An optical fiber or optic fiber is a flexible, transparent fiber made of high quality extruded glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. For Solar Fiber we have done testing with optic fibers to see how we can incorporate those in textiles.
Optic fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. But by removing the cladding light can come out on all sides, as you can see here.