Signals from the future
Photonics, the faster, more compact and less carbon-hungry successor to electronics is a major research area at ANU Research School of Physics and Engineering.
Putting a twist on light
When PhD student Mingkai Liu found a piece of wire in his washing basket, it triggered an idea that led to him developing a new material that could put a twist into light.
His creation is the latest in a new breed of materials known as metamaterials. These artificial materials show extraordinary properties quite unlike natural materials.
"Our material can put a twist into light – that is, rotate its polarisation – orders of magnitude more strongly than natural materials," said lead author Mingkai Liu, a PhD student in the Nonlinear Physics Department area.
The metamaterials are formed from a pattern of tiny metal shapes, dubbed meta-atoms. To obtain optical rotation Mr Liu and his colleagues used pairs of C-shaped meta-atoms, one suspended above the other by a fine wire. When light shines on to the pair of meta-atoms the top one rotates, making the system asymmetric.
"The high responsiveness of the system comes because it is very easy to make something hanging rotate," said Mr Liu.
Impurity makes nanolasers shine
Like Mingkai Liu, Tim Burgess had a bit of serendipity in his PhD project, when he accidentally transformed a normally inactive nanowire into a laser, with a simple impurity.
Doping gallium arsenide with zinc as part of electrical conductivity tests in the Department of Electronic Materials Engineering, he decided to check for light emission too, and found he was on to something.
The nanolasers are one hundredth the diameter of a human hair, and will be crucial to the development of photonic components that could one day supercede today’s electronics. Research group leader Professor Chennupati Jagadish isn't done, though; he believes he can shrink them further.
Helping graphene tough it out
It could even be used for fuel cells based on bacterial interactions found in nature.
The amazing electrical properties of graphene, a layer of carbon a single atom thick, make it a material of choice for futuristic miniature electronic components.
But producing it on a large scale has meant complicated processes with toxic solvents until now: Shannon Notley and Tao Wang of the Applied Maths department have created a designer solvent that simplifies large scale graphene production.
"The combination of strength and electrical properties is as good as anyone’s made before, and it’s stable at very high temperatures," said Associate Professor Notley.
The key was designing a surfactant which not only suspended the graphene, but then crosslinked to form a polymer composite.
To complete the suite of amazing properties, Associate Professor Notley said the composite was also bio-compatible which enabled its use for medical applications such as tiny sensors implanted in the body.
"It could even be used for fuel cells based on bacterial interactions found in nature."
ANU is part of the Australian National Fabrication Facility, hosting $20M worth of nanofabrication equipment, such as electron lithography, ion beams, and epitaxy capabilities.
"We especially like students to use the equipment," says node director Professor Chennupati Jagadish.
"They get trained by expert staff, so it’s a unique opportunity to access multimillion dollar facilities and play with them."
Many of Jagadish’s proteges have turned their skills into commercial successes, especially in Asia; for example Gang Li’s Rainbow Optoelectronics, and Shu Yuan’s Quantum Wafer company.
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