Technion-Israel Institute of Technology researchers have conducted the first experimental observation of the branched flow of spatially incoherent light by using liquid dish soap. The study has been published in the journal Physical Review X. Scientists described their experiments involving shining light on 2D samples of liquid dish soap and their observations.
Previous research has shown that light moving through a disordered media can lead to branching. Some amount of a beam can take one path around an object while another part of the same beam can take another path. Such branching can lead to channels of light moving through a given medium. Here, scientists used liquid dish soap as the medium.
They applied liquid dish soap to a plate of glass and then shined a light through it from a side edge. They took pictures from above as the light moved through the soap toward the opposite edge. Researchers added some dye that grew brighter as it was struck by light, to enhance the action.
Scientists were able to observe the light initially strike a dense portion of the soap, then split and create two channels. They split and so on and on until the light reached the opposite edge, as the light in the two channels struck other dense parts of the soap. They said the effect was similar to a lightning strike or even the form of a river delta.
Scientists noted that the flow of light can travel in any direction. It allowed the light to also travel up toward the camera. They also conducted an experiment that involved testing what happened when some of the light coalesced after splitting. Some of them was in sync. They were able to see that in areas where the light was in sync, by adjusting the light source.