Optical cable sheaths are essential components in modern telecommunications, providing protection and durability to delicate fiber optic strands. They shield fibers from environmental damage, mechanical stress, and chemical exposure, ensuring reliable data transmission over long distances. As. The core, cladding, and coating are at the forefront of its design, each contributing essential functions to facilitate effective data transfer through light signals. Overview. Quick Answer: A fiber optic cable is built in concentric layers. Inside out: glass core (8 to 62.