The Undersea Internet

The Internet is a vast network of undersea optical fiber cables that transmit data from around the world almost instantly. Upgrades in many of the components that make up this network are about to facilitate even more speed and versatility. These undersea fiber pairs can carry about a terabit (one trillion bits) per second of data, in the form of light pulses. The pulses travel thousands of miles underwater, getting refreshed every hundred miles or so by special amplifiers built into the cable system itself. Engineers are able to squeeze more information into a single cable by using a technique known as Wavelength Division Multiplexing (WDM). This method allows for multiplexing up to 100 signals, each at a different frequency or color, on top of each other.

Neal Bergano, a Managing Director at Tyco Telecommunications, a provider of undersea cable systems, said that the signal capacity of fiber optic cables is getting ready for a large growth spurt. The multiplexing is about to get better, and the devices that detect the signals emerging from the ocean are about to get more efficient. This will lead to an increase in transmission speed by a factor of 10 or more.

This is a significant improvement compared to the older transatlantic cables. The first official telegraphic message was sent in 1858, but the line went dead a few days later. A decade later, the lines were much better, but only bankers could afford to communicate with each other across the ocean. The price was more than $5 a word.

Undersea fiber service is about to get faster in countries that acquired high-speed telecommunications long ago, and it has also just come to some nations that have never used cables before. Bergano described an undersea network, called SEACOM, bringing terabits-per-second communications over a 15,000-kilometer network connecting several countries in East Africa, with side branches extending to Europe and India.

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