The Structure Of Optical Fibre
A good primer on the physical structure of an optical fibre strand with some basic physics to give you insight into how it really works. Optical fibre is an ultra pure, high quality glass designed to carry infrared laser signals encoding bits, in other words, zeros and ones. It consists of a core which is the optical highway for the laser light, a cladding designed to protect the core and prevent external light from reaching the core or light traversing the core from escaping, and finally, soft and hard plastic coatings as further protection. For full details, see https://learn.aflglobal.com/enterprise/the-basic-structure-of-optical-fiber.