Australian scientists believe they are on the verge of a breakthrough in optical circuitry that may improve the speed of the internet by a factor of 1000.
The Centre for Ultrahigh bandwidth Devices for Optical Systems, a research consortium of five universities, is trying to create a photonic chip that processes optical signals free of slow, silicon electronics.
Optical-signal processing allows unprecedented bandwidth - one optical fibre has a capacity of hundreds of terabits a second. At this speed, a high-definition movie could be downloaded in a fraction of a second, rather than the hours it takes with current technology.
Today, our international internet links are bedevilled by unavoidable lag - the time it takes for data to travel from the US to a user's PC in Australia.
For most of its journey, the data travels at the speed of light along optical fibres. But each time the information stream is switched, amplified, reprocessed or regenerated, it requires silicon-based electronics, which are much slower.
These bottlenecks stand in the way of a 1000-fold increase in the practical speed of the internet, the centre's researchers say. But they could be removed with optical computing, which uses light to switch light, without electronic interference.
Research director Ben Eggleton says the centre's program has four strands: a "regenerator" that reproduces an optical signal without electronics; a switch that uses a light signal to direct another light signal; optical buffers to slow light pulses, making them easier to handle; and three-dimensional photonic circuits.
The centre's participants at Sydney University and the Australian National University are about a month away from demonstrating an optical switch, he says. (The centre's other members are Macquarie University, University of Technology Sydney, and Swinburne University of Technology.)
Although scientists around the world work on the same problem, Professor Eggleton says the centre takes a unique approach.
It is working with a soft glass called chalcogenide, which changes its refracting properties when hit by high-intensity pulses of light - becoming a basic switch. The glass switches at very low powers, which makes it easier to work with and promises more practical applications.
Chalcogenide can also be printed, to create circuits. Scientists created "band gap" structures within the glass - patterns of tiny holes that further control the light beams. Professor Eggleton says this band gap could be the photonic equivalent of the basic unit of electronics - the semi-conductor.
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