The light entering the cladding is lost, causing attenuation. However, optical fibers are not perfect, and there will be. A high loss on a fusion splice can mean that the fusion of the two fibers may not have properly occurred and you have a weak slice that could fail pre-maturely. Fiber engineers will design a build and account for losses. Typical cable. Attenuation describes the continuous loss along the fiber, while insertion loss describes the additional loss caused by components such as connectors, splices, or splitters. It's measured in decibels per kilometer (dB/km), and it determines how far a signal can travel before it becomes too weak to read. Losses can be introduced by various means such as intrinsic material absorption, scattering, bending, connector loss and more.
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