With the opening of Australia's first nanoscience research centre in April, Professor Ben Eggleton, leader of the Nanoscale Photonic Circuits Programme at the University of Sydney, and director of the Australian Research Council Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), discusses the centre’s activities in developing photonics integrated circuits
The 21st century will be the century of photonics and nanotechnology – nanophotonics – which deals the study of the behaviour of light on the nanometre scale, and of the interaction of nanometre-scale objects with light.
The new Australian Institute for Nanoscale Science and Technology (AINST) at the University of Sydney will ensure that Australia is at the forefront of this new domain of nanophotonics. Researchers at the institute are already working on new technologies including light-powered chips for computers and smartphones, unhackable communication using individual photons of light, and high capacity wireless networks using microwave photonic processors on silicon chips.
They’re building on strong foundations. The Australian photonics ecosystem is healthy, with a track record in creating and commercialising photonics technologies that have been widely deployed in telecommunications networks around the world, and are now being developed for applications in healthcare and security.
Collaborations between Australian universities and companies such as Finisar Australia have created new products and significant new business opportunities that are employing our graduates.
Now, a new entrepreneurial culture is translating our research into real world outcomes through various spin-off companies that have been formed or are being incubated, such as Miriad Technologies from the University of Sydney and Hotlight Systems from the ANU.
Now, nanophotonics has a new national home, with the opening in April of the $150 million Sydney Nanoscience Hub, headquarters for the Australian Institute for Nanoscale Science and Technology. The Hub has a remarkable suite of facilities that enables researchers to take their ideas from the laboratory and rapidly develop and test them, including:
- Floating research laboratory floors built on a concrete slab that is decoupled from the walls, to create an incredibly stable environment with low vibrations for high-precision measurements;
- Electromagnetic shielding in research laboratories designed to suppress unwanted interference from outside the lab; and
- Special air conditioning in the research laboratories designed to keep room temperatures stable to within 0.1 degree by replacing all air in the room once every minute.
The co-location of labs with the clean room facility will ensure we have a close loop for designing, fabricating and characterising nanophotonics devices, which has not been possible. The combination of the specially designed laboratories with the clean room facility that will house an end-to-end nanolithography facility is unique in Australia. The facility will also provide prototyping capabilities that will allow researchers to create robust prototypes that can be evaluated by end-users and form the basis of new commercialisation opportunities. The Sydney Nanoscience Hub will bring together leading edge researchers with industry and end-users in an entrepreneurial space that will inspire students and early career researchers.
The evolution of photonics
Researchers brought together at the new Hub are already working on a new optical processing technology based on nanophotonics. This research is being undertaken by the CUDOS ARC Centre of Excellence, which is headquartered at the Sydney Nanoscience Hub at the University of Sydney with nodes at ANU, RMIT University, Macquarie University, Monash University, Swinburne University and UTS.
At CUDOS, we want to take the next step in the evolution of this technology. We want to build a truly photonic chip that will essentially put the entire optical network on to a chip the size of a thumbnail.
By doing this, we can leverage the massive semiconductor industry to harness the processing power of light on a length scale that can be mass produced and integrated into smart devices.
Fortunately, silicon – which is the basis of microelectronics – is compatible with photonics. Most silicon chips today, such as the one in a computer and smartphone, use electrons to transmit information and perform computations. The trick has been getting these chips to work with light as well as electrons.
We now can build photonic circuits into the same silicon, although we are not talking about replacing the transistors in conventional chips with optical transistors. Photonics complements and interfaces with electronics.
How nanophotonics can combine with microprocessors
Photonic chips, or photonic integrated circuits (PICs), represent a new paradigm in information processing. Over the past decade, CUDOS and other researchers around the world have created PICs for a range of applications spanning communications, computing, defence and security, medicine and sensing.
In communication systems, photonic chips can increase the capacity of our communications networks. In data centres, they are reducing the energy consumption, which matters because every Google search today consumes the energy required to boil a cup of water.
In defence, photonic chips can enhance radar technology that helps protect our assets and personnel. And in health, we can reduce the scale and complexity of medical devices that are used to diagnose disease.
Another benefit is in ‘switching’, which is central to all communications networks. At the new Sydney Nanoscience Hub, we are building nanoscale switching technologies that can switch at the speed of light, thousands of times faster than current switching technology.
We are using state of the art lithography, such as the tools in the Nanoscience Hub’s clean room, to fabricate nanoscale circuits and structures. Lithography literally means printing, but in this context we are printing circuits on silicon wafers with nanometre scale features.
So what’s next? We need to transform PICs into active devices that sense and interact, analyse, respond to and manipulate their environment.
We are already building photonic spectroscopy techniques into the same silicon chip that performs electronic processing in smartphones. This will potentially enable smartphones to perform tasks such as medical diagnosis, including analysing blood or saliva, or sense pollutants in the environment via spectroscopy technologies.
But photonics is not well suited to some of these tasks.
So we need moving parts that can manipulate the microscopic world; we need mechanical actuation at the nanoscale, and we really would prefer a chip with no moving parts.
Our approach is to use sound waves that can be generated on the chip. These are not the traditional sound waves that we hear or use in ultrasound, but ultrahigh frequency sound waves. We refer to them as ‘phonons’, which are particles of sound, just as photons are particles of light.
We are talking about hypersound, phonons with frequencies from 100 megahertz to tens of gigahertz. We are building a completely new chip that incorporates a photonic circuit for these hypersound phonons.
Harnessing hypersound on a chip enables the manipulation of microscale biological and chemical elements, which means we can mix, sort and select and even create a centrifuge on a chip. This is a laboratory-on-a-chip that can be integrated into the smartphone.
This represents a new paradigm for information processing. The speed of sound is about 100,000 times slower than the speed of light. We can couple information from the light wave to hypersound and store information.
The phonon frequencies coincide with the radio frequencies that are important in next generation mobile communications and radar, which allows us to process these microwave waves via the interaction between optical and phonon waves.
Australia has always punched well above its weight in photonics research and commercialisation. We now have the nanoscience and nanotechnology infrastructure and capacity to take the next big step, which is to bring photonics on to the chip where it will transform our lives.