An optical fiber is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter typically slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications. Fibers are used instead of metal wires because signals travel along them with lesser amounts of loss; in addition, fibers are also immune to electromagnetic interference. Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction.
Here is a collection of videos that introduce you how the fiber optics technology works:
How Fiber Optics Work
How It’s Made, Fiber Optics.
Understanding Fiber Optic Connector Types
Splice-On Connector Termination: 3mm Cable
Fiber Optic Training Featuring Splicing in PCH-01U
Power Meter Light Source Testing