That's knot light

Always thought light traveled in a straight line? That’s only when it isn’t being tied in knots. A team of physicists working at the universities of Bristol, Glasgow and Southampton recently did just that.

Under certain conditions, light can be twisted into a helix around its travel axis. In that case, the light along the axis itself is cancelled out, and the light appears to be corkscrewing rather than traveling in a straight line. This twirling light pattern is called an ‘optical vortex’.

Lead author Mark Dennis and his team took this one step further. They used knot theory (a hitherto purely abstract branch of mathematics begun by Lord Kelvin in 1867 and inspired by… well… knots) to design holograms that could direct the flow of light into optical vortex knots.

The researchers are confident that this new laser technology will find wide usage in a variety of industries.

Illustrations: The coloured circle represents the hologram, out of which the knotted optical vortex emerges.