A team of physicists has demonstrated something once considered impossible by successfully controlling the chaotic behavior of light. The key to the unprecedented breakthrough was using light, something only recently theorized but never demonstrated until now.
Given the increasing use of advanced systems that harness the behavior of light, the researchers behind the process say their work could have a direct impact on computing, energy storage, light harvesting, and signal processing, as well as numerous other cutting-edge technologies.
Controlling the Chaotic Behavior of Light Compared to Predicting the Break in Billiards
Led by physicist Andrea Alù, the Einstein Professor of Physics at the City University of New York (CUNY) Graduate Center and founding director of the Photonics Initiative at the CUNY Advanced Science Research Center, the team said that the idea of controlling the chaotic behavior of light not only seems impossible but has never been done before.
The issue, Alù explains, is the fact that light tends to bounce and scatter in several chaotic ways based on even the slightest variation in the chamber into which the light is injected. It’s a phenomenon the professor says is similar to the seemingly unlimited number of variations in a break of the billiard balls, even though the table is a relatively small and seemingly predictable environment.
“In billiards, tiny variations in the way you launch the cue ball will lead to different patterns of the balls bouncing around the table,” Alù explained. “Light rays operate in a similar way in a chaotic cavity. It becomes difficult to model to predict what will happen because you could run an experiment many times with similar settings, and you’ll get a different response every time.”
The Key to Controlling Light Was Light Itself
To try the impossible, Alù teamed with Xuefeng Jiang, a former postdoctoral researcher in Alù’s lab who is now an assistant professor of Physics at Seton Hall University, and Shixiong Yin, who is currently a graduate student in Alù’s lab. Once assembled, the physicists constructed an open-top stadium-style cavity that was irregular enough to cause the chaotic behavior they were seeking. This was critical, they explain, as the more irregular a cavity, the more chaotic the light patterns will be.
“In a cavity that supports chaotic patterns of light, any single frequency injected into the cavity can excite thousands of light patterns, which is conventionally thought to doom the chances of controlling the optical response,” Jaing said.
Next, the team placed two channels on opposite sides of the open-top cavity where they could inject two opposing streams of light. The theory, they said, was that modulating the intensity and time delay of the opposing inputs of light via two knobs on the outside of the chamber would result in the second beam controlling the chaotic behavior of light from the first beam with nothing but light itself.
The team also placed a camera over the top to monitor the behavior of the initial light signal to make sure their experiment was working. After that, it was time to run their experiments.
Sure enough, and after a little trial and error, the team confirmed that modulating the intensity and time delay of the second light in relation to the first resulted in their system controlling the chaotic behavior of light coming from the first beam.
Detailed in their published research, which appeared in the journal Nature Physics, the physicists say that the magic in their system is a concept known as “reflectionless scattering models,” or RSMs. Like the ability to control light with light, these RSMs had previously existed only theoretically.
“We found at certain frequencies our system can support two independent, overlapping RSMs, which cause all of the light to enter the stadium cavity without reflections back to our channel ports, thus enabling its control,” said Yin.
“We have demonstrated that it is possible to control this chaotic behavior,” added Jaing.
Potential Applications Include Energy Harvesting, Computing, Fiber Optics and More
Although the team’s success was confined to a laboratory setting, they believe the process could be adapted to many practical applications, including on products and systems already commonly used today.
“Our demonstration deals with optical signals within the bandwidth of optical fibers that we use in our daily life,” said Yin, “so this finding paves a new way for better storage, routing, and control of light signals in complex optical platforms.”
Next up, the team says they are not done. In fact, they plan to add more knobs to their light-controlling cavity, “offering more degrees of freedom to unravel further complexities in the behavior of light.”
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.