Now that IS fast! Scientists transfer 700 DVDs of data down a single fibre-optic cable in ONE SECOND
Posted May 24, 2011on:
The researchers believe that their new super-fast data-transfer technology is ripe for commercial use
A new speed record has been set for transferring data down a fibre-optic cable using a single laser.
Researchers at Karlsruhe Institute of Technology in Germany succeeded in sending 26 terabits of data – the equivalent of 700 DVDs – down an optical fibre in one second.
They used a ‘fast Fourier transform’ to separate more than 300 colours of light in a laser beam, each encoded with its own string of information, said the journal Nature Phonetics.
Attempts to perfect higher data transfer rates in light-based telecommunications technologies have led to significant developments in recent years.
Early optical fibre technologies encoded data as ‘wiggles’ within a single colour of light but in recent years a number of other methods have been used to increase speeds.
‘Orthogonal frequency division multiplexing’, for example, uses a number of lasers to encode strings of data on different colours of light then sends them through the fibre together.
At the receiving end, another set of laser oscillators is used to reverse the process.
Using this method the rate at which date can be transferred is limited only by the number of lasers used, said Wolfgang Freude, a co-author of the institute’s study.
‘Already a 100 terabits per second experiment has been demonstrated,’ Mr Freude told BBC News. ‘The problem was… they had something like 370 lasers, which is an incredibly expensive thing.
‘They fill racks and consume several kilowatts of power.’
But Professor Freude and his colleagues have now worked out how to replicate similar speeds using a single laser with extremely short pulses. A number of discrete colours of light, known as a ‘frequency comb’ exist within these pulses.
Once sent into an optical fibre, the colours can add or subtract, mixing together and creating about 325 colours, each of which can be encoded with its own data stream.
Professor Freude’s team demonstrated how a smaller number of these colours could be used to transmit more than 10 terabits per second last year.
At high speeds traditional methods used to separate the different colours at the receiving end do not work. In their latest experiment, the team successfully received and unpicked data streams after sending them down 50km of optical fibre.
The Fourier transform extracts the colours from an input beam on the basis of when the different elements of the beam arrive.
Professor Freude’s team does this optically – rather than mathematically, which would not be possible at such high transfer rates – by splitting the incoming beam into different paths that arrive at different times and recombining them on a detector.
Thus, stringing together the data in the various colours becomes a simpler problem of organising data that arrives at different times.
Professor Freude said that his new design outperforms earlier models simply by creating a greater separation in the time delays.
It would be possible to place the technology on a silicon chip, he added, which meant it would be ripe for commercial exploitation.
Though the idea is a complex one, Professor Freude is convinced that it will be in demand as ever-higher data rates become desirable.
‘Think of all the tremendous progress in silicon photonics,’ he said. ‘Nobody could have imagined ten years ago that nowadays it would be so common to integrate relatively complicated optical circuits on to a silicon chip.’