b) Middle cylinder with a lower refractive index, called the cladding. c) An outer protective polymer layer (usually polyurethane or PVC) called the jacket. For glass optical fibers, the diameter of the core ranges between 10-600 microns, the cladding thickness is between 125-630 microns, and that of the jacket varies between 250-1040 microns. For POF all diameters range between 750-2000 microns. As can be seen, one of the main differences between glass and plastic optical fibers is their diameter. This makes POF easier to handle. The material used for currently commercialized fibers (core and cladding) include pure glass (SiO2), plastic, or a combination of both. The use of one or the other material will be determined by such factors as quality and economics. Plastic optical fibers (POF) have the advantage of being made of cheaper materials than glass and to operate in the visible range of the spectrum. However, they show a high loss, and for that reason their applications are confined to short distance transmission. In spite of this, POF is widely used for medical and industrial instruments, and currently research is carried out about using POF as a replacement of copper wiring for data transmission in automobiles. If you use silica glass for the core, it must be high purity in order to allow the light to be transmitted along the core with minimal loss. Some of the advantages associated with the use of fiber optic cables are: 1) Immunity to Electromagnetic Interference Although fiber optics can solve data communications problems, they are not needed everywhere. Most computer data goes over ordinary wires. Most data is sent over short distances at low speed. In ordinary environments, it is not practical to use fiber optics to transmit data between personal computers and printers as it's too costly. Electromagnetic Interference is a common type of noise that originates with one of the basic properties of electromagnetism.