Wavelength multiplexing is a good and affordable method of transmitting multiple signals across the same fiber. Light is an electromagnetic wave just like the radiofrequencies, so you can use it exactly in the same manner: send different signals one after the other. A WDM multiplexer, sometimes referred to as a mux, is the key to optimizing, or maximizing, the use of the fiber. That's how different packets not mix with each other. 2- Packets take turns going through the same channel, not being transmitted at the same time. It is just so fast that we perceive it to do so. Combined with Optical Add / Drop Multiplexer (OADM), one can. One participant introduces the concept of 'Multiplexing', specifically Wavelength-Division Multiplexing, as a method that allows multiple signals to be sent simultaneously using different wavelengths of light. Typical fiber specs are more than 100 times farther and 1000+ times faster! Try this for some more reading.
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