Optical fiber is a technology used to transmit data by sending short light pulses along a long fiber, which is typically made of glass or plastic. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred. Although fiber optic cable is still more expensive than other types of cable, it's favored for today's high-speed data communications because it eliminates the problems of twisted-pair cable, such as near-end crosstalk (NEXT), electromagnetic interference (EIVII), and security breaches. Figure 1 shows the general cross-section of an optical. Optical fiber is a very thin strand of pure glass which acts as a waveguide for light over long distances.