Fiber, the full name of optical fiber, is a kind of pure glass fiber made of glass or plastic, and it is also a light transmission tool that uses the principle of total internal reflection to transmit light in these fibers. The first optical fiber in the world was made by Gao Kun, the father of optical fiber.
Optical fiber is mainly composed of fiber core and cladding, which are concentric glass cylinders. The refractive index n1 of fiber core is slightly higher than the refractive index n2 of cladding. When light waves are incident from the end face of optical fiber at a small angle, they will be totally or partially reflected at the interface between fiber core and cladding, and then reflected at the other interface. Such repeated reflection makes optical signals propagate forward. It is divided into SiO2 optical fiber, multi-component glass optical fiber, plastic-clad SiO2 core optical fiber and all-plastic optical fiber according to materials, and step optical fiber and graded optical fiber according to optical fiber structure. The principle is that the transmitting device at one end of the optical fiber uses a light emitting diode or a laser to send light pulses into the optical fiber, and the receiving device at the other end of the optical fiber uses a photosensitive component to detect the pulses.
Most optical fiber cores are glass fibers, and most wire cores of network cables are made of copper cores. In long-distance transmission, the transmission distance of single-mode optical fiber can reach 10-20kM, and that of multi-mode optical fiber can also transmit 2-3KM, which is much higher than that of network cables. Network cable is mainly used for the connection between devices, and optical fiber is mainly used for broadband communication.