Optical fibers can be made of plastic or silica glass. An optical fiber made of silica glass is called Silica fiber or all-glass fiber. The core and cladding of an all-silica fiber is surely silica, but the protective coating does not need to be silica. The protective coating may be with any polymer.
Optical fibers used for telecommunication is mainly All-silica fibers. Singlemode fibers complying with ITU-T recommendations G.652, G.653, G.654, G.655, G.656 and G.657 are all-silica fibers. Multimode fibers having core diameters of 50 and 62.5 micrometers are also all-silica fibers.