Authors: Arun katuwal, Masinde Masinde, Jonathan Malangoni, Ahmed Mursalat
Structure, Materials, Manufacturing
This article is about the structure, materials and manufacturing of optical fibers.
Table of Contents
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Background
An Optical Fiber is a flexible, transparent fiber made of extruded glass(silica) or plastic which is slightly thicker than human hair. It is smililar to the light pipe that is used to transmit light between the two ends of the fiber.Optical Fiber is mainly used in Communication, power Transmission, sensors and a lot of other things.
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Optical Fiber currently known as the fastest means for transfering data. But What exactly is used to make Optical Fiber. What are the materials used. And how are these manaufactured?
Structure
Fiber optics has three components Fiber Core, The Cladding and The insulating Jacket. The Fiber core is the Fiber cable that carries light Signals. The cladding is a material that surrounds the core - it reflects light back into the core. Like the core, the cladding also consists of glass or plastic materials but with different densities. And the insulating jacket acts as a sheath that protects the other parts from damage or water getting through.
Materials
The fundamentals for making optical fiber need materials which are transparent and can be drown into the fiber with the distinct core cladding structure that is uniform along the length of the fiber and will survive in the desired working environment. To make thin, uniform fiber the approach is to heat up a material until it softens into a very thick or viscous liquid and then stretch the thick fluid into the thin ligaments.Durability of the material is vital.The most common materials for years are silica based glass and certain plastics.
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The purity of the glass used effects the degradation of the light signal being sent, regular window glasses usually the thicker it is the less clearly you will see through it. However a 1 km thick glass used in optic fibers will allow you to clearly see the other side. Therefore in optic fiber manufacturing glass purity is extremely important.Manafacture of Optical Fibers
Manufacturing
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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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.
References
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