How about 10 Gigabit fiber optic cables
Multiple vendors introduced single-strand, bi-directional 10 Gbit/s optics capable of a single-mode fiber connection functionally equivalent to 10GBASE-LR or -ER, but using a single strand of fiber optic cable. To implement different 10GbE physical layer standards, many interfaces consist of a standard socket into which different physical (PHY) layer modules may be plugged. In SMF light follows a single path through the fiber while in MMF it takes multiple paths resulting in differential.
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