A novel way of boosting data rates in
optical communication using "twisted light" has been shown to work in optical
fibres.
The light is effectively corkscrew-shaped, and more data can be encoded in differently twisted beams.
The concept had been shown off over "free space" but it remained unclear if it would work in fibres.
Now a team reporting in Science has demonstrated data rates of 1.6 terabits per second over 1km of optical fibre.
This is still short of the "over-the-air" rate of 2.5 Tb/s demonstrated by members of the same team in 2012. But it is a powerful proof of principle for adapting the technique to use with fibres in, for example, data centres.
The idea behind twisted light is based on the fact that photons, the most basic units of light, carry two kinds of momentum - a kind of energy in their movement.
"Spin angular momentum" is better known as polarisation. Photons "wiggle"
along a particular direction, and different polarisations can be separated out
by, for example, polarising sunglasses or 3D glasses.But they also carry what is called orbital angular momentum. This is best explained in analogy to the Earth-Sun system: our planet spinning around its axis manifests spin angular momentum, while the orbital angular momentum is seen in our revolution around the Sun.
"Twisted light" approaches use this orbital angular momentum, essentially encoding more data in varying degrees of twist.
