Formation sur le réseau optique pour les débutants. Ce document vous apprend les bases fondamentale du réseau et de la fibres optiques

1. OPTICAL NETWORKS
LECTURES 1, 2, 3 & 4
DATE : 09/22/2016
TIME: 08: 00 – 12: 15
BY: K. B BLA, LECTURER IN
TELECOMMUNICATIONS
1

2. OPTICAL NETWORKS
An Optical Network is a Broadband and
High Capacity Telecom Network, which
is fully or almost fully interconnected by
Optical Fiber cables
The core of such a network always uses
optical fibers as its transmission medium.
The Access Network is partially or fully
linked by optical fibers
Almost the core of all broadband
networks are currently using optical
fibers and optical fibers will still be the
best transmission medium for many years
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3. ADVANTAGES OF OPTICAL
FIBERS
• + Wide Bandwidth (up to 3.7 THz)
• + Low attenuation ( less than 1
dB/km).
• + Immunes to cross-talk,
interferences
• + Resistant to hazards &
environmental attacks
• + Long Distance Transmission
• + Low cost (medium or long term)
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4. DISADVANTAGES OF OPTICAL
FIBERS
• - High initial cost
• - Non Linear effects
• - Very fragile so maintenance & repairs
costs are high
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5. PRINCIPLES &
CHARACTERISTICS
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Figure 1: Optical Fiber
Profile

6. PRINCIPLES &
CHARACTERISTICS
The light is guided inside the fiber by
successive reflections. But this can
happen only if some conditions are met
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7. CRITICAL ANGLE
The critical angle can be defined as the
minimum angle of incidence at which the
angle of refraction is equal to 90 deg
For TIR to occur, the angle of incidence
must be larger than the critical angle
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8. NUMERIOCAL APERTURE
The NA is intended as a measure of
light capturing ability of a fiber
the higher the NA, the better the
fiber can sustain bending & the
greater the dispersion
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9. DISPERSION
Dispersion is the spreading of pulses
in time that is caused by the
following facts:
 Power of a pulse travelling through a fiber
is dispersed in time
 Different spectral components a signal
travel at different speeds
 Results from different phenomena
3 types of dispersion:
 Inter – modal disp (in multimode fibers)
 intra – modal disp ( in single &
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10. INTER - MODAL DISPERSION
.
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11. INTER – MODAL DISPERSION
.
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12. INTER-MODAL DISP IN GRADED
INDEX MMF
.
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13. INTER-MODAL DISPERSION
.
then the fundamental limitations
over a MMF is measured by its
product, expressed in
It represents the capacity of the
MMF
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14. INTRA-MODAL DISPERSION
.
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15. MATERIAL DISPERSION
.
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16. MATERIAL DISPERSION
.
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17. MATERIAL DISPERSION
.
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18. MATERIAL DISPERSION
.
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19. WAVEGUIDE DISPERSION
.
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20. SPOT SIZE
For a Gaussian beam
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21. TOTAL DISPERSION
.
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22. TUNING DISPERSION
.
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23. DISPERSION RELATED
PARAMETERS
.
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24. POLARIZATION MODE
DISPERSION
.
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25. EFFETS OF DISPERSION : PULSE
SPREADING
.
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26. EFFETS OF DISPERSION :
CAPACITY LIMITATION
.
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27. ATTENUATION
.
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28. ATTENUATION
.
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29. COUPLER & CONNECTOR LOSSES
.
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30. LOSSES DUE TO LATERAL
MISALIGNMENT
.
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31. LOSSES DUE TO LATERAL
MISALIGNMENT
.
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32. LOSSES DUE TO LATERAL
MISALIGNMENT
.
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33. LOSSES DUE TO LATERAL
MISALIGNMENT
.
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34. END SEPARATION LOSS
.
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35. END SEPARATION LOSS
.
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36. END SEPARATION LOSS
.
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37. END SEPARATION LOSS
.
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38. END SEPARATION LOSS
.
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39. PRINCIPLES &
CHARACTERISTICS
.
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40. LOSS DUE TO FIBER CORE
DIFFERENCE
.
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41. LOSS DUE TO FIBER CORE
DIFFERENCE
.
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42. MODES IN OPTICAL FIBERS
.
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43. MODES IN OPTICAL FIBER
The number of modes is related
to the normalized freq
For SMF
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44. MODES IN OPTICAL FIBERS
.
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45. OPTICAL COM LINK
.
.
The role of the com channel is to
carry the optical signal from TX to
RX without distorting it
Com Channel = Optical Fiber
Figure : Generic optical
Com System
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46. OPTICAL TRANSMITTER
(a)
(b)
Figure : Optical TX (a) Components
(b) Equivalent system
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47. OPTICAL TX
The role of an optical TX is to
convert the electrical signal into
optical form and launch the resulting
optical signal into the optical fiber
Optical Source = Semiconductor
Laser or LED
The optical signal is generated by
modulating the optical carrier wave
The optical coupler is micro lens
that focuses the optical signal onto
the entrance plane of an optical fiber
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48. LED
Bandgap Energy: depends on the
type of alloy. For a quaternary
alloy:
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49. LED
Quantum Efficiency
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50. LED
Optical Power
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51. LASER
Optical Gain at Threshold
.
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52. OPTICAL RX
Figure : Optical RX (a) Components
(b) Equivalent system
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53. PHOTODIODE
Quantum Efficiency
Responsivity
.
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54. PHOTODIODE
RX Sensitivity
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55. TELECOMS NETWORK
Figure : Public
Network
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56. TELECOMS NETWORK
The nodes in the network are
called Central Offices (CO) or
Points of Presence (PoP)
The Metro or Interoffice Network
lies within a large city or region
and interconnects groups of COs
in that city or region. Typically, its
spans a few km to several tens of
km between COs
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57. Access Networks
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58. RESEAUX OPTIQUES
.
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59. OPTICAL NETWORKS
.
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60. OPTICAL NETWORKS
.
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61. OPTICAL NETWORKS
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62. OPTICAL NETWORKS
.
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