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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 Crucible Method and another The Vapor Deposition Process. In 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.
The glass fiber optics are made from silica, which is quite good at a big range of of wavelengths, and when the light being transmistted is close to infrared spectrum silica seems to have quite low absorption and scattering losses - this is mainly thanks to the extreme purity of silicon that is available. Silica is quite suitable mechanically, due to it having good strength against pulling and bending, it also is good due to the fact that it doesn't absorb water.
Plastic optical fibers tend to have a much higher attenuation, and thus its use becomes limited.
Impurities are the main cause of attenuation in standard silica glasses. Synthetic fused silica is the base for the communacation fibers, it is very clear because impurities are reduced to a part per billion or less. All plastic fibers have attenauation much higher than silica fibers. They are used for image transmission or short distance communications.
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