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Improvements in Undersea Fiber

We often forget that a lot of things we do on the web rely on broadband traffic that passes through undersea cables. Any web traffic from overseas gets to the US through one of the many underwater fiber routes. Like with all fiber technologies, the engineers and vendors have regularly been making improvements.

The technology involved in undersea cables is quite different than what is used for terrestrial fibers. A long fiber route includes repeater sites where the light signal is refreshed. Without repeaters, the average fiber light signal will die within about sixty miles. Our landline networks rely on powered repeater sites. For major cross-country fiber routes, multiple carriers often share the repeater sites.

But an undersea cable has to include the electric power and the repeater sites with the fiber since the cable may be laid as deep as 8,000 beneath the surface. HMN Tech recently announced a big improvement in undersea electronics technology. On a new underseas route between Hainan, China and Hong Kong, the company has been able to deploy 16 fibers with repeaters. This is a vast improvement over past technologies that have limited the number of fibers to eight or twelve. With 16 lit fibers, HMN will be able to pass data on this new route at 300 terabits per second.

Undersea fibers have a rough existence. There is a fiber cut somewhere in the world on underseas fiber every three days. There is a fleet of ships that travel the world fixing underseas fiber cuts or bends. Most underseas fiber problems come from the fiber rubbing against rocks on the seabed. But fibers are sometimes cut by ship anchors, and even occasionally by sharks that seem to like to chew on the fiber—sounds just like squirrels.

Undersea fibers aren’t large. Near to the shore, the fibers are about the width of a soda can, with most of the fiber made up of tough shielding to protect against dangers that come from the shallow waters near to shore. To the extent possible, an undersea fiber will be buried near shore. Further out to sea, the size of the fibers is much smaller, about the size of a pencil—there is no need to try to protect fibers that are deep on the ocean floor.

With the explosion in worldwide data usage, it’s vital that the cables can carry as much data as possible. The builders of the undersea routes only count on a given fiber lasting about ten years. The fiber will last longer, but the embedded electronics are usually too slow after a decade to justify continued use of the cable. Upgrading to faster technologies could mean a longer life for the undersea routes, which would be a huge economic benefit.

By Doug Dawson, President at CCG Consulting

Dawson has worked in the telecom industry since 1978 and has both a consulting and operational background. He and CCG specialize in helping clients launch new broadband markets, develop new products, and finance new ventures.

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