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7/28/2019 Fiber Types
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0.1
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800600 1200100016001400 1800
Early 1970s
First
Window
Second
Window ThirdWindow
1980s
Wavelen th nm
A t t e n u
a t i o n ( d B / k m
)
EVALUATION
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Mostly SM fiber is used long distance communication typically 5 Km
to 170 Km with out any problem
MM fiber is only used for the low data rates and short distance
communication typically 100 meter to 1 Km
Distance of reach depends on so many parameters
7/28/2019 Fiber Types
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Normal Single Mode Fiber
DSF (Dispersion shifted fiber)
NZ-DSF ( dispersion shifted fiber ) DCF (Dispersion compensating fiber)
LEAF (Larger effective area fiber)
DFF (Dispersion Flattened Fiber)
7/28/2019 Fiber Types
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Dispersion is zero at 1312 nm wavelength
At 1312 nm the losses in the fiber is high
While Losses minimum at 1550 nm while the dispersion
parameter is +17 ps/nm/Km
7/28/2019 Fiber Types
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Zero dispersion wavelength (nm)
Cutoff wavelength (nm)
Attenuation (dB/Km)
Dispersion (ps/nm Km)
PMD coefficient (ps/Km1/2)
Mode field diameter (micro meter)
Effective area (micro meter 2)
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Parameter at different wavelengths are
Attenuation slope (dB/Km/nm)
Dispersion slope (ps/nm2 Km)
Mode field diameter
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1 Attenuation only in fiber (dB/km) 1550 nm ≤0.25
2 Attenuation vs. wavelength (dB/km) 0.05
Max Delta from 1550nm value between (1525-1625 nm)
3 Dispersion slope (ps/nm 2 -km) mean At 1550 (nm) ≤ 0.092
4 Zero dispersion wavelength (nm) 1310 or 15505 Dispersion (ps/nm.km) mean @1550nm (P or N)
1530 to 1565 nm 2.6 to 6.0 P
1565 to 1625 nm 4.5 to 11.2 P
6 Mode field diameter (µm) At 1550 nm 9.2 to 10
7 Max Effective area (µm2) Norminal 72
8 Cutoff Wavelength (nm) 1247
9 PMD Coefficient (ps/km1/2), max mean, @1550 nm ≤0.08
10 Effective Group Index of Refraction @ 1550 nm 1.469
7/28/2019 Fiber Types
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G.650 – Definition and test methods for the relevant
parameters of single mode fibers
G.651 – Characteristics of a 50/125 μm multimode graded
index optical fiber cable
G.652 – Characteristics of a single-mode optical fiber cable
G.653 – Characteristics of a dispersion-shifted single-mode
optical fiber cable.
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G.654 – Characteristics of a 1550 nm wavelength loss-
minimized single-mode optical fiber cable
G.655 – Characteristics of a non-zero dispersion single- mode
optical fiber cable.
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ITU-recommendation G.652 SMF has
Zero chromatic dispersion at 1310
High chromatic dispersion
(approx. 17ps/nm-km) at 1550nm Advantage
Support WDM
Low in cost Disadvantage
Suitable only for short and medium distances
Needs Dispersion Compensation modules
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15501310
D i s p e r s i o n ( p s / n m . K m )
0
-10
-20
10
20
nm
EDFA Gain Spectrum
1530 1610
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ITU-recommendation G.653
Wave guide dispersion and material dispersion cancel out each other at1310nm
Same cancellation is used at 1550nm band
The reasons are principally:
Fiber attenuation is a lot lower in the 1550 nm band
Erbium doped fiber amplifiers operate in this band Done by increasing the waveguide dispersion
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1550
1310
D i s p e r s i o n ( p s / n m . K
m )
0
-10
-20
10
20
nm
EDFA Gain Spectrum
1530 1610
NDSF
DSF
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Advantage
Suitable for DWDM applications, with broad channel
spacing
Dispersion compensation is required after long distances
Disadvantage
Not suitable for higher channel count
Suffers from strong nonlinear effectsUnsuitable for narrow channel spacing, due to four wave
mixing
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• ITU-recommendation G.655
• Low positive value of dispersion
(4 ps/nm/km in the 1530-1610 nm band)
• Advantages
• Minimizes unwanted effects Four-Wave-Mixing(FWM)
• More distance than SMF
• Disadvantage
• Not able to carry large optical power
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D i s p e r s i o n ( p s / n m . K
m )
0
-5
-10
5
10
nm
EDFA Gain Spectrum
1530
1610
NZ-DSF
DSF
1550
NZ-DSF
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• Here dispersion over range from 1300 to 1700 is reduced i.e 3ps/nm/km
• Advantages
• Very less dispersion change within EDFA spectrum
• Efficient for DWDM systems with less number of channels • Disadvantages
• Extremely high attenuation (2dB/Km)
• Severe Four Wave Mixing problems
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D i s p e r s i o n ( p s / n m . K
m )
0
-10
-20
10
20
nm
EDFA Gain Spectrum
1530 1610
DSF
1550
Dispersion
Flattened
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Fiber effective is increased to 72 to 80 micro meter 2 from 50 micro
meter 2
This type of fiber can carry large amount of the optical power
Nonlinear interactions will be reduced
Generally used in Undersea applications
Disadvantage
– Difficult fiber design
– Cost is very high
7/28/2019 Fiber Types
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Fiber Type Properties TargetApplication
NetworkImpact
SMF
NZDSF
LEAF
All-Wave™
RNDF
Standard
Reduced
Dispersion
Reduced Fiber
Non Linearity
Eliminates
Water Peak
Reduced Negative
Dispersion
Common
WDM Long
Haul
WDM Long
Haul
WDM Metro
CWDM
Metro,
Regional
-----------------
Reduced No. of
Regenerators
Reduced No. of
regenerators
Increased No. of
Usable & Low
Cost Components
Reduce DCMs &
Regenerators
Fiber Technologies