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Last Updated: Monday, 6 February 2006, 13:15 GMT
Lighting the way to a revolution
By Rebecca Morelle
BBC News science reporter

A bunch of optical fibres (EyeWire)
Fibre optics have changed the face of modern communications
The information superhighway owes its very existence to fibre optics.

With a very thin tube, light and some engineering know-how you have the components for speeding information around the world.

The communication revolution was set in motion 40 years ago, when a landmark paper was revealed to the engineering community.

In 1966, Dr Charles Kuen Kao and George Hockham, both young research engineers from the Standard Telecommunications Laboratories, addressed a meeting at the Institute of Electrical Engineers in London with their exciting new findings on the possibilities of optical fibres.

Optical fibres are transparent rods of glass or plastic stretched until they are extremely long, flexible and thinner than a human hair.

Escaping light

They carry information using a process called total internal reflection. A message is turned into light pulses, which then travel along the fibre, bouncing through the tube at such an angle that hardly any light is lost to processes such as refraction.

This means that the light ray, and therefore the message, can arrive in their entirety at the other end of the fibre.

Before 1966, the use of fibre optics for communication was extremely limited.

Messages could only travel for a few metres before light began to be lost from the fibre, a process called attenuation which is measured in decibels per kilometre, where the loss of one decibel means a fall of about 20% of the signal strength.

A lot of people just openly laughed at the paper
Prof Midwinter, UCL
This made them unsuitable for communication over long distances, but Kao and Hockham's paper was to transform this perception.

The fibres they had been observing had the capability of carrying one gigacycle of information - the equivalent of 200 television channels or 200,000 telephone lines.

However, light was being lost at a rate of 1,000 decibel per kilometre, meaning that the signal was less than half the original by the time it had travelled a few metres.

But the breakthrough came when Dr Kao worked out that the loss of light was not an inherent property of the glass, but was due to imperfections in the material.

If the glass could be improved so that imperfections were removed, leaving an acceptable rate of light loss at 20 decibels per kilometre, then many of the hurdles to optical communication would fall.

Initial scepticism

Professor Charles Kao, who is now chairman and CEO of ITX services, told the BBC News website of the intense pressure of working on such a groundbreaking area.

"At the time I told my annoyed wife, as I was always late home for dinner, that it could be a world shaking project! She told me to 'pull the other leg' in absolute disbelief," he said.

"I think I sensed it at the time, but I knew I would need to convince the industry worldwide."

John Midwinter, a fibre optics expert and emeritus professor at University College London, spoke of the engineering community's scepticism when the paper was announced: "A lot of people just openly laughed at the paper. At that time, you'd have been lucky to get this 20 decibel transmission through a few metres of cable."

Photo of Prof Charles Kuen Kao (courtesy Prof. Kao)
Professor Kao's research was initially greeted with disbelief
But eventually, the world began to come around to the idea which has proved to be the backbone of optical communication technology.

"What Charlie Kao did rather beautifully was to sit down and think, 'if I am going to guide information through an optical fibre cable, what must the performance of that fibre be if it is going to have any chance of competing with the existing technology?' which was coaxial cable at the time," Prof Midwinter told the BBC News website.

"He not only set out a vision, he said, 'here is what you need to make it, here are the dimensions to make it to, and here is the optical performance you must achieve if you are going to be taken anyway seriously by the telecoms industry'. I think that it was this combination together that gave the paper its impact."

It was not until four years later, in 1970, that Corning Glass Works made the dramatic announcement it had produced an optical fibre so pure it had broken the 20 decibel limit.

"Corning took a long shot of trying to work with a very, very pure silica glass, while everyone else was looking at purifying ordinary glass," said Jeff Hecht, author of City of Light: The Story of Fiber Optics.

"They took a different route and hit the jackpot."

'Internet bubble'

In the subsequent years, exciting new progressions brought ever-purer optical fibres and new transmission techniques that made it possible to carry messages over longer and longer distances.

In the late 1970s, telecommunication companies started to use the fibre networks, trailing the technology around the UK.

A few years later, great stretches of roads were dug up and new optical fibres laid in Britain, and cables also began to be positioned under the sea.

As the fibre gets closer and closer to the end user, you can start to provide them with more sophisticated services
Dr Hargrave, Nortel
There was anticipation of a great rush to use the fibres, but the technology did not truly take off until the 1990s.

One area in particular that exploited the fibre optic networks was the internet.

"In a lot of ways, fibre optics was such a dramatic success that it created a lot more bandwidth than anyone knew what to do with - it really helped create the internet bubble," Hecht told the BBC.

"The whole telecommunications industry had been brought up, nurtured and matured on the idea that information transmission capacity over long distances was scare.

"So when all of a sudden they kept on having more and more bandwidth, they kept laying more fibre thinking that they would fill it up, when of course they exceeded the demand," he explained.

Silent enabler

But the internet is not the only technology that has fibre optics to thank for its underlying success.

"It [fibre optic technology] underpins WiFi, it underpins the internet. Every business that has a local area network uses it. You use it every time you send an e-mail, sms, picture or video; every time you send data or files," Dr Philip Hargrave, a chief scientist at Nortel, a communication solutions provider, said.

"The fibre optic silently enables all these things," he added.

Photo of demonstration of fibre optic video communication to HRH Queen Elizabeth II  (Estate of Murray Ramsay)
In 1971, the Queen saw a demonstration of video communication using fibre optics
Fibre optics will also play a key part in areas such as Internet Protocol Television (IPTV), where digital television can be watched over the internet, and Dr Hargrave believes that in the near future it will play a new role in how we manage information at home.

"At the moment we are in a situation were we haven't got fibre going all the way to the end user. You and I at home are limited in what we can do by the capacity of our broadband connection. As a result, we store lots of data and do lots of things on our network at home," he said.

"But as the fibre gets closer and closer to the end user, you can start to provide them with more sophisticated services such as software backup and file storage. This is the way forward."

As the applications move forward, so will the technology itself and companies, such as Nortel, are now looking into ways of using digital processing techniques to improve the signal and lessen costs.

I only hope that my opening of the Pandora box will bring much joy to the world
Prof Charles Kuen Kao
Looking back to 1966, it is hard to imagine the phenomenal triumph of fibre optics.

"It has been a huge success story. Without fibre optics the internet wouldn't have happened; you couldn't just pick up the phone and call New York. Fibres circle the globe and go everywhere under the sun now," Professor Midwinter said.

"I think Charlie Kao must have been absolutely delighted to see the success, but I think it probably vastly exceeded his wildest dreams. I don't think anyone had appreciated how this thing was going to take off like a rocket."

Professor Kao himself has great hopes for the future.

"I only hope that my opening of the 'Pandora box' will bring much joy to the world and not the reverse."

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