Coaxial cable and fiber are similar, but it has no mesh shield. The center is a light-transmitting glass core. In a multimode optical fiber, the diameter of the core is 15 mm to 50 mm, which is roughly equivalent to the thickness of human hair. And the single-mode optical fiber core has a diameter of 8 mm to 10 mm. The core is surrounded by a glass envelope having a lower refractive index than the core so as to hold the optical fibers within the core. Then there is a thin layer of plastic jacket, used to protect the envelope. The fiber is usually bundled and protected by a shell. Core is usually made of quartz glass cross-sectional area is very small double concentric cylinder, it is brittle, easy to break, so need to add a protective layer.

An optical fiber is a subtle and flexible medium that transmits a beam of light. Optical fiber cable consists of a bundle of fibers, referred to as optical cable.