Communicating with light – fibre optics
Box 1 | The Australia Prize
Fibre optics and telecommunications have certainly made some extraordinary advances in the last few decades, but who are the scientists behind this work? The Australia Prize – the closest award Australia has to Sweden's famous Nobel Prize – was recently shared by three eminent telecommunications experts: Professor Allan Snyder in Canberra, Professor Rodney Tucker in Melbourne, and Dr Gottfried Ungerboeck in Zürich, Switzerland. Here is a little bit about their work.
Professor Allan Snyder
Early in his career, Professor Snyder studied how photoreceptors in the retina of the human eye transmit light images to the brain. At the time he had no interest in telecommunications, but in the course of his retina work, he was struck by the similar light transmission properties of photoreceptors and optical fibres.
This led him to study how light travels down an optical fibre. There was already a theory describing this, but because it was complex it was very difficult for engineers to apply it to optical fibres. Professor Snyder worked to simplify the theory.
Professor Snyder's work became the basis of the theory on light transmission in an optical fibre, which in turn made optical fibre technology possible. From this start, telecommunications was revolutionised, with millions of kilometres of fibre optic cable being laid around the world.
Professor Rodney Tucker
Professor Rodney Tucker specialises in creating devices which help control the transmission of light through optical fibres.
Professor Tucker's research in the early 1980s led to a ten-fold increase in the carrying capacity of the fibre optic network. His research resulted in a new class of devices which are now used internationally.
Professor Tucker sees the day when telecommunications will allow people to be in two places at once (well almost). Their 'real' self will be almost indistinguishable from their 'virtual' self somewhere else. Professor Tucker calls this 'telepresence'.
Telepresence will come from a merging of virtual reality, high definition/three dimensional television and telecommunications. It will allow a person to sit in their home or office using goggles or perhaps a helmet and be able to attend a meeting at a distant place.
What they'll see and hear will be like actually being there. Other people at the meeting will share the same virtual experience. Professor Tucker says that using telepresence, sports fans will be able to attend major events from their lounge chair. It'll be as if they were in the stadium for big games, no matter where they're held.
Dr Gottfried Ungerboeck
The old telephone system was designed to transmit the sound of people talking, but it didn't work well when used to communicate between computers. Computer information (data) could be sent on phone lines only if the rate of transmission wasn't too fast (a maximum of 9600 bits per second). When engineers tried to make it go faster, the distortion which you can hear (but ignore) on most phone lines wrecked the messages sent by computers. To get around this problem, Dr Ungerboeck used his mathematical talents to invent an information coding system called trellis-coded modulation. Dr Ungerboeck's system made it possible to transmit data reliably over ordinary telephone cables at far higher speeds than was ever dreamed of.
Using his revolutionary coding system, Dr Ungerboeck was able to represent data in a different way so that the distortion on the telephone line was much less of a problem.
When Dr Ungerboeck's trellis-coded modulation system was used, modem speed went up from 9600 to 14,400. Most modems now transmit at 28,000 bits per second and beyond. Trellis-coded modulation helped remove the log jam in world communications.
These three winners have helped make telecommunications what it is today – without them the information super-highway might be just a slow and bumpy bush track!
Boxes
Box 2. Digital communication
Box 3. Binary numbers
Related sites
Allan Snyder – Optical Physicist/Visual Scientist (Tall Poppy Campaign, Australian Institute of Political Science)
Australian Photonics CRC
Posted May 1997.