An international group of scientists has succeeded for the first time in filming light pulses forming a photonic Mach cone, the equivalent of a sonic boom but for light. Thanks to an experimental camera capable of capturing 100 billion frames per second, the incredible feat was only possible.
When a wave emitter moves faster than these waves, the Mach cone is created. These cones are routinely formed by super-sonic jets, but things get a little more complicated when it comes to light. Obviously, nothing moves faster than light in a vacuum, but light moves slower in other materials and this is where it is possible to study these elusive phenomena.
The team, led by Dr. Jinyang Liang and Dr. Lihong Wang, shot brief laser pulses through a sandwiched “source tunnel” between two materials with light moving slower. The pulses are scattered as the light passes through the tunnel, creating wavelets that move at superluminal velocity.
With the results published in Science Advances, the camera recorded a Mach cone matching the theoretical predictions for it. The superluminal pulse is a triangular region dragged through the material ahead. When a subluminal pulse repeated the same experiment, no such pattern was visible.
“We recorded a propagating light-induced photonic Mach cone in real time for the first time,” Dr. Liang told IFLScience. “The newly developed single-shot lossless encoding ultrafast compressed photography (LLE-CUP) captured this dynamic light scattering event at 100 billion frames per second in single camera exposure.”
The team had to design not only the experiment but also the camera, which was purposely built to record it, to snap such a fleeting event. A three-in-one recording system is used by the LLE-CUP. One channel works like a regular camera, while the other two record the dynamic event’s temporal information. Combined, they produce this amazing phenomenon view.
.This observation may seem far from the physics applied, but the technology could be used in many different applications, including observing neurons firing up and imaging how microstructures change in living tissues
“We expect the LLE-CUP technology to find wide-ranging applications in both basic and applied sciences,” added Liang. “Our camera is fast enough to watch neurons fire and picture the’ live traffic’ in the brain. We hope that we can use our system to study neural networks to understand how the brain functions.”