The fiber optic cable core is the physical glass medium that transports optical signals from an attached light source to a receiving device. What Are All the Parts of a Fiber Optic Cable? In most cases, a fiber optic cable will have five primary components: the core, which is responsible for transporting the light signals; the cladding, which surrounds the core with a lower refractive index and contains the light; the coating, which. A TOSLINK optical fiber cable with a clear jacket. These cables are used mainly for digital audio connections between devices. This article is written to take a peek inside fiber optic cables. You will also learn how different aspects of the product can affect budget and design.