Advantage and disadvantage of underwater fiber optics cable

An optical fiber or fiber optic cable is a flexible, transparent fiber made by drawing glass, which are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables.

Massive network of fiber optic cables lies deep under the seas across the Earth. The cables allow us to quickly send our emails and videos and connect our browsers and phone calls to sites in far-away lands. This network isn’t new. Submarine data cables date back to 1850 when the first international telegraph cable (with a capacity of 10 words per minute) spanned the channel between England and France. As early as 1901, telegraph cables crisscrossed the oceans and connected all the continents except for Antarctica. Subsequent cable generations included upgrades to telephone cables and data communications cables. Analog coaxial cables of steel-wrapped copper were widespread under the oceans beginning in the 1950s.

The underwater cable network is a critical component to global commerce, and it’s growing.

Today virtually all of the undersea long-haul communication cables are optical, as are land-based ones. Submarine data cables handle more than 95 percent of IP voice and data traffic between countries and continents, and 100 percent of international Internet traffic.

The fiber optic core is typically encased in high-tensile-strength galvanized steel wires surrounding a copper sheath, surrounded by more layers of steel armor and polyethylene insulation.

Submerged cables are laid down by using specially modified ships and sometimes they are even built for this purpose as they have to endure harsh conditions as well as huge pressures, these ships carry the submarine cable onboard and slowly lay it out on the sea bed as per the plans were given by the cable operator. The ships can carry with them up to 2,000 km of cable in length.

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Advantages

• Optical fiber offers low power loss, which allows for longer transmission distances. In comparison to copper, in a network, the longest recommended copper distance is 100m while with fiber, it is 2km.

• Fiber optic cables are immune to electromagnetic interference. It can also be run in electrically noisy environments without concern as electrical noise will not affect fiber.

• Optic cables have a much greater bandwidth than metal cables. The amount of information that can be transmitted per unit time of fiber over other transmission media is its most significant advantage.

• Fiber optic cable has nearly 4.5 times as much capacity as the wire cable has and a cross-sectional area that is 30 times less.

• An optical fiber has greater tensile strength than copper or steel fibers of the same diameter. It is flexible, bends easily and resists most corrosive elements that attack copper cable.

• Fiber optic cables are much thinner and lighter than metal wires.

• They occupy less space with cables of the same information capacity.

• The lighter weight makes fiber easier to install.

• Optical fibers are difficult to tap. As they do not radiate electromagnetic energy, emissions cannot be intercepted.

• As physically tapping the fiber takes great skill to do undetected, fiber is the most secure medium available for carrying sensitive data.

Disadvantages

• It would be difficult to repair it for 12 months a year.

• Very costly. The estimate to build the 24-Tbit/s capacity Arctic Fibre network is $620 million. Arctic Fibre is working to raise $220 million in equity funding from investors for a cable with 80 wavelengths at 100G.

• The most common threat to submarine cables is shipping and fishing activities. Roughly 70 percent of cable damage from anchor-dropping and trawling occurs in water less than 200 meters deep. Some interruptions appear to be intentional attacks, the motivations of which are difficult to discern. One of the worst service disruptions to date occurred 19 December 2008, when France Telecom announced that three major subsea optical cables were cut by either a ship’s anchor or bad weather. The damage disrupted 75 percent of the Internet service connecting Europe with the Middle East, North Africa and India until it was repaired on 31 December.

• Natural disasters such as mudslides and typhoons are also a threat to under-sea fiber.

• One of the biggest challenges facing the submarine optical network is that many parts of the world are still vulnerable to disruptions in service due to lack of redundancy.

• Cuts to cables in bottleneck areas, however, can slow down or even completely disrupt service for weeks.

• Unlike the cable itself, the biggest challenge to a repeater is its handling. The armor and interior of the repeater are jointed so that it can be bent for coiling onto the large cable spools that store the cable on the ship before deployment.

• The transmission on the optical fiber requires repeating at distance intervals. The fibers can be broken or have transmission losses when wrapped around curves of only a few centimeters radius.