Undersea fber-optic cables make the web worldwide

摘要

The internet brings you data from around the world almost instantly. This information might come from New York, London, Mumbai, Tokyo, Sydney, Beijing, Rio de Janeiro, or Seoul and arrives in your continent not from satellite but from cables that sit on the bottom of the ocean. The earth's continents are connected with a web of undersea fber-optic cables that join the world's major population centers. Anyone who surfs the international Web, makes international phone calls, or simply tweets friends on other continents uses undersea fber-optic cables. Undersea fber-optic cables make the web worldwide. Undersea cables have been providing global connectivity for nearly 150 years. The first successful transatlantic telegraph cable connected North America to Europe and went into service in 1866, 34 years after the invention of the telegraph. It took nearly 90 years from the time that the frst telegraph cable was installed until the time when the frst transatlantic telephone cable was installed. In 1956, the TAT system (Transatlantic Telephone Cable) went into service with 36 4kHz telephone circuits between Newfoundland and Scotland. The frst fber-optic cables were installed in the 1980's using digital regenerators and then in the 1990's using Erbium-doped fber amplifers. Modern cable systems installed up to last year are capable of transmitting about 1,000GB/s over each fber pair. Today we are seeing another major paradigm shift in technology which promises to increase the usable capacity on long-haul fber-optic cable by another factor of ten.