Optical fiber
Fiber and coaxial cable are similar, but there is no mesh shield. The center is the glass core of light propagation. In multimode fiber, the core diameter is 15mm ~ 50mm, which is roughly the same as the thickness of human hair. The diameter of single-mode fiber core is 8 mm ~ 10 mm. The core is surrounded by a glass envelope with a lower refractive index than the core to keep the fiber in the core. On the outside is a thin plastic jacket to protect the envelope. The fiber is usually bundled and protected by a shell. The core is usually a double-layer concentric cylinder made of quartz glass with a small cross-sectional area. It is brittle and easy to break, so it needs an additional protective layer.
optical cable
Optical fiber is a fine and flexible medium for transmitting light beam. The optical fiber cable consists of a bundle of fibers, which is called optical cable for short.