![]() ![]() The outermost armor layer protects the cable in the harsh environment at the bottom of the ocean.ĭata transfer rates vary among the approximately 550 active cables running along the ocean floor. The cable could be 50mm or more with the additional protective armor, depending on the application. The total thickness of a submarine cable without additional protective armor is only about that of a garden hose, approximately 20mm. Surrounding the fibers are various layers of protection and insulation. Submarine cables are typically composed primarily of marine-grade polyethylene with steel strength members, copper conductors, and a glass fiber core.Īt the core are the silicon glass optical fibers themselves, each of which is not much thicker than a human hair. Submarine cable structureĪ submarine cable is made up of several layers. ![]() The image below is of a typical submarine cable amplifier, though they can vary in size. If power is lost from one end, the other power source can power the amplifiers throughout the cable until the power issue is resolved. Each power source powers half of the inline amplifiers. Most submarine cables are powered with about 20k volts from both ends. These amplifiers are placed about every 70 km or so to enable the signal to travel vast distances while maintaining signal integrity. The amplifiers, sometimes called repeaters, are installed inline as part of the cable to restore the signal. However, attenuation is not zero, so the signal does need to be repeated or amplified at prescribed points in the path of very long cables. Attenuation is in the range of 0.15db/km-0.17db/km, which means there is very little loss over long distances. G.654 compliant fibers have a zero-dispersion wavelength at about 1300nm and are optimized for use in the 1500 nm-1600 nm range. Low attenuation, or low signal loss, is important since crossing oceans means light will be traveling considerable distances. ![]() G.654E fibers are in the same family of fibers but are typically used for more unique land-based applications requiring an even lower loss fiber. Submarine optical fibers are typically G.654A-D, meaning they are single mode and have better attenuation than most common land-based fiber optic cable types. In the image below, notice how DWDM technology will take multiple data streams operating at different wavelengths and combine them for transport on a single optical fiber. The cables make use of Dense Wavelength Division Multiplexing (DWDM) to move large amounts of data by allowing different data streams in the form of multiple wavelengths of light to be sent simultaneously over a single fiber infrastructure. However, submarine cables need to allow light to travel very long distances with minimal attenuation, so the G.654 subset of fiber is used for undersea applications. The submarine cables that move internet traffic around the world are made from silica glass fiber optic strands that most network engineers are likely familiar with. This post will explore some of these areas starting with the technology itself. And in a recent episode of Telemetry Now, Alan Mauldin, Research Director for TeleGeography, explained that the world of submarine cables is about politics, money, the environment, global commerce, and of course, moving data vast distances across a wire. TeleGeograpy’s interactive map explores the world’s system of undersea fiber optic cables crossing oceans and following the coast of entire continents.
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