written 8.2 years ago by | • modified 8.2 years ago |
Mumbai University > Electronics and Telecommunication > Sem7 > Optical Communication and Networks
Marks: 5M
Year: May 2012
written 8.2 years ago by | • modified 8.2 years ago |
Mumbai University > Electronics and Telecommunication > Sem7 > Optical Communication and Networks
Marks: 5M
Year: May 2012
written 8.2 years ago by |
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 (light duty cables).
For others the cable must be made mechanically strong by using strengthening elements such as steel rods (heavy duty cables).
A light-duty cable 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 0.5–1 mm 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, fiber glass rods embedded in polyurethane and a Kevlar jacket provide the necessary mechanical strength (left drawing).
The same design can be extended to multifiber cables by placing several loose-tube fibers around a central steel core (middle drawing).
When a large number of fibers need to be placed inside a single cable, a ribbon cable is used (right drawing). The ribbon is manufactured by packaging typically 12 fibers between two polyester tapes. Several ribbons 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 1–1.5 cm.