Free-space optical could help address spectrum crunch

fiber optical (Pixabay)
Optical fiber requires a physical cable that connects two ends of a link, whereas free-space optical technology is basically doing the same thing but sending signals through the air.

The commercial optical fiber market is a large one compared to the free-space optical market, but the folks at LGS Innovations, a former subsidiary of Alcatel-Lucent, see that changing.

“We’re seeing a lot more interest in commercial free-space optical communications now than we did a few years ago,” Tom Wood, technical director of New Business Development at LGS Innovations, told FierceWirelessTech.

The company has been working in the optical communications and technologies space for more than 20 years, mostly related to government work. Now, the commercial sector is coming around.

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Optical fiber requires a physical flexible cable that connects two ends of the link, whereas free-space optical technology is basically doing the same thing but sending signals through the air. The frequency band used for free-space optical communication is roughly 193 terahertz.

In fact, anybody who’s building a next-generation satellite constellation might want to take a look at optical communications. The folks at LGS are seeing a lot of interest in using free-space optical communication to communicate between satellites and between the ground and satellites. LGS engineers, builds and deploys free-space optical systems used to communicate between satellites and between satellites and their respective ground stations.

In the commercial satellite communications market today, everybody needs spectrum, but it’s congested and there’s a lot of competition for the airwaves. With free-space spectrum, there are fewer limitations and it’s unlicensed, according to LGS representatives who spoke to FierceWirelessTech. In addition, the size, weight and power of the optical terminals can be much smaller than for a comparable RF terminal, and that’s true for both the spacecraft and stations on the ground.

Plus with everybody uploading video and other content to social media sites, capacity becomes more of an issue. “These free-space optical communications systems can support the kind of bandwidth that users are coming to expect,” Wood said.

Jay Moorman, group president of wireless solutions at LGS, said the crowded nature of spectrum is driving alternative solutions, with free-space optics being one of them. It’s also an attractive solution for remote areas where it’s challenging to deploy terrestrial gear.

As for its ability to offer “five 9s” reliability, Wood said that free-space optics doesn’t do well going through clouds and rain, but with multiple ground stations strategically placed, it can provide high reliability. “As far as communications in space, five 9s reliability for this is quite achievable,” he said.

Moorman agreed, adding that it’s not likely that anyone is going to take free-space optics and use it as a replacement for ground-based terrestrial systems anytime soon, but as they push the science, that is more likely to become an achievable goal. “I don’t see it happening in the short term,” he said. “We’re still a little bit a ways from that.”

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