How do fibers work?
The fibers used in communications consist of a hair thin strand of glass coated with a plastic coating for mechanical protection. The actual glass strand is actually made up of two components: a core of between 9 and 62.5um in diameter surrounded by a cladding of lower refractive index glass with an outside diameter of 125um. There are other types of fiber both in terms of materials used and dimensions but the ones mentioned are by far the most common. Light travels in the core region by “Total Internal Reflection” which means that light rays bounce off the core cladding interface and make their way from the input of the fiber to the other end. A fiber with a 62.5 um core and 1 125um clading diameter is referred to as a 62.5/125um fiber.
