Introduction about optical fiber.
In a communication system generally, microwaves and radio waves are used. But the frequencies of these waves are low, so they have less energy. Due to the less energy, they cannot propagate to longer distances. So, if these waves are replaced with high-frequency waves such as light waves or optical waves then they can carry bulk information to longer distances without any interruption. In addition, the optical or light waves have high bandwidth so they can accommodate more channels at a time. Therefore, the optical waves are used as carrier waves then they can show more advantages to traditional/coaxial cable/conventional communication systems. If the optical waves are directly sent into the atmosphere by combining with signal waves then, there we can observe a lot of disturbances like refraction, dispersion, polarization etc., in the atmosphere. Hence, to use the optical waves are carrier waves a guiding medium is required. Here, the guiding medium is called optical fiber
Optical fibre is a long cylindrical hair-thin structure, which guides the information-carrying light waves. It consists of three parts. The innermost part is called a core (denser), the next part is called a cladding (rarer) and the outer part is called a shield. Here, the selection of core and cladding depends on their refractive indices. The refractive index of the core is greater than the refractive index of the cladding.
The transmission of a signal through an optical fiber depends upon the principle called total internal reflection.