Optical fiber consists of a and a layer, selected for due to the difference in the between the two. In practical fibers, the cladding is usually coated with a layer of or. This coating protects the fiber from damage but does not contribute to its properties. Individual coated fibers (or fibers formed into ribbons or bundles) then ha. Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the and tuning procedures that may be incorporated into optical connector manufacturing, connectors are often assembled onto optical fiber in a supplier's manufacturing facility. However, the assembly and polishing operations involved can be performed in the field, for example, to long runs at a.