Optics researchers at the University of Queensland and Nokia Bell Labs in the United States have developed a new technique to demonstrate the reversal of optical waves over time, which could transform the fields of advanced biomedical imaging and telecommunications.
The reversal of waves in physics does not mean the journey back to the future; describes a special type of wave that can retract a path back through an object, as if it were watching a traveling wave film, played backwards.
Dr. Mickael Mounaix and Dr. Joel Carpenter, together with Dr. Nick Fontaine from Nokia Bell Labs, are the first to demonstrate this time the reversal of optical waves, using a new device they have developed that allows complete control. of 3-D light through an optical fiber.
“Imagine emitting a short pulse of light from a small point through scattered material, such as fog,” said Dr. Mounaix.
“Light begins in one place in space and in one moment in time, but it becomes scattered as it travels through the fog and reaches the other side in many different locations, at many different times.
“We found a way to accurately measure where all that scattered light goes and at what times, then we create a ‘back’ version of that light and send it back through the fog.
“This new wave of light reversed in time will resume the original scattering process, as if you were watching a movie in reverse – eventually reaching the source right at the beginning: a single position at a single moment in time.”
Dr. Carpenter said that the reverse version of the light beam, known as the time-reversed wave, was a three-dimensional object with a random appearance, like a small cloud of light.
“To create that cloud of light, you have to take an initial ball of light flying into the system and then carve it into the 3D structure you want,” Dr. Carpenter said.
“Sculpting has to take place on trillion-second time scales, so it’s too fast to sculpt using any moving parts or electrical signals – think of it as shooting a high-speed clay ball through a static device without moving parts, which slices the ball, deflects the pieces and then recombines the pieces to produce an exit sculpture, all while the clay flies without ever slowing down.
Dr. Fontaine said there is no device that can fully control and form a 3-D light beam before the team develops this technique.
“It is very important to control the delivery of light as accurately as possible for many applications, from imaging to capturing objects with light, to creating very intense laser beams,” said Dr. Fontaine.
Using the new device, researchers will be able to perform experiments that were previously impossible, testing theoretical concepts in many fields.
This research was published in Communications about nature.
Fog laser cutting
Mickael Mounaix et al. Time-reversed optical waves by the arbitrary generation of a vector space-time field, Communications about nature (2020). DOI: 10.1038 / s41467-020-19601-3
Provided by the University of Queensland
Citation: Physicists create time-reversed optical waves (2020, December 14) retrieved December 15, 2020 from https://phys.org/news/2020-12-physicists-time-reversed-optical.html
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