From the August, 2014 Issue of Cabling Installation & Maintenance Magazine
By Sean Sheedy
Using a medium only slightly larger than a human hair, fiber-optic communication has transformed our world. Not only have fiber-optic communications eliminated the vast majority of previous network limitations, but this technology also has expanded the capabilities of networks far beyond previous expectations. Today’s world of mobile communications and video downloads is a direct result of the rapid and affordable deployment of powerful, reliable fiber-optic networks. If anyone ever develops a roster of “disruptive technologies,” (as Joseph L. Bower and Clayton M. Christensen did in their 1995 Harvard Business Review article titled “Disruptive Technologies: Catching the Wave,”), then fiber optics should be number one on that list.
Amazingly, the signal carried by the fiber is astoundingly fragile and becoming more so. After more than 20 years in the industry, I can confirm there really are only two threats to a fiber signal: too much bending and too much dirt. At a BICSI Conference in 2008, JDSU stated, “Contamination is the number-one reason for troubleshooting optical networks.” A major telecom company, rolling out a new fiber-to-the-home service, found that 16 percent of all their connectors on their expensive new network were sufficiently contaminated to cause performance problems. Cleaning is not merely important; it is critical to the long-term reliability of any network, and at the heart of the profitability of a successful fiber deployment. Field techs must be taught, and must be provided the right tools, to clean every endface, both sides, every time they are installed, tested or reconfigured.
Today’s networks have been greatly impacted by the deployment technologies such as wavelength-division multiplexing (WDM) and iterations of it including dense WDM (DWDM) and coarse WDM (CWDM). These technologies are all different variations on the same theme: inserting many wavelengths onto a single fiber, which allows telecommunication companies to expand the capacity of their networks without needing to install more cables under highways. By using these technologies, companies can accommodate multiple generations of technologies within their optical infrastructure without the expense and delays of having to constantly rebuild networks. The capacity of a network medium can be expanded, almost infinitely, simply by changing out the multiplexers and demultiplexers at each end. These capabilities were not a concern in the early days of fiber, when networks were slow and relatively rare; but today they are everywhere, and cleaning is critical.
Unhappily, multiplexers and demultiplexers are greatly affected by reflectance and dispersion within the fiber link, and one of the biggest variables causing backreflection and signal loss is dirt on the connectors. Moreover, any one of these environments can be greatly disrupted by heat dissipation from high-powered lasers or back reflection resulting from material mismatches and contamination. As our networks become powerful, they become more capable, so cleaning is now becoming even more important. If you are not cleaning your splices and connectors properly, your network is not running at its best-guaranteed.
About the Author
Sean Sheedy has worked for more than 20 years as a fiber-optic installer, troubleshooter, system designer, emergency-restoration technician inspector, project manager, sales manager, and consultant. He holds 30 industry-related certifications and is a certified instructor with The Fiber Optic Association and The Electronics Technicians Association. He has also developed and teaches fiber optic/copper communications installation and troubleshooting training courses. His experience includes work in all divisions of the military, various government agencies, federal and state prisons, as well as the commercial markets. He can be reached at email@example.com.