Computing Sees the Light
By David Adams
Tuesday, September 1, 2009
It is about 50 years since the first microchip or integrated circuit was developed. Although it has served us well over the past half-century, the ongoing development of faster and more efficient computers means that the capacity and speed of electronic chips are nearing their limits.
In a bid to overcome the limitations of existing chips, researchers are now working on developing the next generation of integrated circuits. These chips will not rely on sending electrons along copper wires at speeds of up to one gigabyte per second; instead they will use fibre optic technology to transfer information at the speed of light.
More than 100 researchers from six Australian universities – Swinburne University of Technology, the University of Sydney, Macquarie University, the University of Technology, Sydney, the Australian National University and RMIT University – are involved in the project. It is being carried out under the auspices of the Centre for Ultra-High Bandwidth in Optical Systems (CUDOS), an Australian Research Council (ARC) Centre of Excellence. The project, which is funded by the ARC, began in 2003 and is funded until 2010.
Professor Ben Eggleton, the director of CUDOS, says the research is aimed at developing what is known as a ‘photonic chip’.
“The photonic chip has the potential to replace many electronic processing functions in optical communications systems and also underpins important applications in defence, healthcare and astronomy,†he says.
As part of the research program, scientists at Swinburne’s Centre for Micro-Photonics have been working on extending the photonic chip platform into the third dimension – a move that would give the chips more functionality and the ability to transfer more data.
The centre’s director, Professor Min Gu, says this process involves creating an artificial three-dimensional crystal – known as a ‘photonic crystal’ – out of polymer.
“It’s the equivalent of a semi-conductor for photons,†Professor Gu says of the photonic crystal.
Professor Gu and his colleague Dr Jesper Serbin pioneered the technique to create the crystal in 2003.
The technique involves focusing a high-powered laser into a liquid polymer, thereby turning it into a solid. The crystal has refraction qualities roughly 100 times greater than those of glass, which makes it suitable for high-precision technologies such as the optical chip.
To create a photonic crystal that acts in the same way as a semi-conductor in conventional microchips it must be made ‘active’. The active material acts as a source of photons.
“The ‘active’ semi-conductor is actually very important for the circuit,†Professor Gu says.
Dr Michael James Ventura, who, along with Dr Baohua Jia and Dr Jiafang Li at Swinburne, is part of the team working on the project at the Centre for Micro-Photonics, says the photonic crystal can be made active by embedding active material, such as quantum dots.
“Active material embedded within photonic crystals allows for a tailorable source of photons which can be switched on and off (modulated in an electronic circuit) or directed into particular directions (into another photonic crystal or another part of the optical chip),†he says.
As well as aiding the creation of the optical chip, the ability to control what are known as spontaneous emissions from the photonic crystal – the process in which an excited material relaxes to a more stable state by emitting a photon of light without any external stimulus – could have effects on a range of other fields including in solar cells used to capture solar energy, where performance could be significantly enhanced by controlling the spontaneous emissions.
Professor Gu says that by changing the way in which the active material interacts with sunlight, the efficiency of solar cells should be able to be dramatically increased.
The team is now investigating the possibility of completely shutting off spontaneous emissions.
Meanwhile, Professor Eggleton says that the development of the photonic chip will represent a platform for new technologies in areas such as healthcare, but notes that it is still “early days†in this development.
While noting that breakthrough technologies such as this can take as long as 15 years to cycle from a research concept through to application, Professor Eggleton says the project has already achieved “many important milestones†and adds that the team is now starting to work with end-users and industry.
Illustration
laughingstock.com/Randy Lyhus