Cables and Connecters.

Cabling of fibers is necessary to protect them from deterioration during transportation and installation. Cable design depends on the type of application. For some applications it may be enough to buffer the fiber by placing it inside a plastic jacket. For others the cables must be made mechanically strong by using strengthening elements such as steel rods.

A light-duty is made by surrounding the fiber by a buffer jacket of hard plastic. A tight jacket can be provided by applying a buffer plastic coating of 0.5.1mm thickness on top of the primary coating applied during the drawing process. In an alternative approach the fiber lies loosely inside a plastic tube. Microbending losses are nearly eliminated in this loose-tube construction, since the fiber can adjust itself within the tube. This construction can also be used to make multifiber cables by using a slotted tube with a different slot for each fiber.

Heavy-duty cables use steel or a strong polymer such as Kevlar to provide the mechanical strength. In the loose - tube construction, fiberglass rods embedded in polyurethane and a Kevlar jacket provide the necessary mechanical strength . The same design can be extended to multifiber cables by placing several loose-tube fibers around a central steel core. When a large number of fibers need to be placed inside a single cable , a ribbon cable is used .

The ribbon is manufactured by packaging typically 12 fibers between two polyester tapes. Several ribbon are then stacked into a rectangular array which is placed inside a polyethylene tube. The mechanical strength is provided by using steel rods in the two outermost polyethylene jackets.The outer diameter of such fiber cables is about 1.1.5cm.

Connectors are needed to use optical fibers in an actual communication system. They can be divided in to two categories. A permanent joint between two fibers is known as a fiber splice, and a detachable connection between them is realized by using a fiber connector. Connectors are used to link fiber cable with the transmitter ,while splices are used to join fiber segments.

 The main issue in the use of splices and connectors is related to the loss. Some power is always lost, as the two fiber ends are never perfectly aligned in practice. Splice losses below 0.1db are routinely realized by using the technique of fusion splicing. Connector losses are generally larger. State-of-the-art connectors provide an average loss of about 0.3db.