Physicists from the Technion-Israel Institute of Technology and the University of Central Florida have observed the branched flow of light for the first time. Instead of producing completely random speckle patterns, the slowly varying disordered potential gives rise to focus filaments that divide to form a pattern resembling the branches of a tree or the streams of a river delta. This phenomenon is called branched flow. Researchers have achieved a long theorized but never-before-seen like this phenomenon. Researchers shone a laser beam along with the curved film of a soap bubble. They observed that the light travelled and split into filaments, the variations in the bubble’s thickness creating the branched flow phenomenon.
The flow of light changes as it passes through different media, in the same way, refraction occurs when you submerge an object in the water.
To create the branching-flow effect with light, the structure of the medium – in this case, the soap bubble – needs to be somewhat random in nature, and the physical, spatial variations within the structure to be larger than the wavelength of the light flow itself. Micro disturbances across the bubble’s surface scatter the flow of light, splitting it into streams like a river delta, which then further split and so on. For the best results, making soap bubbles the perfect candidate.
To guarantee a high level of accuracy, the researchers inserted a fiber-optic cable into the soap-bubble membrane.
The team tested the soap-bubble laser technique on both stable and moving membranes by restricting the airflow around the bubbles, allowing them to witness the full beauty of white light splitting into multiple thicknesses and colours in their artificial “light delta.”
“The fact that we observe it with light waves opens remarkable new possibilities for research."
The team’s paper was published on July 1, 2020