Different types of cable are used for different applications. The optic fibers are typically individually coated with plastic layers and encased in a protective tube suitable for the environment the cable will be used in. For example, indoor applications, the fiber is usually enclosed with a flexible fibrous polymer strength members like Kevlar. The end of the cable may be terminated with a specialized optical fiber connector to allow easy connection and disconnection to equipment that receives and transmits information. For a more strenuous environment, optic cable that is more robust and that will hold up to the elements is required.

A critical concern for outdoor cabling is to protect the fiber from being contaminated by water. In this application, copper tube instead of lightweight plastic is used along with a water repellant jelly or water absorbing powder. In outdoor settings where the optic cables can be exposed to animals or construction work, an armored process can be utilized.

However, how does fiber-optics work? The simplest explanation…is to compare it to “Morse Code” messages transmitted between ships. On a ship the sailors have floodlights which are situated behind venetian blind type shutters. One sailor has decoded the message and uses the floodlight to transmit the message and on the opposite ship another sailor receives the message, and decodes it and provides the message to the Captain! The fiber-optic relay systems works in much the same way.

It has a transmitter; which produces and encodes the light signals, optical fiber; which conducts the light signals over a distance, an optical regenerator; which boosts the light signal (for long distances), and an optical receiver; that receives and decodes the light signals.