Colourful solution: By exploiting the different frequencies that comprise the light spectrum and by slowing, stopping and capturing these frequencies, the technology may open up the way for a massive boost in data handling.

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PARIS: British scientists have been able to slow and then stop a 'squirt' of light in what they described as a key step towards the future of ultra-fast computing.

The technique, called "trapped rainbow," would help optical data storage, with light replacing electrons to store information, according to their paper, released by the U.K. journal Nature.

Controlling light would also help engineers control major nodes where billions of optical data "packets" arrive at the same time. By slowing some packets to let others through, rather like a traffic congestion scheme, the flow of data can be boosted.

Optical data packets

The research, by Ortwin Hess, a professor at the University of Surrey at Guildford, England and postgraduate student Kosmas Tsakmakidis, is based on the so-called "negative refractive index" of metamaterials.

Metamaterials are novel materials with metal components that are smaller than the wavelength of light, while the refractive index measures the slowing of light when it passes through an object.

The innovation exploits a principle called the Goos-Haenchen effect – an optical phenomenon discovered 60 years ago that happens to polarised light travelling in a straight line.

When this light hits an object or an interface between two media, it does not immediately bounce back but travels very slightly along that object. In the case of metamaterials, the light in fact travels very slight backwards along the object.

Hess conjectured creating a prism "sandwich" – a tapered layer of glass, surrounded by two layers of negative refractive index metamaterials. A packet of white light injected into the glass from the wide end of the prism slows as it travels down the taper and eventually comes to a standstill.

Trapped rainbow

The description of it as a "trapped rainbow" derives from the fact that the constituent frequencies of white light are the colours of the rainbow – red, orange, yellow, green, blue, indigo and violet.

Each individual frequency is stopped at a different point down the taper, until finally the light is stopped. "It's like wading through snow, it gets more and more sluggish," said Hess. Eventually, "it just sits there and gets trapped."

In a press release, the researchers said that by exploiting the different frequencies that comprise the light spectrum and by slowing, stopping and capturing these frequencies, the way was open for a massive boost in data handling.

"The technique would allow the use of light rather than electrons to store memory in devices such as computers, enabling an increase in operating capacity of 1,000 per cent," said the release. "Previous attempts to slow and capture light have involved extremely low or cryogenic temperatures, have been extremely costly and have only worked with one specific frequency of light at a time."