For decades, physicists have known that quantum theory allows for wavelike objects to follow curved trajectories known as Airy functions, after the 19th-century British astronomer George Biddell Airy. Scientists have now managed to bend a beam of light into just such a shape.
Demetri Christodoulides, Aristide Dogariu, and their colleagues at the University of Central Florida in Orlando passed an ordinary, but thick, laser beam through a liquid-crystal screen. The incoming light waves were oscillating in sync, but the orientations of the liquid crystals knocked them out of sync in a predetermined way. So the waves emerging on the other side formed interference patterns—with their peaks and troughs either canceling or reinforcing one another. One main shape veered to one side, tracing a parabola similar to the ballistic trajectory of a cannonball. Similar, but thinner shapes, also part of the Airy function, extended parallel to the main parabola, the team reports in the Nov. 23 Physical Review Letters.
Christodoulides says the curved patterns could help in the manipulation of light and also, because of light’s pressure, of matter. “Maybe we can find ways of sending energy around obstacles … or push particles along curved trajectories,” he says.