Echo-less light observed for first time

A team of researchers from the ARC Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) has created special states of light that have no echo.

CUDOS director, the University of Sydney’s Professor Benjamin Eggleton, said this was the first time the phenomenon had been observed since it was first proposed nearly 70 years ago.

The team developed a method that allows waves of light to travel through complex scattering objects and have the entire wave arrive at once at its point of destination.

The research, published this week in Nature Photonics, could have applications in many areas: “For example, using light waves that do not have an echo would increase the depth that medical imaging devices can capture in human tissue, which could increasing the early detection of tumours and disease,” Professor Eggleton said.

A senior researcher on this project, Professor Eggleton also noted that although the researchers used light, it was also applicable to other waves such as Wi-Fi, sound waves, radio and mobile phones.

“Essentially, this could be applied to any application whereby you want the entire wave to arrive at the other end at the same time so your signal doesn’t get garbled by echoes,” he said.

Former postdoctoral researchers from the University of Sydney who were involved include Dr Jochen Schroeder, now a senior lecturer with RMIT, who led the project, and Dr Joel Carpenter, now a lecturer at the University of Queensland, who designed and performed the experiments.

Read more in the New Scientist report on the paper, ‘Observation of Eisenbud-Wigner-Smith states as principal modes in multimode fibre’.