Have you ever wondered how the data we transmit through the internet is able to travel thousands of miles around the globe? Well, for the majority of the distance, the data travels as light signals in fiber optic cable. Signal propagation through optical fiber is based on the phenomena known as total internal reflection (TIR). When light travels through a material and encounters a new material which has a different refractive index, that light changes direction, or bends, when it enters the new material.
Sourced through Scoop.it from: blogs.cisco.com