Light Squeezed Even Tighter

Scientists have proved that light can be squeezed into much tighter spaces than previously thought possible, a breakthrough that could change the world’s thinking on light’s capabilities.

Dr. Shahraam Afshar, research fellow with the Institute for Photonics & Advanced Sensing, University of Adelaide. Afshar theorized that light could be squeezed into much tighter spaces than was previously believed possible – theories that have now been proved. (Photos by Jennie Groom)

The researchers in the University of Adelaide’s new Institute for Photonics & Advanced Sensing (IPAS) made the discovery using optical fibers. These fibers usually act as pipes for light, with the light bouncing around inside the pipe. As the size of the fiber shrinks, the light becomes more and more confined, too, until the ultimate limit is reached and light cannot be squeezed any smaller.

This ultimate point occurs when the strand of glass is just a few hundred nanometers in diameter, about one-thousandth the size of a human hair. If you go smaller than this, light begins to spread out again.

The Adelaide researchers, led by IPAS research fellow Dr. Shahraam Afshar, discovered they now have the potential to push beyond that limit by at least a factor of two.

A researcher tests an optical fiber system in the Institute for Photonics & Advanced Sensing, University of Adelaide.

They can do this due to new breakthroughs in the theoretical understanding of how light behaves at the nanoscale, and thanks to the use of a new generation of nanoscale optical fibers being developed at the institute.

“By being able to use our optical fibers as sensors – rather than just using them as pipes to transmit light – we can develop tools that, for example, could easily detect the presence of a flu virus at an airport; could help IVF [in vitro fertilization] specialists to determine which egg should be chosen for fertilization; could gauge the safety of drinking water; or could alert maintenance crews to corrosion occurring in the structure of an aircraft,” said professor Tanya Monro, Federation Fellow at the University of Adelaide and director of IPAS.

Monro said Dr. Afshar’s discovery is “a fundamental breakthrough in the science of light.”

Another IPAS researcher, Dr. Yinlan Ruan, recently created what is thought to be the world’s smallest hole inside an optical fiber just 25 nm in diameter.

Professor Tanya Monro is director of the Institute for Photonics & Advanced Sensing, University of Adelaide.

“These breakthroughs feed directly into our applied work to develop nanoscale sensors, and they are perfect examples of the culture of research excellence that exists among our team members,” Monro said. “They will enable us to study the applications of light at much smaller scales than we’ve ever thought possible. It will help us to better understand and probe our world in ever smaller dimensions.”

This discovery is expected to lead to more efficient tools for optical data processing in telecommunications networks and optical computing, as well as new light sources.

The announcement of the discovery comes as the IPAS receives its official launch this week.

The Australian and South Australian governments, Defence Science & Technology Organisation (DSTO), Defence SA and the university have committed a combined total of more than $38 million to supporting the establishment of the new institute, which is developing unique lasers, optical fibers and sensors. It also has a strong focus of collaborating with other fields of research to find solutions to a range of problems.

For more information, visit: www.adelaide.edu.au