Freezing An Optical Fiber Makes Light And Sound Interact 1,000 Times More Strongly

[Tia91]

Researchers from the Max Planck Institute for the Science of Light, Leibniz University Hannover, and the Leibniz Institute for Photonic Technologies have found that freezing the liquid core of a specialized optical fiber creates an extreme environment where light and sound waves interact more than a thousand times more strongly than they do inside a standard fiber. The team used liquid nitrogen to cool the liquid inside these liquid core optical fibers down to negative 196 degrees Celsius, causing the material at the center to transition from liquid into a solid.

What genuinely surprised the researchers is that freezing the core did not stop the fiber from carrying light at all. Both the still liquid section and the newly frozen section of the fiber kept guiding light normally, and remarkably both sections also turned out to guide hypersonic sound waves as well, opening the door to a phenomenon called Brillouin-Mandelstam scattering, where light and sound waves interact and exchange energy with each other inside the material.

That interaction already exists in ordinary optical fibers used across modern telecommunications, but the researchers found that the extremely dense, tightly confined environment created by actually freezing the fiber's core cranked that same interaction up by more than a thousandfold compared to a standard fiber running at room temperature. Using that dramatically amplified effect, the team successfully demonstrated something called optoacoustic memory, a genuinely key building block for photonic neuromorphic computing systems that process information using light rather than conventional electronic circuits.

The underlying trick exploits the enormous difference in speed between light and sound. Information carried by a fast moving light wave can be transferred into a much slower moving sound wave, temporarily held there almost like a tiny physical buffer, and then converted back into light again once it is actually needed, which is a genuinely elegant way to build a working memory element directly out of physics rather than conventional transistor based electronics.

Beyond neuromorphic computing specifically, the research team believes this same frozen fiber platform could open up new possibilities for quantum information processing, microwave photonics, and high precision sensing, since the core breakthrough here is really about achieving an entirely new and easily reproducible physical environment for extreme light and sound coupling rather than a narrow application tied to just one single specific use case

This frozen fiber makes light and sound interact 1,000x more stronglywww.sciencedaily.com