A special touch is required to splice fiber optic cable since the glass fibers are encased with fiber insulation sealed inside a plastic coating. Unlike copper, the fibers are delicate and can be easily broken by using too much pressure to cut the casing while splicing cables to connectors.
There are two principal types of splices: fusion and mechanical. Fusion splices use an electric arc to weld two fiber-optic cables together. The process of fusion splicing involves using localized heat to melt or fuse the ends of two optical fibers together. The splicing process begins by preparing each fiber end for fusion. Fusion splicing requires that all protective coatings be removed from the ends of each fiber. The fiber is then cleaved using the score-and-break method. Each fiber face to achieve a good optical finish by cleaving and polishing the fiber end. Before the connection is made, the end of each fiber must have a smooth finish that is free of defects such as hackles, lips, and fractures. These defects, as well as other impurities and dirt change the geometrical propagation patterns of light and cause scattering. The quality of each fiber end is inspected using a microscope. In fusion splicing, splice loss is a direct function of the angles and quality of the two fiber-end faces.
The basic fusion-splicing apparatus consists of two fixtures on which the fibers are mounted with two electrodes. An inspection microscope assists in the placement of the prepared fiber ends into a fusion-splicing apparatus. The fibers are placed into the apparatus, aligned, and then fused together. Initially, fusion splicing used nichrome wire as the heating element to melt or fuse fibers together.The heater is usually an electric arc that softens two butted fiber ends and allows the fibers to be fused together.
Due to the cost of an electric arc and the time required to let the heated ends cool, other methods to connect broken fibers, such as mechanical splices and couplers, are more commonly used.
In Mechanical Splicing, mechanical splices are simply alignment devices, designed to hold the two fiber ends in a precisely aligned position thus enabling light to pass from one fiber into the other. Mechanical splicing is done in an optical junction where the fibers are precisely aligned and held in place by a self-contained assembly, not a permanent bond. This method aligns the two fiber ends to a common centerline, aligning their cores so the light can pass from one fiber to another.This task is accomplished with a portable workstation that is used to prepare each fiber end. That preparation includes stripping a thin layer of plastic coating from the fiber core before its splicing.
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