Researchers have developed a technique enabling light waves to pass through an object and arrive simultaneously at the other end, in a scientific advance six decades in the making.
RMIT’s Dr Jochen Schroeder led a team of researchers at the Centre for Ultrahigh Bandwidth Devices for Optical Systems on the pioneering project that demonstrated a phenomenon first proposed in 1948, but which had never before been observed experimentally.
The research has been published in the international journal Nature Photonics.
Creating special states of light that have no echoes, the team developed a method that enables an entire wave of light, sound or radio to travel through complex scattering objects and arrive at its point of destination, echo-free.
“The ability to make light pass through an object and arrive all at once at the other end is important in many fields,” said Schroeder, a senior lecturer in the School of Electrical and Computer Engineering.
“For example, the scattering of light in biological tissue such as skin or brain limits the depth that can be imaged.
“Techniques such as these mitigate this scattering and allow imaging of depths inside tissue which would not otherwise be possible.”
Dr Joel Carpenter, a lecturer at the University of Queensland who designed and performed the experiments, likened the waves of light to yelling a message to a friend at the end of a tunnel.
“Because of the way the sound waves bounce off walls and other objects the message your friend receives will be distorted by echoes and they might not be able to understand you,” he said.
“Now imagine you had a specially shaped horn or speaker that launched your voice into the tunnel in a particular shape so that somehow no echoes arrive at the other end.
“We’ve demonstrated the same idea, except using light bouncing around inside an optical fibre.”
The new phenomenon was demonstrated using light waves in optical fibres by precisely measuring the way light travels through the fibre in space and time.
The researchers then worked out what laser beam shapes would travel through without echoes, generated beams of those shapes, and put them into the fibre, before confirming that all the light arrives simultaneously at the other end.
The technique is applicable to other waves such as sounds waves, WiFi, radio and mobile phone – any applications where it is critical for entire waves to arrive together to ensure signals are not garbled by echoes.
Story: Gosia Kaszubska