WHY ARE OPTICAL FIBERS SO GOOD FOR COMMUNICATIONS?
The information-carrying capacity of an optical fiber is far greater than it is for its competitors: wires, coaxial cables, and microwave links. In addition, optical fibers are inexpensive to produce, do not conduct electricity (which makes them immune to disturbance by lightning storms, and other electromagnetic signals except nuclear radiation), do not corrode, and are of small size. The primary reason that optical fibers have very much larger information-carrying capacity than other media, is that they carry light: this might seem a trivially obvious observation but it has fundamental significance. The frequency of the light beams that travel along optical fibers is in the vicinity of two hundred trillion cycles per second (Hz). Compare this with the frequency of the latest generation of personal communication service (PCS) cellular wireless systems approximately two billion cycles per second (2 GHz). Consider the frequencies that must be transmitted for voice communications, which
