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Friday, 28 June 2019

Researchers have discovered the new property of Light: the autotorque

Like a screw with a heterogeneous thread, the light with autotorque will have immediate technological applications. [Image: Rego et al. - 10.1126 / science.aaw9486]

Twisted light

Spanish researchers have discovered that light has a new property, which they named autotorque.

This discovery opens up exciting possibilities in light-related applications, from consumer appliances to scientific equipment and fiber-optic telecommunications.

In addition to the many known properties - such as intensity and wavelength - the light can be twisted , possessing what is known as angular momentum - the photons travel in a straight line, but spinning around the axis of the beam of light.

Light beams carrying highly structured angular momentum, known as angular orbital momentum (OAM), are known as vortex bundles.

The intensity of these beams, which have a ring-like shape, has applications in optical communications, microscopy, quantum optics and microparticle manipulation.

Vision of longitudinal section of light beam with autotorque. [Image: Rego et al. - 10.1126 / science.aaw9486]

Light with autotorque

Knowing this turn of twisted light, Laura Rego and colleagues at the University of Salamanca wondered if this spin of the photons could not function in a time-dependent way.

It can, and this is precisely what the autotorque consists of: Light beams with their own torque have an angular momentum that changes continuously in time. In other words, light not only twists, but has a different degree of twisting along the length of the beam.

The bundles resemble a croissant, containing more than one octave of orbital angular momentum values ​​along the light pulse.

"This is the first time someone has predicted or even observed this new property of light," said Laura. "For example, we think that we can modulate the orbital angular momentum of light in the same way that frequency is modulated in communications."

If this is indeed possible, telecommunications will be able to jump-start, allowing much more data to be placed on the same optical fibers.

In addition, this new light mode opens new perspectives for optical tweezers , tiny tracers used to trap nanoparticles in cells.


Generation of extreme-ultraviolet beams with time-varying orbital angular momentum

 Laura Rego, Kevin M. Dorney, Nathan J. Brooks, Quynh L. Nguyen, Chen-Ting Liao, Julio San Roman, David E. Couch, Allison Liu, Emilio Pisanty, Maciej Lewenstein, Luis Plaja, Henry C. Kapteyn, Margaret M. Murnane, Carlos Hernández-García

 Science DOI: 10.1126 / science.aaw9486

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