• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Electrical Engineering News and Products

Electronics Engineering Resources, Articles, Forums, Tear Down Videos and Technical Electronics How-To's

  • Products / Components
    • Analog ICs
    • Battery Power
    • Connectors
    • Microcontrollers
    • Power Electronics
    • Sensors
    • Test and Measurement
    • Wire / Cable
  • Applications
    • 5G
    • Automotive/Transportation
    • EV Engineering
    • Industrial
    • IoT
    • Medical
    • Telecommunications
    • Wearables
    • Wireless
  • Learn
    • eBooks / Handbooks
    • EE Training Days
    • Tutorials
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • White Papers
    • Design Guide Library
    • Digital Issues
    • Engineering Diversity & Inclusion
    • LEAP Awards
    • Podcasts
    • DesignFast
  • Videos
    • EE Videos and Interviews
    • Teardown Videos
  • EE Forums
    • EDABoard.com
    • Electro-Tech-Online.com
  • Bill’s Blogs
  • Advertise
  • Subscribe

Free-space optical links, Part 3: Standard units

August 10, 2021 By Bill Schweber

Free-space optical links provide a reliable, cost-effective, and quick way to link two fixed communication nodes located a few kilometers apart.

The previous part of this article looked at real-world issues that make a practical FSO link a design challenge. This part looks at a family of commercially available FSO systems.

Q: Can you build your own FSO link?

A: Yes and no. All the parts are standard off-the-shelf components such as the P-70A ultrafast, InGaAs PIN photodetector from MACOM (Figure 1.) This proprietary, back-illuminated semiconductor diode design optimizes speed, sensitivity, and low polarization dependence for both 1310 nm and 1550 nm wavelengths. The detector is mounted in a compact 8-pin butterfly-style package.

Fig 1: This InGaAs PIN photodetector is well-suited for FSO link receivers, as it handles multiple wavelengths. (Image: Macom)

Q: So why do you also say “no?”

A: An FSO link is a complicated integration of electronics, electro-optical components, lenses, mechanical design, and more. Given the speed at which it operates, and its electronic and optical nature, everything has to be electrically, mechanically, and optically precise, stable, and consistent. Further, testing such a system is a significant task.

Q: What’s the alternative?

A: FSO link systems are available from over a dozen manufacturers, with some broad-application models and others more tightly focused on application niches. We’ll look at the Canon Canobeam family due to its popularity, longer history, spread of models and features.

Q: What’s an overview of this Canobeam family?

A: The first unit, the Canobeam 1, was introduced in 1993 and then expanded to become the broader Canobeam DT-100 family with faster systems, smaller ones, and ones with additional user-side interfaces and system features (Figure 2). A DT-100 for one node (you’ll need two) costs between $20,000 and $50,000.

Fig 2: The Canobeam DT-100 family comprises a series of general similar FSO units in identical enclosures, each with slightly different performance capabilities. (Image: Canon)

Q: What are the basic performance specifications for these units?

A: The DT-110 and DT-120 support 25 Mbps to 156 Mbps links at distances up to 0.5 km and 1 km (typical)  respectively and twice that under favorable conditions. The DT-130 is for links up to 1.25 Gbps and 1 km nominal.

Q: What about size and power?

A: All units in the family are in the same-size enclosure measuring about 50 cm front-to-back, 25 cm wide, and 17 cm high. The units weigh about 8 kg and require just 20 W from a standard AC line (48 V power is also an option).

Q: Is there a special feature in these units?

A: Yes, all units in the Canobeam family come with an autotracking function – a form of adaptive optics – that adjusts the laser-beam axis to compensate for slight movements in the building or installation base due to temperature variations or vibration due to wind and other factors (Figure 3). An internal processor calculates the point of maximum light input and controls the laser axis as needed.

Fig 3: All members of the Canobeam family include an autotracking function with adaptive optics to maintain beam alignment despite vibration and shifts dynamically. (Image: Canon)

Q: Are there any other features of interest?

A: Yes, units in this family (and most units from other vendors) can be “daisy-chained” in repeater mode for longer distances. In other words, site A links to site B via FSO, where two units are installed and connected. The second unit at site B then links via FSO to a unit at site C.

Q: What is an example of a quick set-up-and-go application in contrast to fixed installation?

A: FSO systems can be used to cover live news or sports events, where the mobile video camera link to one FSO whose beam crosses over city streets, parking lots, and traffic to another FSO, which in turn connects to the mobile studio van (Figure 4).

Fig 4: An FSO can be the fastest, easiest way to provide a quick set-up or temporary link for news, sporting event, or concert situations. (Image: Canon)

Conclusion

Terrestrial free-space optical links are alternatives to optical fiber or RF links for high-speed data interconnection over moderate distances. This approach offers convenience, reliability, ease of setup and use, and other advantages. The hardware and installation costs make them a viable option in many limited-range situations. They have issues with path interference due to various external factors, and these have been carefully studied and analyzed to optimize system performance.

Related EE World Content

Is Li-Fi “To Be” or “Not To Be”? Part 3 – Status
Calgary signs on for Terabeam FSO gear
LightPointe receives FSO patent

References

  • Wikipedia, “Free-space optical communication”
  • Science Direct, “Free-Space Optical Communication”
  • IEEE, “A Survey of Free Space Optics (FSO) Communication Systems, Links, and Networks”
  • Stanford University, “Free-Space Optical Communications — References”
  • Purdue University, “Designing A Free-Space Optical/Wireless Link”
  • Macom, “Free-space Optical Communication”
  • Intech Open, “Free Space Optical Communications — Theory and Practices”
  • European Scientific Journal, “Free Space Optical Communications: An Overview”
  • RTU/Kota, “Seminar Report on Free Space optic”
  • Arvix, “Free Space Optical Communication: Challenges and Mitigation Techniques”
  • Military & Aerospace Electronics, “Navy looks for companies able to build optical communications between aircraft and submarines”
  • Proceedings of SPIE “Research in Free Space Optical Data Transfer at the U. S. Naval Research Laboratory”
  • StartUs Insights, “4 Top Free Space Optics Startups Impacting The Telecom Industry”
  • Light Reading, “Is It Finally Time for Free-Space Optics to Shine?”
  • Canon, “Canobeam DT-150”
  • Canon, “Canobeam”
  • CommConnect, “Free Space Optics”
  • Airlinx, “Canobeam’s Auto Tracking Feature”
  • fSONA, “SONAbeam FSO Systems”
  • FSona, “FSO Guide”

 

You Might Also Like

Filed Under: Analog IC Tips, FAQ, Featured Tagged With: FAQ

Primary Sidebar

EE Engineering Training Days

engineering

Featured Contributions

GaN reliability milestones break through the silicon ceiling

From extreme to mainstream: how industrial connectors are evolving to meet today’s harsh demands

The case for vehicle 48 V power systems

Fire prevention through the Internet

Beyond the drivetrain: sensor innovation in automotive

More Featured Contributions

EE Tech Toolbox

“ee
Tech Toolbox: Internet of Things
Explore practical strategies for minimizing attack surfaces, managing memory efficiently, and securing firmware. Download now to ensure your IoT implementations remain secure, efficient, and future-ready.

EE Learning Center

EE Learning Center
“ee
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.
“bills

R&D World Podcasts

R&D 100 Episode 10
See More >

Sponsored Content

Advanced Embedded Systems Debug with Jitter and Real-Time Eye Analysis

Connectors Enabling the Evolution of AR/VR/MR Devices

Award-Winning Thermal Management for 5G Designs

Making Rugged and Reliable Connections

Omron’s systematic approach to a better PCB connector

Looking for an Excellent Resource on RF & Microwave Power Measurements? Read This eBook

More Sponsored Content >>

RSS Current EDABoard.com discussions

  • AC amplifier, transistor with bias network
  • problem identifying pin purpose on PMA5-83-2WC+ amplifier
  • Voltage Regulator Sizing Question
  • Colpitts oscillator
  • How to best test Electrolytic capacitors for premature failure reduced life?

RSS Current Electro-Tech-Online.com Discussions

  • Wireless Headphone External Mic
  • Can I use this charger in every country?
  • LED circuit for 1/6 scale diorama
  • Electronic board faulty?!?
  • using a RTC in SF basic
Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

Footer

EE World Online

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • Electro-Tech-Online Forums
  • Engineer's Garage
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips

EE WORLD ONLINE

  • Subscribe to our newsletter
  • Teardown Videos
  • Advertise with us
  • Contact us
  • About Us

Copyright © 2025 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy