Thaindian News

London, Jan 18 (IANS) A team of physicists has accomplished a remarkable feat by tying light in knots to understanding how to control it — something that has important implications for laser technology used in a wide range of industries.
The team is made up of physicists working at the universities of Bristol, Glasgow and Southampton.

“In a light beam, the flow of light through space is similar to water flowing in a river,” explained study author Mark Dennis from the University of Bristol.

“Although it often flows in a straight line — out of a torch, laser pointer, etc — light can also flow in whirls and eddies, forming lines in space called ‘optical vortices’.

“Along these lines, or optical vortices, the intensity of the light is zero (black). The light all around us is filled with these dark lines, even though we can’t see them,” he said.

Optical vortices can be created with holograms which direct the flow of light. In this work, the team designed holograms using knot theory - a branch of abstract mathematics inspired by knots that occur in shoelaces and rope.

Using these specially designed holograms they were able to create knots in optical vortices. This new research demonstrates a physical application for a branch of mathematics previously considered completely abstract, says a University of Bristol release.

Said Miles Padgett, professor at Glasgow University who led the experiments: “The sophisticated hologram design required for the experimental demonstration of the knotted light shows advanced optical control, which undoubtedly can be used in future laser devices.”

“The study of knotted vortices was initiated by Lord Kelvin back in 1867 in his quest for an explanation of atoms,” said Dennis, who began to study knotted optical vortices with Sir Michael Berry, professor at Bristol University in 2000.

“This work opens a new chapter in that history,” Dennis added.

These findings appeared this week in Nature Physics.