COMPUTERS CLOSER TO THE SPEED OF LIGHT

Australian scientists have used their expertise in solar cells to develop a more efficient silicon light-emitting diode, providing a new platform for faster computing and data transfer.
The development, reported in 23 August  2001 Nature by Martin A. Green and colleagues at the University of New South Wales, will mean microelectronics can take better advantage of the speed of optical data transfer.
"The speed of all optical communication is limited because of electronic bottlenecks," explains Dr Gerard Milburn, Deputy Director of the Special Research Centre for Quantum Computing Technology.
Light-emitting diodes (LEDs), which convert electricity into light, are most familiar in the form of giant display screens such as those in football stadiums. However, they are also central to high-bandwidth communication technologies, which rely on optical information transfer.
Data transfer between computers has been made faster by the use of optic fibres, but information within computers is currently still in the form of electrical signals. These electrical signals must be converted to light and back again at both ends using LEDs, creating a bottleneck which slows data flow.
At the moment, LEDs are placed in the communications cabling system at some distance from the computer, further slowing data.
"The aim is to bring the conversion as close as possible to where the information will be processed," says Milburn. Ideally, this would mean LEDs integrated into the computer's actual silicon chip.
So far this has not been possible because most LEDs are made of exotic materials not compatible with silicon-based microelectronics. And existing silicon LEDs do not transmit light well, suffering from efficiencies of less than 0.1 per cent - often less than 0.01 per cent.
The new silicon LED made by Professor Green's team, however, is 1 per cent efficient, emitting light near to room temperature about 100 times more efficiently than most existing devices.
This high-efficiency silicon LED now makes it possible to interconvert optical and electrical signals within the computer.
The team used knowledge developed over the past decades for silicon solar cells to achieve the gain in LED efficiency.
"Solar cells absorb light and convert it into electricity, so they do the reverse process to light emitting diodes," Professor Green said.
"It turns out there's a relationship between the ability of silicon to absorb light well and to emit it well".

Optical computing?

The use of silicon LEDs such as the one developed by Green and colleagues could eventually lead to the use of optical signals between chips within the computer, thus eliminating the need for wires.
"It's terrific stuff," says Professor Mark Sceates, CEO of the Australian Photonics Cooperative Research Centre.
"In about three generations of silicon chip from now, photonics - the use of light - will be essential to computing."
Professor Sceates says his centre will consider the new device in their research project exploring ways to increase bandwidth, which last week was awarded a $9.5 million grant through the Australian Federal Government's Major National Research Facilities program.
Professor Sceates believes that in as little as six years, the speed of computer chips will be so high that the wires connecting them will be a limiting factor.
The use of silicon LEDs such as the one developed by Green and colleagues could be one approach to integrating the speed of optics into microelectronics, he said.

Source of the given news and the copyrights belong to a ABC Online News

Back