Scattering and bending loss 18 19

EC6702 Optical Communication and Engineering

1. EC6702 OPTICAL COMMUNICATION AND
NETWORKS

2. Scattering Losses

3. Scattering Losses
Density Composition

4. Scattering Losses
Density Composition

5. Scattering Losses

6. Scattering Losses
•Linear Scattering Losses
1.Rayleigh Scattering Losses
2. Mie Scattering Losses

•Non –Linear Scattering Losses
1. Stimulated Brillouin Scattering
2. Stimulated Raman Scattering

7. Scattering

8. 1.Rayleigh Scattering Losses
•Micro Variation in Material Density


•Composition Density

9. Fiber Manufacturing

10. Fiber Manufacturing
•Slight Fluctuation in mixing of Ingredients.
•Impossible to eliminate.
•Slight changes in density of Silica cools and
Solidifies.

11. Scattering depends on Size of the fiber material
discontinuity

12. Scattering loss for single component
glass is,

13. Single Mode vs Multi Mode
•Core Material Highly Dopped Concentrated
material.

14. •High Compositional Fluctuation.
•.. So, Multi Mode fibers having the more
losses.

15. 2.Mie Scattering
•In Homogeneous
•Imperfection
•Fiber Geometry (shape)
•Irregularity of Refractive Index
•Bubbles

16. Avoid.,
•Careful Manufacturing

17. Non Linear Scattering losses
•Depends on Optical Power Density
•Power Transfer in Forward or Backward
directions depends on frequency.
•Threshold power level  High Frequency

19. Stimulated Brillouin Scattering(SBS)
•Thermal molecules Vibration

20. Thermal molecules Vibration

23. Stimulated Raman Scattering(SRS)
•High frequency optical photons generated.
•Forward or Backward directions.

25. Bit Rate BT ≤ 1/2T

26. Bending Loss
Changes in radius of the curvature

27. When an optical fiber undergoes bending is
called – Bending Loss.

28. Sharp bending - Radiative loss – Microscopic
variation and Macroscopic variation

29. Critical Angle - Escape

30. Avoid, Bending

31. Micro bending
•Small distortion
•Not Visible
•Temperature / Tensile / Crush related
•Couple

Testing & Installation 

32. Macro bending
•Large spectral Variation
•In Multi mode fiber  Attenuation

33. In Multimode Fiber, effective number of modes that can be
expressed by,

34. Core and Cladding Loss
•Different Material (elements), Density,
Composition.
•Different Attenuation co-efficient (α
1 & α2).

•Lower order vs Higher Order

37. Distortion Loss
•Spectral Width
•Pulse Broadening

39. Distortion Loss
•Inter Modal Dispersion (Multi Mode)
•Intra Modal Dispersion (Single Mode)
•Group Velocity Dispersion
•Chromatic Dispersion

High energy speed of light in different modes

40. Chromatic Dispersion

41. Types of Intra Modal Dispersion
•Material Dispersion (Variation of RI of Core)
•Wavelength Dispersion (SM fiber 80% power in
core & 20% power in cladding)

•LED 1550nm SM
•MM different velocity waves

42. Material Dispersion (Variation of RI of Core)

43. Wavelength Dispersion

44. Information Capacity Determination

45. Information Capacity Determination
•Information Calculation
•Adjacent pulse coincidences

•Bandwidth Distance Product (BL) (Unit)
•MHz/Km
• SM = 20 MHz
•MM = λ (we are selected)

46. Thanks for Your Attention