Smoke rings resemble vortices produced by laser light
Yevhen Rychko / Alamy Stock Photo
Twisting short pulses from a laser to form a series of donut-shaped vortices provides a way to use light to transmit more information.
We commonly encounter vortices in water and air, but similar spiral structures can also form in light rays. One such structure is the vortex ring. In a vortex ring, light particles (or photons) twist and swirl like air particles do in a smoke ring. Yao Jinping Researchers at the Chinese Academy of Sciences have now discovered a way to pack up to 28 vortex rings into a single laser pulse.
To do so, the team precisely adjusted the light's intensity and fine-tuned another property of the light called phase. Light is an electromagnetic wave, and its phase specifies where each part of the wave is in its repeated up-and-down oscillations. In experiments, the duration of the laser pulse was less than a millionth of a second, but only if researchers gave phase-specific values in certain parts of the pulse could the doughnut-like shape and smoke ring-like shape be created. I was able to give it a swirling feature.
They sent the pulses through a series of lenses, special raised crystals, and a “spatial light modulator” that resembles a miniature projector. By the time it passed through them all and reached the detector, it was shaped like a chain of vortex rings. Yao and her colleagues called this a “space-time vortex array,” and the largest one they created consisted of 28 different vortex rings.
Next, they encoded an image of the institute's logo into a set of vortex ring properties. As a proof of principle, they used a string of 16 vortices to transmit 16,384 pixels, but in the future they could experiment with strings containing 28 vortex rings, allowing short bursts of light to be It would be an efficient way to send a lot of information in bursts.
Howard Milchberg The University of Maryland team pioneered experiments with vortex rings, but said the technique of creating vortices in light has recently become more widely available and has many new potential applications. ing. “This field is exploding, and people are thinking different things about what to do with these structures. [in light]. The ability to communicate information is definitely worth considering,” he says.
Although creating donut swirls from light requires a lot of care and getting all the details right, the researchers said they also provided a kind of recipe for creating many more different swirls in the future. There is. alan wilner at the University of Southern California. “Research groups around the world have been trying to design interesting structured light. They're asking, 'What kind of light can we create?' And this could be part of the toolkit that we need to find,” he says.
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Source: www.newscientist.com
