A protective coating of one or two layers of cushioning material, such as acrylate, encases the cladding and helps preserve the optical integrity of the fiber. This sheath reduces crosstalk between adjacent fibers and loss-increasing microbending that occurs when fibers are pressed against rough surfaces. An optical fiber cable buried in the ground typically contains 100 or more fibers bundled together.
By packing more colors (wavelengths) of light into its core, an optical fiber can carry more bits of data. The refractive index of the core is higher than that of the cladding. The total reflection of the light beam caused by the difference in the refractive index (density) of the fiber core and cladding keeps the light wave contained in the core.
Optical equipment converts voice or data electrons into bits of light called photons. The photons travel across long-distance fiber networks propelled by lasers and amplifiers.
Truncated cable enters a junction box where amplification takes place. Each individual fiber must be separated. The fibers are then attached to devices that amplify and transmit the signal.
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.