All-silica fiber is an 
optical fiber composed of 
silica-glass  core and cladding.  
Refractive index of the core glass is higher than refractive index of the glass forming the cladding. The cladding of an all-silica fiber shouldn’t  be confused with the polymer overcoat of the fiber.
Synonyms: all-glass fiber, silica-silica fiber.
 
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