The core diameter is extremely small, measured in microns and is clad in a special coating that has a very low index of refraction so that it reflects the light back into the fiber along the entire length of cable. Outside the core is the buffer, which is made of layers of. The core of a fiber optic cable is the thin glass or plastic center through which light signals travel. It's the functional heart of the cable, typically made of ultra-pure silica (silicon dioxide), and its diameter can be as narrow as 9 microns, roughly one-tenth the width of a human hair. Its emergence has greatly enhanced the speed and quality of data transmission. Optical fibers are mainly composed of three parts: the core, the cladding and the protective layer. The IoR indicates how much a light ray.
