Optical fiber consists of a core and a cladding layer, selected for total internal reflection due to the difference in the refractive index between the two. This article explains the differences between LSZH, HDPE, and LDPE cable sheaths, and how to select the right option based on real deployment conditions. Its primary functions. A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable but containing one or more optical fibers that are used to carry light. What are they exactly and what need to pay attention when choosing a fiber cable. Your Source for Fiber Optics, Fiber Optic Drawing, Fiber Optic Lighting, Clean Room Packaging and Illumination Products since 1977.