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The core and the cladding of an optical fiber are made of highly purified silica glass (fused-Silica Fibers). An optical fiber is manufactured from silicon dioxide. There are two methods of Manafacturing. The first, The Double Crucible Method and another The Vapor Deposition Process. In the double Crucible method two crucibles, one inside the other made of platinum contain molten silica - that is being constantly fed to it as silica bars (feed tubes). The molten silica is also mixed with the required dopants, at the base fiber is pulled out.
Source: http://www.photonics.com/EDU/Term.aspx?TermID=3656
Crucible method powdered silica is melted, produces fatter, multimode fibers suitable for short-distance transmission of many light wave signals.In The Vapor Deposition Process we create a solid cylinder of core and cladding material that is then heated and drawn into a thinner, single-mode fiber for long-distance communication.There are more three types of Vapor Deposition Techniques: Outer Vapor Phase Deposition, Vapor Phase Axial Deposition, and Modified Chemical Vapor Deposition (MCVD). MCVD process is the most common manufacturing technique used in current days. MCVD yields a low-loss fiber well-suited for long-distance cables.
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