Hi,
Three types of material make up fiber-optic cables:
Glass
Plastic
Plastic-clad silica (PCS)
These three cable types differ with respect to attenuation.
The attenuation of PCS fiber-optic cable falls between that of glass and plastic. PCS fiber-optic cable has a glass core, which is often vitreous silica, and the cladding is plastic, usually a silicone elastomer with a lower refractive index.