Method Bends Beams of Light

Contrary to what we learned in science class, that light beams travel in straight lines, researchers have discovered light can indeed be bent.

The researchers from Tel Aviv University call these rays ‘Airy beams’ after English astronomer Sir George Biddell Airy, who studied the parabolic trajectories of light in rainbows, and were first created at the University of Central Florida.

This is an artist's conception of simultaneous multiple nonlinear generations of Airy beams. (Image: AFTAU)

Now, the fortuitously-named Professor Ady Arie and his graduate students Tal Ellenbogen, Noa Voloch-Bloch, Ayelet Ganany-Padowicz and Ido Dolev of Tel Aviv University's Faculty of Engineering have demonstrated new ways to generate and control Airy beams by employing new algorithms and special nonlinear optical crystals.

Some of these new applications, such as a light source to generate beams that can turn around corners, or lighted spaces that contain no apparent light source, are still five or ten years away, said Arie. But his research has immediate applications as well. For example, because small particles are attracted to the highest intensities of a beam, the pharmaceutical and chemical industries can use the new beam to sort molecules according to size or quality, filtering impurities from drug formulations that might otherwise lead to toxicity and death.

A light that can twist around curves

Until now Airy beams have been generated through ‘linear diffraction’ using tools that project a single color of light through glass plates of varying thicknesses. But using crystals they built in the lab, Tel Aviv University's approach uses another technique: nonlinear optics. Sent through crystals, light waves bounce inside the crystal, changing their wavelength and color. It is through this process, the researchers say, that the door is opened for creating new light beams at new wavelengths with greater control of their trajectories.

"We've found a way to control whether an Airy beam curves to the left or to the right, for example," said Arie. He has also found a way to control the peak intensity location of the beams, which are generated through a nonlinear optical process.

Nonlinear optics is a sub-field of optics that deals with the response of materials to high intensities of light. The strong interaction between light and material results in the generation of new colors, which are half the wavelength of the original input light frequency. For example, a nonlinear response to infrared light can generate visible light, which is how those bright, green "laser pointers," often used in presentations given in large rooms, generate their light.

According to the researchers, Airy beams promise remarkable advances for engineering. They could form the technology behind space-age "light bullets" –– as effective and precise defense technologies for police and the military, but also as a new communications interface between transponders. As tiny, tight packets of information, these Airy beams could be used out in the open air, researchers hope.

For more information, visit: www.aftau.org