1202nd Ordinary General Meeting

"Photonic circuits for the new information age: faster, smaller, smarter and greener"

Ben Eggleton, Professor of Physics, ARC Federation Fellow, Director of the Centre of Excellence for Ultrahigh-bandwidth Devices for Optical Systems (CUDOS) and Director of the Institute of Photonics and Optical Science (IPOS)

Wednesday 1 August 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by Donald Hector

The ARC Centre for Excellence for Ultrahigh-Bandwidth Devices for Optical Systems (CUDOS) is a world-leader in research in photonics and the development of photonic devices. Its director, Professor Ben Eggleton, gave a wide-ranging talk about the Centre's work and photonics generally.

The use of light to communicate information is by no means a novel concept. Signals such as flags and lights for sending information have been used for many hundreds if not thousands of years. In the last couple of hundred years, various systems have been devised such as collimators and various lens systems. Three major breakthroughs of the last half-century or so were the invention of microelectronic devices, the invention of the laser and, importantly, the discovery by Charles Kao in 1966 that the physical properties of glass fibres were ideal for transmitting optical signals. Photonics, which combines these technologies, provides extraordinary capability for extremely high-speed transmission of data through optical fibre.

The reason that glass fibre is suitable is that there is a narrow part of the absorption spectrum in glass about 25 THz wide where attenuation of the signal is only about 0.2 dB per kilometre. Lasers can generate discrete packets of visible light light that can be transmitted down the fibre. Importantly, the photons do not interfere with one another and can be separated at the other end and the data encoded in the packets of light can be read. The relatively small signal loss can be managed by periodically installing amplifiers along the fibre-optic cable. There are now fibre-optic networks joining all major continents and these are the primary means for moving digitised data around the world.

A significant advantage of this fibre-optic technology has been its scalability. Developments in photonics and vastly increased the capacity of fibre-optic cables since the first ones were laid over 20 years ago. The National Broadband Network that Australia is currently installing is intended to deliver 1 Mb per second to well over 90% of households in Australia. There has been some speculation that this may become obsolete but this is unlikely as technological pathways to upgrade this to one terabit per second are already on the horizon.

One of the areas that CUDOS is working in is the application of nanotechnology and the development of materials with physical properties that do not occur in nature. These are giving rise to some novel applications such as "cloaking" (where photonics can be applied to make things appear invisible in certain parts of the spectrum). Other real possibilities of nanotechnologies are the development of a three-dimensional microchips that would allow major steps forward in processing speed.

Although in principle, photons do not interact with one another in a vacuum, in a medium such as glass, high-intensity laser excitation can cause a non-linear response of the glass medium and cause the photons to interact with one another. Conceptually, this may make possible the development of ultrahigh speed devices, switching as quickly as 1 trillionth of a second. This would make them up to 1000 times faster than current optical devices.

The Centre for Excellence for Ultrahigh-Bandwidth Devices for Optical Systems is recognised as one of the top few photonics research centres in the world. It is a collaboration of eight of Australia's top universities and number of industry participants. Expectations are high that it will make a major contribution in the emerging field of photonics.