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The new metasurface connects two aspects of light: orbital angular momentum and circular polarization (or spin angular momentum).

Polarization is direction along which light vibrates. In circularly polarized light, the vibration of light traces a circle. Think about orbital angular momentum and circular polarization like the motion of a planet. Circular polarization is the direction in which a planet rotates on its axis while orbital momentum describes how the planet orbits the sun.

The fact that light can even carry orbital momentum is a relatively recent discovery, but it’s this property of light which produces strange new states, such as beams in the shape of corkscrews.

Previous research has used the polarization of light to control the size and shape of these exotic beams but the connection was limited because only certain polarizations could convert to certain orbital momentums.

“We have developed a metasurface which is a new tool to study novel aspects of light,” said senior author Professor Federico Capasso, from the Harvard John A. Paulson School of Engineering and Applied Sciences.

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Category: Science