'Twisted' light--a new path for wireless communications.
A team of scientists based in the UK, Germany, New Zealand and Canada have taken an important step towards using 'twisted' light as a form of wireless, high-capacity data transmission which could make fibre-optics obsolete.
Scientists can 'twist' photons--individual particles of light--by passing them through a special type of hologram, similar to that on a credit card, giving the photons a twist known as optical angular momentum.
While conventional digital communications use photons as ones and zeroes to carry information, the number of intertwined twists in the photons allows them to carry additional data--something akin to adding letters alongside the ones and zeroes. The ability of twisted photons to carry additional information means that optical angular momentum has the potential to create much higher-bandwidth communications technology.
"In an age where our global data consumption is growing at an exponential rate, there is mounting pressure to discover new methods of information carrying that can keep up with the huge uptake in data across the world," says Dr Martin Lavery, head of the Structured Photonics Research Group at University of Glasgow.
While optical angular momentum techniques have already been used to transmit data across cables, transmitting twisted light across open spaces has been significantly more challenging for scientists to date. Even simple changes in atmospheric pressures across open spaces can scatter light beams and cause the spin information to be lost.
Conducting field tests in a real urban environment in Erlangen, Germany, has revealed exciting new challenges that must be overcome before systems can be made commercially available. Previous studies had indicated the potential feasibility of OAM communication systems, but had not fully characterised the effects of turbulent air on the phase of the structured light propagating over links of this length.
The turbulent atmosphere used in this experiment highlighted the fragility of shaped phase fronts, particularly for those that would be integral to high-bandwidth data transfers. This study indicated the challenges future adaptive optical systems will be required to resolve. "However, with these new developments, we are confident that we can now re-think our approaches to channel modelling and the requirement it places on adaptive optics systems. We are getting ever closer to developing OAM communications that can be deployed in a real urban setting," added Lavery.
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|Date:||Dec 1, 2017|
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