SUBMARINE SYSTEMS

1
SUBMARINE SYSTEMS THEORY CONCEPTS
2
SUBMARINE SYSTEMS RD BASICS OF OPTICAL
TRANSMISSION
3
OPTICAL COMMUNICATION SYSTEM
4
OPTICAL AMPLIFICATION
5
OPTICAL AMPLIFICATION - PRINCIPLES
EXCITED STATE
METASTABLE STATE
STABLE STATE
6
OPTICAL AMPLIFICATION WDM
Amplified Spontaneous Emission Noise
7
SIGNAL TO NOISE RATIO
Peak signal power (Ps)
SNRO
Noise power (PASE_SX)
Noise power (PASE_DX)
?
8
BIT ERROR RATE AND Q FACTOR
The transmission quality of a digital
communication system is related to the BER (Bit
Error Rate). In optical communications, it is
common to use the Q factor figure of merit
Sampling region
2?1
I1
Decision threshold
Id
I0
2?0
9
SUBMARINE LINK PERFORMANCE
The Q factor (and consequently the BER) depends
on the link SNRo, that is the key design factor
for submarine links
10
SUBMARINE SYSTEMS RD LINEAR PROPAGATION
EFFECTS
11
GAIN EQUALIZATION - SHAPE
Amplifier shape
12
GAIN EQUALIZATION - TILT
13
GAIN EQUALIZATION - SOLUTIONS
14
CHROMATIC DISPERSION (GVD)
15
CHROMATIC DISPERSION AND SLOPE
GVD
SLOPE
16
CHROMATIC DISPERSION - COMPENSATION
NZD
SMF
17
DISPERSION MAP
18
POLARIZATION MODE DISPERSION - PMD

• Difference of propagation of the principal states
  of light polarization
• causes
• Optical components birifringency
• Optical fibre birifringency
• effects
• penalty on Q-factor lt 0.1dB if ?T lt 0.08 Tbit
  (8ps _at_10Gb/s)
• Typical values
• amplifiers lt 0.30.5 ps
• fiber lt 0.1 ps/?km

19
SUBMARINE SYSTEMS RD NON-LINEAR PROPAGATION
EFFECTS
20
FIBER NON-LINEARITY
The field intensity is directly related to the
launched optical power. The non-linearity
combines with the GVD and distorting the
transmitted signal. The most relevant effects
are Self-Phase Modulation (SPM), Cross-Phase
Modulation (XPM) and Four-Wave Mixing (FWM)