Links between cities and cables that run alongside roads and into houses and officers are certainly impressive — and without them we wouldn’t have high speed internet. The secret world of submarine cables article tells that Internet’s largest and most important champions are the privately-owned submarine cables that orbit the Earth. The submarine telecommunications industry has deployed the core of the global fiber grid by setting up full duplex telecommunications solutions between continents. Across these cables, which span distances of up to 13,000 km, terabits of information squirt from one side of the planet to another. These fiber optic cables are just three inches thick, and have total capacities of between 40Gbps and 10Tbps. These solutions rely on fiber-optic cables, equipped with high reliability submerged repeaters, which are DC-powered through subsea cable from power feeding equipment in the shore stations.
The generation of submarine fiber-optic cables that revolutionized trans-oceanic telecommunications a decade ago is being retired prematurely. New Life For Undersea Fiber article tells that once the marvel of the telecom world, the first undersea fiber optic cables have reached the point of telecom obsolescence some years ago. The downfall of the first generation of submarine fiber-optic cables was their need for repeaters-devices that boosted the signal strength periodically to enable the information-carrying light waves to span the whole ocean. Early fiber repeaters had to convert faint optical signals to electronic form so they could be amplified, then convert the electrical signals back into light.
In the late 1980s, a new kind of optical fiber was developed that could amplify weak optical signals. An optical fiber amplifier can simultaneously amplify dozens of optical channels since they do not convert each channel into electronic signals separately. Optical fiber amplifier is a section of optical fiber that is doped with a rare-earth element such as erbium or praseodymium and powered with pump laser. Optical fiber amplifier was a huge improvement because it can amplify many signals at different wavelengths at the same time. DWDM is a real boon for oceanic optical fiber cables, allowing the increase of bandwidth without laying new cables undersea. In fact, the utilization of DWDM technology for submarine cable design is trending toward less fiber pairs per cable, significantly reducing the costs associated with intercontinental connections. Many of these use 80 DWDM channels at up to 10 Gbps per fiber pair.
A common sea-going fiber type specification is G.654. Rarely used terrestrially, G.654 fiber is a modified version of the G.652 fiber specification. With G.654, attenuation loss of optical fiber (less than 0.2 dB per km) is reduced to the minimum. Fiber amplifiers still require electrical power, which is fed to them through insulated copper cables, essentially superoceanic electrical extension cables that run down the length of the fiber cable.
Unrepeatered Submarine Fiber Optics Systems represent a new market opportunity for existing and new players in the market. As the technology has developed the capability of unrepeatered undersea fiber optic links continues to increase, opening up new markets where only the cable is placed underwater and the electronics are located in a benign environment on the shore. Unrepeatered systems also require less investment and lower cost for installation and operation. Hence, many smaller players are now able to enter the market. Similar to the repeatered long distance systems, unrepeatered systems are being driven by the unprecedented growth of the internet.
Both old and new ways of sinking a cable into the Pacific, Atlantic, Indian, and even Arctic Oceans requires a billion-dollar logistical feat that requires months or even years to enact. The secret world of submarine cables article has nice map of cables. Read more about optical submarine cables on Wikipedia. Undersea cable system: Technical overview & cost considerations is also good reading.