Wits U leads in optics

Wits Structured Light Research has been selected as one of the world’s top 30 advances in the filed by Optics and Photonics News on behalf of Optica (formerly the Optical Society of America) and selected as the cover image for the magazine’s announcement in the December 2023 issue.

In February 2023, Wits researchers, led by Professor Andrew Forbes of the Wits School of Physics, announced a new approach to studying complex light in complex systems, such as transporting classical and quantum light through optical fibre, underwater channels, living tissue and other highly aberrated systems. Using atmospheric turbulence as an example, they showed that there are special forms of light that emerge undistorted, while other forms of structured light are unrecognisable. 

Their research was published in Advanced Photonics – the flagship journal of SPIE, the international society for optics and photonics and made international news. They followed this with a communications test showing near error-free data transmission even through very noisy channels. Published in Laser & Photonics Reviews, the team used a new invariant property of vectorial light to encode information. 

This quantity, which the team call “vectorness”, scales from 0 to 1 and remains unchanged when passing through a noisy channel. The team used the invariance to partition the 0 to 1 vectorness range into more than 50 parts (0, 0.02, 0.04 and so on up to 1) for a 50-letter alphabet, a new state of the art process. Because the channel over which the information is sent does not distort the vectorness, both sender and received will always agree on the value, hence allowing for noise-free information transfer. 

“What is exciting about the work is that it opens up a new approach to studying complex light in complex systems, for instance, in transporting classical and quantum light through optical fibre, underwater channels, living tissue and other highly aberrated systems,” says Forbes.  “We have always maintained the “patterns of light” are the answer to communicating fast and securely; now we know how to select patterns that pass through highly distorting media as if the media was distortion-free.

“Maintaining the integrity of structured light in complex media will pave the way to future work in imaging and communicating through noisy channels, particularly relevant when the structured forms of light are fragile quantum states.”