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Session 4: Termination and Splices

Session 4: Termination and Splices. FO Connectors Specifications. Specifications Loss Repeatability Environment (temp, humidity, vibration, etc.) Reliability Back reflection Ease of termination Cost. Connector Ferrules. Connector End Finishes. Connector Termination Processes.

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Session 4: Termination and Splices

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  1. Session 4: Termination and Splices

  2. FO Connectors Specifications • Specifications • Loss • Repeatability • Environment (temp, humidity, vibration, etc.) • Reliability • Back reflection • Ease of termination • Cost

  3. Connector Ferrules

  4. Connector End Finishes

  5. Connector Termination Processes • Epoxy/polish • Hot-melt (3M trademark) • Anaerobic • Crimp/Polish • Crimp/cleave • Mechanical Splice

  6. Termination - Adhesive/Polish Stripping The Fiber

  7. Connector Termination Applying Adhesive

  8. Connector Termination Crimping To The Cable

  9. Connector Termination Cleaving The Fiber

  10. Connector Termination “Air Polishing”

  11. Connector Termination Polishing

  12. Connector Termination Microscope Inspection

  13. Connector Termination Direct With Core Illuminated Angle View

  14. Fiber Optic Splices • Permanent terminations for fiber • Specifications • Loss • Repeatability • Environment • Reliability • Back reflection • Ease of termination • Cost

  15. Fiber Optic Splices

  16. Fiber Optic Splices - Fusion

  17. Fiber Optic Splices - Mechanical

  18. Fiber Optic Splices - Cleaving

  19. Connector & Splice Loss

  20. Back Reflection (Return Loss) • Light reflects at surfaces between materials of different indices of refraction • Glass to air interface yields about a 4% reflection • Occurs at fiber optic joints • Splices have lower back reflection due to fusing or using index matching fluid • Domed (PC) fiber end faces can minimize air to reduce back reflection

  21. Continuity Testing • With visual tracer or fault locator • Tracer is flashlight or LED • Fault locator uses visible red laser • Useful for verifying mechanical splices or prepolished/splice-type connectors

  22. Insertion Loss Testing • Simulates actual system operation

  23. OTDR Testing • OTDR testing

  24. OTDRs • OTDRs are valuable tools for testing fiber optics. They can verify splice loss, measure length and find faults. • used to create a blue print of fiber optic cable when it is newly installed. • Later, comparisons can be made between the "blue print" trace and a second trace taken if problems arise.

  25. OTDR Testing OTDRs work like "optical RADAR," sending out a test pulse and looking for return signals.

  26. OTDRs See Backscattered Light • Scattering is the primary loss mechanism in fiber • Some light is scattered back to the source • ~1 millionth of signal at 1310 nm • OTDR process • Send out high power signal • Gather backscatter light • Averages signal • Display backscatter signal over time

  27. Typical Result

  28. Information In The OTDR Display

  29. Fiber Attenuation and Distance Attenuation Coefficient = (Psource –Pend)[dB]/fiber length [km]

  30. 2-Point Loss

  31. Least Squares Loss

  32. Connector or Splice Loss By 2-Point Method

  33. Connector 2-Point Loss

  34. Connector or Splice Loss By “Least Squares”

  35. Connector Least Squares Loss

  36. Back Reflection (Optical Return Loss)

  37. Connector Reflectance

  38. OTDR Launch Cable Pulse Suppressor /Testing Initial Connector Testing Far End Connector

  39. OTDR Ghosts

  40. OTDR Pulse Width • Wider pulse = more energy = more range • But wider pulses mean less resolution • 1 us => 3x108 m/s x 1x10-6 s = 300 m • 1 ns => 3x108 m/s x 1x10-9 s = 0.3 m

  41. OTDR Resolution to see an event close to the OTDR; to see two events close together.

  42. OTDRs and Multimode Fibers • Laser test signal is smaller than core • Underestimates loss significantly • OTDR is no substitute for insertion loss test

  43. Good OTDR Traces

  44. Improving OTDR TracesUsing index matching fluid

  45. OTDR Measurement ParametersApproximate Settings • Wavelength (850/1300 MM, 1310/1550 SM) • generally do both wavelengths • Range (2 to 100+ km) • Set to greater than 2X cable length • Pulse width (10 m to 1 km) • Set as short as possible for best resolution • Averaging (1 to 1024 averages) • For short cables, 16-64 averages

  46. Range • A 5.2 km link taken at ranges of 2 km (green), 5 km (brown) and 10 km (blue).

  47. Wavelength • A single fiber at both 850 nm (green) and 1300 nm (blue) wavelengths.

  48. Pulse Width • A single fiber measured at shortest (blue), median (brown) and longest (green) pulse widths.

  49. With 30 ns and 90 ns Pulse Width 90 ns (equivalent to 18 m) pulse width) 30 ns (equivalent to 6 m) pulse width

  50. Averages no averaging averaged 1024 times

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