Optical fibre communication basics


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Course: Semiconductor Physics for B.Tech
Topic: Basics of Optical Fibre Communication

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Optical fibre communication basics

  1. 1. Semiconductor PhysicsOPTICAL FIBER COMMUNICATION http://amitbiswal.blogspot.com
  2. 2. Processes involved Generation Modulation Transmission Amplification Reception by photo detectors http://amitbiswal.blogspot.com
  3. 3. General communication SystemInformation Transmitter Transmission Receiver Source (Modulated) medium (Demodulator) Destination http://amitbiswal.blogspot.com
  4. 4. Types of optical fibers Step-index single mode fiber Step-index multi mode fiber Graded index multi mode fiber http://amitbiswal.blogspot.com
  5. 5. Absorption & Emission ofradiation Absorption Spontaneous emission Stimulated emission http://amitbiswal.blogspot.com
  6. 6. Diagrammatic representation E2hv= E2-E1 E1Absorption E2 hv= E2-E1 E1 Spontaneous Emission E2 hv= E2-E1 E1 Stimulated Emission http://amitbiswal.blogspot.com
  7. 7. Population Inversion Necessary condition for stimulated emission Process of accumulation of e- at E2 level and vacuum states at E1 level Required to:  Enhance radioactive recombination  To move fermi level into CB & VB.  To cause accumulation of e- in CB & VB  Responsible for laser action http://amitbiswal.blogspot.com
  8. 8. Layers surrounding Fibercables Primary coating  Gives additional mechanical strength  Protects fiber from stress  Protection against chemical attacks Buffer jacket  Avoids the formation of microbends  Bending stress is relieved  Fiber losses are reduced http://amitbiswal.blogspot.com
  9. 9. Layers surrounding Fibercables… Outer Jacket  To reduce abrasion and to provide extra protection against external mechanical strength Filler materials  To avoid moisture absorption by fibers  Prevents corrosion http://amitbiswal.blogspot.com
  10. 10. Layers of Fiber cables Jacket 400 µm Buffer 250 µm Cladding 125µm Core 8µm http://amitbiswal.blogspot.com
  11. 11. 1. Single Fiber cable Fiber is made from brittle glass Buffer jackets made of plastic Silicon coating between buffer jacket and optical fiber Final cover by black polyurethane http://amitbiswal.blogspot.com
  12. 12. 2. Multi fiber Cable Used in telecommunication Kevlar is used to provide tensile strength Outer sheath for protection against impact forces (forces generated due to brittleness) http://amitbiswal.blogspot.com
  13. 13. Advantages of optical fiberas waveguides Wider band-width Low transmission loss Signal security Small size & weight Flexibility Easy maintenance Low cost http://amitbiswal.blogspot.com
  14. 14. Materials used tomanufacture optical fibers Glass fibers Crystalline and fluoride fibers Plastic clad glass fibers Plastic fibers http://amitbiswal.blogspot.com
  15. 15. Application of opticalfibers Fiber optic delay lines  By using low loss optical fibers Fiber optic sensors  By utilizing external influences, like phase sensitivity, micro bending losses and modal noise Fiber endoscopes  Using large diameter and short length silica fibers http://amitbiswal.blogspot.com
  16. 16. Thank YouFind more athttp://amitbiswal.blogspot.com http://amitbiswal.blogspot.com