A Guest Blog from CEO, John Jutila
In the first of a recurring series, we’ve invited our CEO, John Jutila, to share some thoughts on a technological topic of choice. This week, he’ll be discussing the current state of free space optical communication technology, and the practical challenges that have hindered adoption in terrestrial applications.
Terrestrial ‘Free Space Optics’ (FSO) is alive, but perhaps not so well.
FSO is fundamentally the transmission of light beams through the air to communicate from one point to another. FSO systems are easy to install: simply affix one link at point A and another at point B and point them at each other without worrying too much about the path in-between, much like a garage door safety sensor. Since the technology transmits light waves (with high bandwidth possible at infrared wavelengths), no frequency permits (as in RF transmission) or construction permits or ground-breaking (as in cables) are required. What’s not to like?
Over the past 30 or so years, I have witnessed a lot of ‘roadkill’ along the venture highway related to FSO. Laser Communications Inc, a US pioneer funded by Safeguard Scientifics in the late 1980s, went bankrupt followed by a string of other disappointing efforts (JOLT, Airfiber, fSONA, TeraBeam, LightPointe, Maxima, MRV, AOPTix, and many others). While not all these companies failed, their FSO products failed to achieve anything close to their original deployment expectations. For example, LightPointe is now selling a wide range of millimeter wave RF transmission solutions. So, what is the problem?
The fundamental problem is that the terrestrial environment is not friendly to FSO. First, the weather has a habit of bringing links down even with robust optical fade margins – especially fog, snow, and rain. Second, receivers may obtain interference directly from the sun or reflections within the receive acceptance angle and transmitter paths may be scattered by heat rising from rooftops and other surfaces (via scintillation). Third, simple vibrations can throw transmission beams off alignment from receivers and their effect is amplified at longer distances.
And then there are things like bats. In the 90s, I remember one rooftop-to-rooftop installation in Cote d’Ivoire that failed every evening. Remote troubleshooting could not resolve the problem: there was no discernible interference from an evening sun or reflection noticed at a certain time of day. One evening, a technician was on the rooftop and noticed that bats flocked out of the ventilators swarming in front of the transmission path for their evening feeding. Problem solved (or at least, root cause identified). Add to that interference from birds, wasp nests, spiderwebs, and so on – you get the picture.
For these reasons, FSO has been used as a last resort in terrestrial installations, or for purely temporary installations failing to achieve the uptime required. In spite of continued laser and receiver advancements to enhance range or data rate (e.g., wavelength diversity), new methods to correct for vibrations and scintillation (e.g., pneumatic tilt correction or rapidly deformable mirrors), dual path redundancy with parallel RF links, and many other innovations, the promise of FSO has been elusive, while also adding to system complexity and cost.
However, non-terrestrial installations may demonstrate a future for FSO. Navy ships and aircraft have used such technology for secure temporary low-speed or burst communications. The outer space environment—lacking snow, fog, and rain— is more suitable to the technology. Indeed, FSO is perhaps necessary for achieving meaningful data rates at interplanetary distances.
Lest this post sound overly negative, I must comment that failure is part of the innovation process and investors will likely continue investing in “next-gen” FSO startups. Perhaps they will get it right this time. Make your bets!