Multiplexers are used to combine several wavelengths onto a single glass fiber so data can be transported more efficiently. Since photons are much lighter than electrons, they travel at exceptionally higher speeds and encounter less resistance in a strand of glass fiber. However, light traveling through a fiber optic cable loses its strength naturally over distance because of absorption and scattering losses. Due to this loss of strength, the signal needs to be amplified about every 200 kilometers with repeaters and other devices. Attenuation is the single most important factor determining the cost of fiber optic telecommunication systems.
Attenuation is the loss of optical energy a signal experiences as it travels through optical fiber.
It determines the spacing of repeaters needed to maintain acceptable signal levels. At the receiving end of the fiber, demultiplexers and receivers decode the optical signal and convert it back to electrons for use by computers and other equipment. New all-optical network technology promises to speed up the transmission process. For instance, with an all-optical switch, optical signals do not need to be converted into electrons before being routed to their destination. An outer glass cladding reflects light, trapping it inside the core.