Fiber optics is the set of technologies that enables the point-to-point transmission of signals in the form of light—instead of in the form of electricity. The main component is optical fiber, the thread of glass-like material that carries the optical signal. Two related components are: (1) the light emitting diode (LED) and its advanced cousin, the semiconductor diode laser, which convert electrical signals to optical signals and couple them into the fiber; and (2) the photodiode, which receives optical signals from the fiber and converts them back to electrical signals.

Although fiber optics has many applications, including its use in sensors, its greatest impact has been in telecommunications. For millennia, humans used optical technology to send signals over distance—for example, as smoke puffs, reflected sunlight, or flares. Remember American Revolutionary War hero Paul Revere's ride and the warning signal: "one if by land and...