu-ray discs.
This marks “a critical milestone in fibre capacity”, says Ting Wang at NEC Laboratories in Princeton, New Jersey.
Such lab results are far beyond today’s commercial needs. Total capacity between New York and Washington DC, one of the world’s busiest routes, is only a few terabits per second, says Tim Strong, of Telegeography Research in Washington. But “traffic has been growing about 50 per cent a year for the last few years”, he adds. With bandwidth-hungry video-streaming and social media growing relentlessly, network planners are always searching for ways to expand capacity.
Today’s fibre optics use several tricks to enhance bandwidth. Like the radio band, the optical spectrum can be sliced into many distinct channels that can simultaneously carry information at different frequencies. The laser light is pulsed on and off rapidly, with each pulse further sliced up into different polarities, amplitudes and phases of light, each of which contains a bit of information. The trick is to pack all these signals together in one fibre so that they hit the receiver as one pulse without interference.
New Scientist
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