Multimode fiber is best for short-distance applications, typically under 1 km. It is widely used in local area networks (LANs), data centers, and enterprise environments due to its lower-cost transceivers and easier light coupling compared to singlemode fiber. Polarization mode dispersion (PMD) results from slight imperfections in the fiber core, causing polarization-dependent delays that degrade signal quality. Multi-mode fiber has a fairly large core diameter that enables multiple light modes to be. Singlemode fiber has a small core. It lets light travel in many paths. Singlemode fiber features a small core diameter of just 9 µm and allows only one mode of light to propagate.
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