Encoding enormous amounts of information inside the structure of the light itself to send it over great distances without the need for optical fiber and in total safety with respect to atmospheric perturbations and interceptions: this is the turning point in telecommunications that could be outlined thanks to the new technique for controlling the light published in the journal Nature Photonics by researchers from the Politecnico di Milano together with the Italian Institute of Technology (Iit) and Rice University.
The new technique uses ultra-thin artificial materials, the so-called metasurfaces, computer designed to have properties never seen in nature and made with advanced nanofabrication techniques by the IIT Clean Room Facility group.
In particular, the researchers used a layer of gold a thousand times thinner than a hair in which tiny cross-shaped structures (billions in a square centimeter) are engraved: when the metasurface is illuminated by pulses of laser light, its optical properties they change radically, but only for a very short time, by about one millionth of a millionth of a second.
During this very short time window it is therefore possible to modulate a second beam of light by 'writing' a bit of information into its structure (polarization).
This unprecedented approach could trigger a revolution in telecommunications, as it will allow information to be encoded in a beam of light at very high frequencies (up to one million million hertz) and transmitted safely and reliably into free space.