SCIENTISTS at The Australian National University (ANU) have developed a new breed of materials which can twist light at will with possible applications in photonics.
Photonics is widely seen as a light-based successor to electronics. The ANU development of artificial “metamaterials” can rotate the polarisation of light in ways never before seen in natural materials. The polarisation effect can be switched on and off directly using light.
Electronics is estimated to account for two per cent of the global carbon footprint, a figure which photonics has the potential to reduce significantly. Already light carried by fibre optics, has replaced electricity for carrying signals over long distances.
The next step is to develop photonic analogues of electronic computer chips, by actively controlling the properties of light, such as its polarisation.
The ability of a material to rotate polarisation springs from the asymmetry of a molecule. It occurs in natural minerals and substances. Sugar concentrations can be measured via polarisation rotation methods because sugar is asymmetric, for example.
Using metamaterials, photonics researchers can use thin slices of material in place of the bulky collections of lenses and mirrors currently used to create photonic systems.
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 are formed from a pattern of tiny metal shapes, dubbed meta-atoms. To obtain optical rotation Mr Liu and his colleagues used pairs of C-shaped meta-atoms, one suspended above the other by a fine wire. When light is shined on to the pair of meta-atoms the top one rotates, making the system asymmetric.
Because light affects the symmetry of such a system, researchers can tune the material's response simply by shining a light beam on it. Tunability of a metamaterial is an important step towards building devices based on these artificial materials.