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Fiber fabrication
This document discusses the materials and fabrication of optical fibers. It covers the requirements for fiber materials, including being able to form thin flexible fibers, transparency at optical wavelengths, and having materials with slightly different refractive indices for the core and cladding. The main types of fibers are described as glass, plastic, and photonic crystal fibers. The two primary methods for manufacturing fibers are the liquid phase or melting method, and chemical vapor deposition methods. Specific techniques like the preform method, double crucible method, and modified/plasma chemical vapor deposition are outlined. The roles of dopants like germanium dioxide and phosphorus pentoxide in increasing the refractive index are also summarized.
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Fiber fabrication
- 1. Fiber Materials &Fabrication Available at kalyan5.blogspot.in OFC Unit 4 Kalyan Acharjya E-mail: kalyan.acharjya@gmail.com kalyan5.blogspot.in
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- 3. Already Covered: FiberMaterials Requirements (SiO2). Important Desirable Characteristics of Fiber Materials. Which Materials used for Doping Oxide or Fluride What is ZBLAN or ZHBLAN? Active Fibers (Doped with rare earth elements, such as Erbium & Neodymium) kalyan5.blogspot.in
- 4. Fiber Materials Requirements It must be possible to make long thin, flexible fibers from the material Material must be transparent at a particular optical wave length in order for fiber to guide light efficiently Physically compatible materials that have slightly different refractive indices for core and cladding must be available kalyan5.blogspot.in
- 5. Types of Fiber Glass Fiber Plastic Fiber Photonic Crystal Fiber kalyan5.blogspot.in
- 6. Methods to Manufacture: Liquid Phased (or Melting ) Method ChemicalVapour-phased oxidation Method Optical Glass Fiber kalyan5.blogspot.in
- 7. Liquid Phased (orMelting ) Method Draw the fiber from molten glasses, which are placed in two concentric crucibles (Double Crucible method) or Draw from a glass rod called preform. Fabrication of the Preform Drawing the fiber from the Preform Coating, Jacketing and labeling Process Now a Days most fab foundry used Preform Method kalyan5.blogspot.in
- 8. Liquid Phased (orMelting ) Method kalyan5.blogspot.in
- 9. Liquid Phased (orMelting ) Method Prefrom is fed into circular heater called drawing furnace. Preform end is softened to the point where it can be drawn into a very thin filament which becomes optical fiber The speed of the drum at the bottom of draw tower determines how fast and in turn how thick the fiber is An elastic coating is applied to protect the fiber kalyan5.blogspot.in
- 10. Liquid Phased (orMelting ) Method kalyan5.blogspot.in
- 11. Double Crucible Method Silica and halide glass fiber can all be made using a direct- melt double crucible technique Glass rods for the core and cladding materials are first made separately by melting mixtures of purified powders These rods are then used as feedstock for each of two concentric crucibles Advantage of this method is being a continuous process Careful attention must be paid to avoid contaminants during melting kalyan5.blogspot.in
- 12. Vapour-phased oxidation Method 1.Modified ChemicalVapor Deposition (MCVD) 2. Plasma Modified ChemicalVapor Deposition (PMCVD) 3. Plasma ChemicalVapor Deposition (PCVD) 4. OutsideVapor Deposition (OVD) 5. Vapor-phase Axial Deposition (AVD) kalyan5.blogspot.in
- 13. Chemical Vapor Deposition(CVD) All these methods are based on thermal chemical vapor reaction that forms oxides They are deposited as layers of glass particles called soot Starting materials are solutions of SiCl4, GeCl4, POCl3, and gaseous BCl3. These liquids are evaporated within oxygen stream and form silica and other oxides. Chemical reactions proceed as follows: SiCl4 + O2 -> SiO2 + 2 Cl2 GeCl4 + O2 -> GeO2 + 2 Cl2 4 POCl3 + 3 O2 -> 2 P2O5 + 6 Cl2 4 BCl3 + 3 O2 -> 2 B2O3 + 6 Cl2 kalyan5.blogspot.in
- 14. Remember! Germanium dioxideand phosphorus pentoxide increase the refractive index of glass Boron oxide decreases the refractive index of glass. These oxides are known as dopants. Changing composition of the mixture during the process influences refractive index profile of the preform kalyan5.blogspot.in
- 15. Chemical Vapor Deposition(CVD) ChemicalVapor Deposition is chemical reactions which transform gaseous molecules, called precursor, into a solid material , in the form of thin film or powder, on the surface of a substrate . kalyan5.blogspot.in
- 16. Modified Chemical VaporDeposition (MCVD) kalyan5.blogspot.in
- 17. For Detail PleaseRead: Chapter 6 kalyan5.blogspot.in
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