PRINCIPLE OF OPTICAL FIBER
An Optical Fiber is a thin flexible, transparent dielectric wave guide strand meant for communication light signal through it. It is based on the principle of total internal reflection (TIR). Light ones trapped within the fiber without being lost. An Optical Fiber consists of a core at the center with refractive index〖 n〗_1. This core is surrounded by cladding whose refractive index 〖 n〗_2 is slightly lower than 〖 n〗_1. outside the cladding a protective jacket called sheath is attached. The basic function of this sheath is to provide mechanical strength to the fiber and prevent it from abrasions due to surrounding.