Fiber optic cables are made primarily of ultra-pure glass, specifically silicon dioxide (silica), the same compound found in quartz and ordinary sand. The glass itself is just. Fiber optics made of glass, also called glass optical fibers, are a thin, flexible, and transparent material used for transmitting light or images across various applications. Each fiber is thinner than a human hair, yet it carries data as pulses of light across enormous distances. Single-mode fiber. They consist of three elements as shown in Figure 1: a central core, cladding and a protective coating.