The effect is subtle, but has significant practical applications

Apr 20, 2012 14:40 GMT  ·  By
Light normally travels in straight lines, but with some clever pre-adjustment, it curves instead
   Light normally travels in straight lines, but with some clever pre-adjustment, it curves instead

In a finding that could eventually enable scientists to develop a means of moving objects from a distance by using light, a team of experts was recently able to demonstrate that light can bend while traveling, without external influences.

Physics students learn that light always travels in a straight line, but there are exceptions to this rule. In deep space, huge gravitational centers distort the path of light, bending it around very heavy structures. When a light beam enters water, its direction changes abruptly as well.

But these deviations are produced by external causes – gravity and the refractive index. What experts at the Technion, Israel Institute of Technology, in Haifa, demonstrated was that light sources can be fashioned in such a way as to emit a bent stream of photons.

Light therefore travels in a curve without any external influence. Weirdly enough, this was first demonstrated in the late 1970s by Bristol University physicist Michael Berry and colleague Nandor Balazs, at the State University of New York, Stony Brook.

Until 2007, this discovery was largely ignored. But 5 years ago University of Central Florida expert Demetri Christodoulides demonstrated that the so-called Airy waveform function– which described how quantum particles move – can be created and manipulated using lasers.

Building on this foundation, the IIT group, coordinated by physicist Mordechai Segev, now proposes that light can be made to bend at any angle. The researchers say that it can even be made to travel in a circle, Science Now reports.

The Airy function is complex, but intuitive. To understand it, it is important to know that a beam of light is made up of waves, each of which is an alternating procession of waves and troughs. When a peak and a trough meet up, they produce darkness because they cancel each other out.

But when a peak passes another peak, a process called constructive interference occurs, producing a brighter spot. In order to create Airy waveforms, experts need to control the initial position of peaks in all waves being emitted by a laser.

Details of the research appear in the latest issue of the esteemed journal Physical Review Letters.

This study could contribute to the development of advanced optical tweezers, and set the foundation for new manufacturing techniques, where lasers would be able to cut curved holes through solid objects.