Collin Arocho
21 May 2019

In 1880, Alexander Graham Bell provided the first proof of concept for free-space optics. Using his invention, dubbed the ‘photophone’, he proved that beams of light could carry voice conversation through free space, aka, the air. In 2019, Eindhoven start-up, Aircision, is ready to add their modifications to bring this technology into the future, specifically for the upcoming roll-out of 5G.

Aircision recently announced plans to test their modification to existing free-space optics (FSO) technology, with the ultimate goal of using their solution to bolster the roll-out of 5G. The Eindhoven-based start-up has big plans to upgrade line-of-sight laser beam technology for next-generation telecommunications. Thanks to a partnership between the high-tech business incubator, HightechXL, and CERN, they’re one step closer to putting their product to the test.

FSO is a relatively simple technology. Conceptually, using lasers to send and receive data is like that of optical transmissions using fiber-optic cables. The biggest difference is the medium: air rather than glass. The technology is based on connectivity between FSO units, each consisting of an optical transceiver with a laser transmitter and a receiver to provide bi-directional capability. Current units use a high-power optical source that translates data into laser pulses and sends them through a lens, through the atmosphere to another lens. This lens connects to a high-sensitivity receiver via optical fiber, where the transmitted data can then be processed.

While FSO has been around for quite some time, the technology has never really taken off. Even though light can travel faster through air than glass, the communications infrastructure has centered around more stable options, such as fiber-optic networks and cell towers. This is because, historically, FSO has had some hefty limitations. One of the first drawbacks: in order to successfully relay data, the transmitter and receiver must maintain perfect alignment. If the light beam doesn’t reach the receiver, at just the right angle, the information can be lost.

FSO is key to a fast roll-out of 5G, Aircision believes. “It’s easy to deploy, has very high bandwidth and doesn’t require any additional licenses to operate,” commented COO and co-founder, Martijn Boerkamp (on the right). Credit: Aircision

This also means that beam quality is a crucial factor. Typical light beams, known as Gaussian beams, have major issues of degradation, especially over longer distances. The further the light travels, the more the light particles expand out of the central axis, thus resulting in distortion or signal loss. Similarly, when sending data through free space, objects, as well as atmospheric and weather conditions can play an enormous role in signal quality. Beams of light are easily blocked when something passes in front, meaning that fog, mist and even rain can fatally interrupt transmission.

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Using axicon lenses helps to create Bessel-like beams. These differ from Gaussian in that they maintain the central axis, which is the strongest part of the beam, and can also reconstruct after an obstruction. The result: a more secure connection between the transmitter and receiver. The problem: Bessel-like light beams don’t propagate very far (several meters) and are therefore deemed to be impractical.

Application to 5G

Despite the drawbacks, Aircision proposes to use this centuries-old method as a viable solution for the future information and telecommunications systems. In their claim, they’re getting a little boost from a new innovation: the structured laser beam. This Bessel-like beam is almost non-diffractive, and the central axis only diverges slightly (a few millimeters) over a distance of 200 meters. Additionally, structured laser beams can reconstruct after obstruction and can transmit data at speeds similar to those experienced with fiber-optic systems.

Aircision sees an opportunity for using FSO in next-generation telecommunications. The existing infrastructure is adequate for the current standard of 4G, but as 5G comes closer to fruition, it’s clear that network capacity will no longer be sufficient. In order to accommodate more users, with multiple devices, expecting faster speeds, there’s a dire need for a robust investment into the network infrastructure, but, in terms of time, space, and money, this is going to be very costly.

FSO is key to a fast roll-out of 5G, Aircision believes. “It’s easy to deploy, has very high bandwidth and doesn’t require any additional licenses to operate,” commented COO and co-founder, Martijn Boerkamp, adding, “Construction of new cell towers, or placing new fiber-optics networks is not always feasible, nor is it cost effective. Therefore, FSO has the potential to be really competitive in the coming years.”

There is, however, still some work to be done as this system remains largely unproven. Boerkamp: “Theoretically, our beam can exceed the distances required in 5G, yet our team has not tested beyond 200 meters. We’re optimizing our optical components to generate a beam that can propagate over the distances required by 5G, as well as to stay within the limits of laser power that we use, from both a cost and safety perspective.” Implementation of rooftop FSO testing, in coordination with High Tech Campus Eindhoven, is slated for the summer.