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Fiber fabrication


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Brief Introductory about Fiber Fabrication

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Fiber fabrication

  1. 1. Fiber Materials & Fabrication Available at OFC Unit 4 Kalyan Acharjya E-mail:
  2. 2. Reference-Chapter 6
  3. 3. Already Covered:  Fiber Materials 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)
  4. 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
  5. 5. Types of Fiber  Glass Fiber  Plastic Fiber  Photonic Crystal Fiber
  6. 6. Methods to Manufacture:  Liquid Phased (or Melting ) Method  ChemicalVapour-phased oxidation Method Optical Glass Fiber
  7. 7. Liquid Phased (or Melting ) 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
  8. 8. Liquid Phased (or Melting ) Method
  9. 9. Liquid Phased (or Melting ) 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
  10. 10. Liquid Phased (or Melting ) Method
  11. 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
  12. 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)
  13. 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
  14. 14. Remember!  Germanium dioxide and 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
  15. 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 .
  16. 16. Modified Chemical Vapor Deposition (MCVD)
  17. 17. For Detail Please Read: Chapter 6
  18. 18. Fiber Cable:
  19. 19.