Cloud-inspired way to guide light: Waveguiding mechanisms could offer new ways to see inside the human body

Inspired by the way sunlight passes through clouds, scientists have discovered an entirely new way to control and direct light.

This groundbreaking research, led by physicists at the University of Glasgow, allows light waves to be guided along curved paths tunneled through opaque materials that would normally scatter in all directions. It will be.

The discovery could be applied to future generations of medical imaging technology, giving doctors new ways to see inside the human body.

The research could also be applied to directing heat instead of light, opening up new applications in thermal management in computing systems, or confining particles like neutrons instead of light waves, allowing nuclear technology It may be applicable to

The “waveguiding” effect the research team discovered is similar to a fiber optic cable that transports light through its core using a process called total internal reflection. In an optical fiber, the core is surrounded by a cladding material with a lower index of refraction, which allows light to continue reflecting along the length of the core and be transmitted over long distances with minimal loss.

The researchers’ new waveguiding mechanism relies instead on a very different physical process. Instead, light is transported through a solid core of weakly scattering material and then wrapped in more strongly scattering material.

The contrast between the scattering properties of the materials confines the light to the core, making it possible to guide it with unexpectedly high precision.

The research, described in a new paper published in the journal Nature Physics, was sparked by a discussion about clouds in the lab, said corresponding author Professor Daniele Faccio.

Professor Faccio, who heads the Extreme Light Research Group at the University of Glasgow, said: “Tall cumulus clouds are bright white at the highest point and dark gray at the lowest point because sunlight is scattered through the millions of water droplets contained within the cloud. “Often,” he said. .

“Light decays exponentially as it scatters through the cloud, making it dark at the bottom and reflected at the top, making it white.

“We started thinking about whether we could harness that scattering effect in a controlled way and use it to create paths that guide light through scattering materials.”

The research team used a 3D printer to create a highly scattering, opaque white resin structure with a low-scattering core and began experimenting with guiding light through the structure.

They found that more than 100 times more light could be transmitted through the low-scattering core than structures without it. They introduced the phenomenon in both linear and curved structures showing both effects.

The research team also developed a comprehensive mathematical model to explain the physical process of diffusion underlying the results. Remarkably, this model is very similar to the equations that describe the transport of heat through solid materials. With this crossover, the researchers hope their new technology could have widespread use beyond light.

Professor Faccio, from the university’s School of Physics and Astronomy, said: “It is worth noting that even in established fields like optics, there is always room for fundamental new discoveries. I didn’t expect to be able to do it,” he added. It’s a completely new waveguiding method, but that’s where our experiments led us.

“We’re still learning new tricks about light, in this case discovering that the process has more in common with our understanding of how heat travels than with light. I was surprised.

“This means we can expect to use this technology to find new ways to use light to see inside opaque biological tissues, but it also has applications for guides other than photons. We could create new ways to transport heat through systems, such as cooling computers in data centers or transporting particles such as neutrons, which could find new applications in nuclear power plants, for example. It may be opened. ”

Dr Kevin Mitchell, member of the Extreme Light research group and lead author of the paper, said: “The strength of this paper lies in the comprehensive approach we took to explore the possibility of an entirely new approach to guiding light. there is.

“We started with an important question, demonstrated it experimentally, and then actually proved it rigorously mathematically. Now that we have a strong practical and theoretical foundation, we can translate this into society. We will continue to explore ways to find new ways to use it in the future.

Professor Euan Wright of the University of Arizona also contributed to the research.