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.

An optical signal originates from a modulated light source, such as a laser, that feeds it into a strand of fiber. Launching conditions determine the effectiveness of fiber optic transmissions. Output power depends on the angle over which light is emitted, the size of the light-emitting area, the alignment of the light source and fiber, and the light collection characteristics of the fiber. 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.