Twisted Waves Carrying Terabits of Data

BBC News - 'Twisted light' carries 2.5 terabits of data per second

Researchers have clocked light beams made of "twisted" waves carrying 2.5 terabits of data - the capacity of more than 66 DVDs - per second.
The technique relies on manipulating what is known as the orbital angular momentum of the waves.

Recent work suggests that the trick could vastly boost the data-carrying capacity in wi-fi and optical fibres.

The striking demonstration of the approach, reported in Nature Photonics, is likely to lead to even higher rates.
Our planet has "spin angular momentum" [OAM] because it spins on its axis, and "orbital angular momentum" because it is also revolving around the Sun.

Light can have both these types, but the spin version is the far more familiar - as what is commonly called polarisation, or the direction along which light waves wiggle. Polarising sunglasses and many 3D glasses work by passing one polarisation and not another.
Most recently, Bo Thide of the Swedish Institute of Space Physics and a team of colleagues in Italy demonstrated the principle by sending beams made up of two different OAM states across a canal in Venice, an experiment they described in the New Journal of Physics.

BBC News - 'Twisted' waves could boost capacity of wi-fi and TV

In a highly publicised event in 2011, the team used a normal antenna and their modified antenna to send waves of 2.4 GHz - a band used by wi-fi - to send two audio signals within the bandwidth normally required by one. They repeated the experiment later with two television signals.

Encoding many channels on the same frequency through radio vorticity: first experimental test - IOPscience

Fabrizio Tamburini et al 2012 New J. Phys. 14 033001


We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion.