Brief Introductory about Fiber Fabrication

1. Fiber Materials & Fabrication
Available at kalyan5.blogspot.in
OFC Unit 4
Kalyan Acharjya
E-mail: kalyan.acharjya@gmail.com
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2. Reference-Chapter 6
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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)
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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
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5. Types of Fiber
 Glass Fiber
 Plastic Fiber
 Photonic Crystal Fiber
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6. Methods to Manufacture:
 Liquid Phased (or Melting ) Method
 ChemicalVapour-phased oxidation Method
Optical Glass Fiber
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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
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8. Liquid Phased (or Melting ) Method
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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
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10. Liquid Phased (or Melting ) Method
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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
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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)
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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
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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
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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 .
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16. Modified Chemical Vapor Deposition (MCVD)
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17. For Detail Please Read: Chapter 6
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Fiber Cable:

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