Wits University using lasers to deliver high-speed Internet connections

A team of researchers at Wits University recently developed a free-space optical (FSO) solution for Internet connectivity, which could bridge the digital divide in Africa.

The technology is based in the field of photonics, which concerns the properties of light generation and the transmission of information through light via manipulation.

Fibre optic cables also lie in the realm of photonics, as they transmit data by emitting and receiving light over a glass core medium.

The FSO solution developed by the Wits team functions like a laser, transmitting a focussed beam of light to a receiver through the air.

MyBroadband spoke to Professor Andrew Forbes from the Wits School of Physics about how the technology works and its potential applications.

Forbes heads up the team which has developed the FSO solution.

Wits FSO Team


FSO and photonics

Forbes said that transmitting data using light is far faster than using conventional Wi-Fi.

“Our FSO solution is based on optical frequencies, which are many orders of magnitude faster than radio. So this means faster speeds,” he said.

He explained that the information transmitted over the beam of light was secured using quantum technology developed by the team.

“Our classical technology is based on using patterns of light as a means to introduce extra channels and our quantum technology is based on single photons and entangled photons,” said Forbes.

While faster than Wi-Fi, free-space optics have notable disadvantages which prevent it being implemented in the same manner.

“The disadvantage is that distance links are limited to a few kilometres in horizontal paths. Also, the line of sight must be clear – no obstacles,” said Forbes.

It is very fast, however, with the current technology theoretically capable of transmitting up to 10Gbps.

“We believe we can push it to 10Gbps using four patterns of light rather than just one. In principle, this can be unlimited if we can get more patterns to work.”

Wits FSO 2


Implementations

Forbes said the Wits team recently signed an agreement with PARSEC to improve its FSO platform using their technology.

“We have just signed an agreement with PARSEC to take their platform for FSO and make it faster using our classical technologies and fundamentally secure using our quantum technologies.”

He said the real-world implementation of FSO, though, would depend greatly on the particular use-case.

“We believe that it is a case of horses for courses. You wouldn’t want it everywhere, and certainly a fast high-bandwidth fibre backbone is critical,” he said.

“But one could see FSO used to link remote sites and in strategic sites.”

An example of a site which would benefit from an FSO link is the Square Kilometre Array.

The massive radio telescope will require high-speed connectivity, but with no radio interference, so it would not be able to use Wi-Fi.

Forbes added that FSO links could also be used in urban areas to link important buildings, such as banks. Other industries which would benefit from FSO links include stock trading.

According to a report published in Nature, Wall Street traders have started using optical links over standard fibre due to the decreased latency.

The difference between the speed of light as it moves within a fibre optic glass core and as it moves through the air can reportedly have a major effect on automated trading algorithms.

Research in the field of free-space optical links is ongoing, and Forbes said researchers are working to mitigate the disadvantages of the technology.

“The obstruction issue is something we are working on and have just shown transmission through obstacles using special patterns of light,” he said.


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Wits University using lasers to deliver high-speed Internet connections