The new class of laser beam does not follow the general rules of refraction


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Researchers in Central Florida have developed a new type of laser beam that does not follow long-held theories about refraction and travel of light.


Findings, which were recently published Nature photonics, Can have enormous implications for optical communications and laser technologies.

“This new class of laser beams has unique properties not shared by common laser beams,” says Ayman Abordi, a professor at UCF’s College of Optics and Photonics and principal investigator of the study.

Beams known as spacetime wave packets, when they are refracted, follow different rules. Normally, when it travels in a dense material, the light slows down.

“Conversely, spacetime wave packets can be arranged to behave in a normal way, to not change the speed at all, or even to speed up in dense material,” says Abordy . “As such, these pulses of light can reach different points in space at the same time.”

“Think about how a spoon inside a glass filled with water looks broken at the point where water and air meet,” says Abordy. “The speed of light in the air varies from the speed of light in water. And so, the light rays begin to bend after the air crosses the surface between the water, and so clearly the spoon looks bent. It’s a good Well known. The event described by Snell’s Rule. ”

Although Snell’s law still applies, the inherent change in the velocity of pulses is no longer applicable to new laser beams, says Abordy. These qualifications are counter to the principle of the format that light always travels as if it takes the shortest route, he says.

“What we find here, however, is that no matter how different the material is that light passes through, there always exists one of our spacetime wave packets that can traverse the interfaces of two materials without changing their velocity Is, ”says Abordi. “So, no matter what the properties of the medium are, it will go across the interface and continue as if it is not.”

For communication, this means that the speed of the message traveling in these packets is no longer affected by traveling through different materials of different densities.

“If you’re trying to communicate about two aircraft at the same depth with two submarines, but one is farther away and closer to the other, the one that is farther away will be delayed longer than that,” says Abordi . “We find that we can arrange for our pulses to propagate in such a way that they arrive in two submarines at the same time. In fact, now the person sending the pulse does not even need to know where the submarine is. , As long as they are at the same depth. All those submarines will receive a pulse at the same time so that you can synchronize them blindly where they know where they are. ”

Abordi’s research team created a spacetime wave packet using a device known as a spatial light modulator to reorganize the energy of a pulse of light so that its properties do not differ in space and time. This allows them to control the “group velocity” of the pulse of light, which is approximately the speed at which the peak of the pulse travels.

Previous work demonstrates the team’s ability to control the group velocity of spacetime wave packets, including optical materials. The present study conducted on that discovery also controlled the spacetime wave packet speed through various media. It is not opposed to special relativism in any way, as it applies to the propagation of the pulse peak rather than to the underlying oscillations of the light wave.

“This new field that we are developing is a new concept for light rays,” says Abordy. “As a result, everything we see when we use these beams reveals new behavior. The behavior we know about light is actually an implicit assumption that its properties are detachable in space and time . Therefore, we all know that optics is grounded. It is an inherent assumption. It is taken as a natural state of affairs. But now, breaking that underlying assumption, we are starting to see new behavior everywhere. Huh. ”

The study was co-authored with Basanta Bhaduri, lead author and former research scientist at UCF’s College of Optics and Photonics, now with Bruker Nano Surface in California and Murat Yasenov, a doctoral candidate at the college.

Bhaduri became interested in Abordi’s research after reading about it in magazines, such as Optics Express And Nature photonics, And in 2018 joined the research team of the professor. For the study, he helped develop the concept and design the experiments, as well as make measurements and analyze the data.

He says the study results are important in many ways, including new research avenues.

“Space-time refraction defies our expectations from the theory of format and provides new opportunities to shield the flow of light and other waves,” says Bhaduri.

Yesenov’s roles included data analysis, derivation, and simulation. They say they want to know more about the work that entangles, which is in quantum systems when two well-separated objects still have an interconnection.

“We believe that the spacetime wave packets have more to offer and can be unveiled using many more interesting effects,” Ysenov says.

Abordi states that the next stages of research include studying the interactions of these new laser beams such as those with laser cavities and optical fibers, in addition to applying these new insights to matter rather than light waves.


Researchers have developed a way to control the speed of light, send it backwards


more information:
Basanta Bhaduri, anomalous refraction of optical spacetime wave packets, Nature photonics (2020). DOI: 10.1038 / s41566-020-0645-6

Provided by the University of Central Florida

Quotes: The new class of laser beam does not follow the general rules of refraction (2020, 6 August) from 6 August 2020 https://phys.org/news/2020-08-class-laser-doesnt-laws-refraction.html

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