TL;DR: Fiber optic cables transmit data by exploiting total internal reflection, the refractive index difference between core and cladding materials, low optical attenuation in ultrapure glass, and the capacity for wavelength division multiplexing. Reflectance (which has also been called "back reflection" or optical return loss) of a connection is the amount of light that is reflected back up the fiber toward the source by light reflections off the interface of the polished end surface of the mated connectors and air. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube. The tool that everyone should have to take optical return loss measurements is an Optical Time Domain Reflectometer (OTDR). An OTDR allows you to measure your entire link, and will even give you a map that will tell you at what distance the pair of connectors are that need to be cleaned or just. Optical fibers are circular dielectric wave-guides used to contain and transmit light over short or long distances. Together, these properties allow light signals to.
