New breed 'metamaterials' can put twist in light

Scientists have created a latest breed of materials known as metamaterials that can twist the light.

Mingkai Liu, a PhD student at the ANU Research School of Physics and Engineering (RSPE), said that this new material can rotate lights polarization, orders of magnitude more strongly than natural materials and they can switch the effect on and off directly with light.

It would be the latest step in the development of photonics, the faster, and more compact and less carbon-hungry successor to electronics. This random find in the washing basket led the team to create these artificial materials that showed extraordinary properties quite unlike natural materials.

The ability of a material to rotate polarisation, as in this experiment, springs from the asymmetry of a molecule. It occurs in natural minerals and substances; for example, sugar is asymmetric and so polarisation rotation can be used to measure sugar concentrations, which would be useful in diabetes research.

Dr David Powell, from RSPE, suggested that the remarkable properties of this artificial material might first be put to use in the budding photonics industry and thin slices of these materials could replace bulky collections of lenses and mirrors, so this miniaturisation could lead to the creation of more compact opto-electronic devices, such as a light-based version of the electronic transistor.

The metamaterials were formed from a pattern of tiny metal shapes, dubbed meta-atoms. To obtain optical rotation the researchers used pairs of C-shaped meta-atoms, one suspended above the other by a fine wire. When light was shined on to the pair of meta-atoms the top one rotated, making the system asymmetric.