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Optical fiber is mostly made from silicon dioxide(SiO 2 ) but some little amount of other materials are also used such as s as fluorozirconate, fluoroaluminate, and chalcogenide glasses as well as crystalline materials like sapphire, are used for longer-wavelength infrared or other specialized applications.Chemical compounds such as germanium tetrachloride (GeCl 4 ) and phosphorus oxychloride (POC1 3 ) can be used to produce core fibers and outer shells, or claddings, with function-specific optical properties.
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