The use of optical fiber for communications purposes requires low=loss fiber cabling and connectors.Connectors and splices are utilized to connect fiber and to terminate the fiber at transmitter and receiver ends.Fabrication of the optical fiber is a complicated process involving ends.Fabrication of the optical fiber is a complex process involving the precise control of purity,refractive index, and diameter in order to obtain precise control of purity,refractive index, and diameter in order to obtain the lowest possible loss and meet application specifications.Cabling is necessary to protect the single and multiple fiber s from installation damage, tight bends, and harsh environments.While conventional electrical connector types are relatively simple, fiber connectors require great precision to ensure minimal losses at an interface.Splices serve as a quick and easy way of permanent connection between fibers.Splices generally have less loss than connectors, as the connection is permanent.In this chapter we will describe the various fabrication processes for both fiber and cable and demonstrate how an understanding of fiber,cable connectors, and splices is essential to understand fiber optic communications systems.
Fiber Cabling Considerations
Fiber cable provides the protection and ease of handling required for the wide variety of actual application conditions.The fibers must be sheathed so that they can withstand the extremes of enviroment,installation forces,and stresses and, at the same time, be easy to manufacture, and transport.With structures similar to those of conventional electronic cabling,fiber optic cables for communications require more added protection due to the fragile nature of glass fiber . Connector tolerances are much tighter as well, due to the alignment precision required.
Fiber Cable Construction
Most fiber cables include a buffer jacket, which surrounds the fiber, strength member.While a plastic buffer is added to the fiber initially,cable manufactures then add an additional loose buffer or tight buffer.The loose buffer consists of a plastic tube,which is over twice the fiber diameter in size and serves as a shield from stresses and temperature changes. As the fiber experiences bending,pressure, or extreme temperatures, the buffer protects the fiber and leaves room for movement and expansion.It is in this concept, was later born Plastic Optical Fiber Cable . The tight buffer consists of a plastics buffer deposited directly on the fiber coating.While differences in thermal expansion between fiber and buffer may cause micropenis, this configuration provides better mechanical protection and allows for tighter cable turns than the loose structure, loose structure.
Types of cables
Fiber optic cables may be classified by the type of installation environment or the number of individual fibers.They may be for indoor or outdoor use and can consist of one (Simplex Fiber Optic Cable ). Two (duplex fiber cable),or more (multiplier) individual fibers.A variety of simple indoor cables, simplex cables provide one-way transmission,while Duplex Fiber Optic Cable allow translation in both directions. Multiplier cables may carry many fiber pairs surrounding a central strength member as shown in the outdoor cables of figure 3-9; or they may take the form of ribbon cables which are individual tables in a row surrounded by a single jacket.