Optical bare fiber is most commonly made of silica and it has three components. The core that is made by drawing a very fine strand of highly pure glass from a pre-form into a very small “string”. This core is most often no more than 50 microns in diameter, but can be as small as 9 microns. The core is then covered with another layer of glass that is not as pure and this is called the cladding. The cladding’s purpose is to keep the optical signal traveling within the core of the fiber. The cladding is then covered with an acrylate coating so that the glass fiber can be handled and spooled without breaking.
