Scientists at the Universities of Glasgow, Bristol and Southampton have succeeded in tying knots in light.

The remarkable feat, reported in the latest edition of the journal Nature Physics, was achieved using special holograms which enabled the scientists to bend and control beams of light.

The discovery has applications in precision laser technology, traffic speed radar equipment and laser instruments to measure height.

Prof Miles Padgett, of the Department of Physics at the University of Glasgow, who led the experiment which was based on a theory developed by Dr Mark Dennis of Bristol University, said: “We usually think of light as flowing in straight lines, but it can also be twisted, like a corkscrew, along its axis to create an optical vortex.

“When you do this, the light waves at the axis cancel each other out resulting in the centre of the vortex having a light intensity of zero – in other words there’s no light in the middle, so if you were to shine the light beam on a flat surface, it would appear as a donut-shaped ring of light.

“What we’ve been able to do is tie these vortices together using specially-designed holograms based on mathematical knot theory to guide and control the vortices.”

This research demonstrates a physical application for a branch of mathematics previously considered completely abstract.

Prof Padgett added: “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.”

Knotted vortices were first studied by Lord Kelvin in 1867 during his research into atoms.

For more information contact Stuart Forsyth in the University of Glasgow Media Relations Office on 0141 330 4831 or email s.forsyth@admin.gla.ac.uk

First published: 18 January 2010

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