Monday, May 23, 2011

Laser Smashes Information Rate Records

Researchers have set a new record is to rate of information give using a singular laser: 26 terabits per second.

At those speeds, the whole Library of Congress collections could be sent down an visual twine in 10 seconds.

The pretence is to use what is well known as a "fast Fourier transform" to unpick more than 300 well-defined colours of light in a laser beam, any encoded with its own string of information.

The technique is described in the biography Nature Photonics .

The pull for aloft information rates in light-based telecommunications technologies has seen a number of poignant leaps in new years.

While the beginning visual twine technologies encoded a string of information as "wiggles" inside of a singular colour of light sent down a fibre, newer approaches have used a number of tricks to enlarge information rates.

Among them is what is well known as "orthogonal magnitude section multiplexing", that uses a number of lasers to encode not similar strings of information on not similar colours of light, all sent by the twine together.

At the reception end, other set of laser oscillators may be used to collect up these light signals, reversing the process.

While the complete information rate probable using such schemes is paltry usually by the number of lasers available, there are costs, says Wolfgang Freude, a co-author of the stream paper from the Karlsruhe Institute of Technology in Germany.

"Already a 100 terabits per second examination has been demonstrated," he told BBC News.

"The complaint was they didn't have just a laser, they had something similar to 500 lasers, that is an incredibly costly thing. If you can suppose 500 lasers, they expand racks and devour tens of kilowatts of power."

Professor Freude and his colleagues have instead worked out how to emanate comparable information rates using just a laser with awfully partial pulses.

Within these pulses are a number of several colours of light in what is well known as a "frequency comb".

When these pulses are sent in to an visual fibre, the not similar colours can add or subtract, blending together and developing about 350 not similar colours in total, any of that may be encoded with its own information stream.

Last year, Professor Freude and his collaborators initial demonstrated how to use all of these colours to broadcast over 10 terabits per second.

At the reception end, normal methods to well-defined the not similar colours will not work. Here, the researchers have implemented what is well known as an visual swift Fourier renovate to unpick the information streams.

The Fourier renovate is a well-noted arithmetic pretence that can in hint remove the not similar colours from an submit beam, formed solely on the times that the not similar tools of the lamp arrive.

The group does this optically - rsther than than mathematically, that at these information rates would be unfit - by bursting the incoming lamp in to not similar paths that arrive at not similar times, recombining them on a detector.

In this way, stringing together all the information in the not similar colours turns in to the easier complaint of organising information that basically arrives at not similar times.

Professor Freude mentioned that the stream pattern outperforms progressing approaches simply by relocating all the time delays serve apart, and that it is a technology that could be integrated onto a silicon fragment - creation it a improved participant for scaling up to blurb use.

He concedes that the thought is a intricate one, but is assured that it will advance in to its own as the urge for ever-higher information rates drives innovation.

"Think of all the extensive growth in silicon photonics," he said. "Nobody could have illusory 10 years ago that today it would be so familiar to confederate comparatively complicated visual circuits on to a silicon chip."

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