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8/3/2019 Fibra ptica - evolucin de estndares
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22 Jan 2010
Update on optical fiber and cable
standards
Daniel Daems
Tyco ElectronicsBelgium
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Slide 2Daniel Daems March 2010
Most relevant standardization bodies
Leading standardization bodies for:
Fibers: ITU-T SG15:
G650 test method series G651 multimode 50/125 m G652 dispersion unshifted singlemode optical fiber G653 dispersion shifted singlemode optical fiber G654 cut-off shifted singlemode optical fiber G655 non-zero dispersion-shifted singlemode optical fiber
G656 non-zero dispersion-shifted singlemode fiber for wideband optical transport G657 bending loss insensitive singlemode optical fiber
Recent changes seen in G657 for low bend loss fibers
FO Cables: IEC SC86A
60793 series for fibers 60794 series for cablesRecent changes seen in patchcord cables IEC 60794-2-50
TELCORDIA GR 20
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Slide 3Daniel Daems March 2010
Low Optical Bend Loss Fibers
Why needed?
Cable attachments with staples!?
Corners
Staples
According to Verizon the radius around corners and under staples can go down to 5 mm!
Smaller boxes and wall
outlets with fiber bend
radius 20 mm
Sharp bends
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Slide 4Daniel Daems March 2010
Bending loss performance of standard singlemode fiber (ITU-T G. 652D)
Low Optical Bend Loss Fibers
Radius Loss increaseG.652 matched
30 mm < 0.05 dB
25 mm < 0.05 dB20 mm < 0.05 dB15 mm 0.49 dB
10 mm 17.3 dB
1625 nm results
Radius 10 mm
Radius 15 mm
Radii 20 mm
Spectral macrobending loss of SMF 28 fiber for 10 loops
0
0.4
0.8
1.2
1.6
2
2.4
2.8
3.2
3.6
4
1250 1300 1350 1400 1450 1500 1550 1600 1650
Loss(indB)
Wavelength (in nm)
MFD (1310 nm) : 8.9m ...9.5m
R
Observations: Loss becomes important once bending radius becomes smaller than 20 mm Splicing trays with 25 mm and 30 mm bending radius will not affect transmission at 1625 nm
in G. 652D fibers In some limited cases (max 2 meter) a 20 mm radius is allowed (see ITU-T L13 and IEC
61756)
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Slide 5Daniel Daems March 2010
R
nRefractive index profile:
Characteristics:
General:
Optimized bandwidth for 1310 nm transmission(= Minimum chromatic dispersion at 1310 nm)
Lowest attenuation at 1550 nm
Mode field diameter at 1310 nm: 9.2 m 0.4 m
Mode field diameter at 1550 nm: 10.4 m 0.5 m
Cladding diameter: 125 m 0.7 m
Mode field concentricity error: 0.5 m @ 1310 nm
1550 nm loss performance: < 0.05 dB for 100 turns
on 50 mm mandrel diameter
Chromatic dispersion:
3.5 ps/(nm.km) @ 1310 nm 18 ps/(nm.km) @ 1550 nm
Proofstress strain test: 1%Attenuation:
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Slide 6Daniel Daems March 2010
R
n
Refractive index profile:
Characteristics (not up-to-date!):Mode Field Diameter at 1310 nm: 8.8 m 0.5 m
Mode field diameter at 1550 nm: 9.7 m 0.6 m
Cladding diameter: 125 m 1.0 m
Mode field concentricity error: 0.8 m @ 1310 nm
PMD (fiber): 0.5 ps/km at 1310 nm
Chromatic dispersion: 18 ps/(nm.km)at 1550 nm1550 nm loss performance: < 0.1 dB for 100 turns
on 75 mm mandrel diameterProofstress strain test: 1%Attenuation:
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Slide 7Daniel Daems March 2010
How can you improve the bending loss performance?
Light in a waveguide is better contained when the difference of
refractive index between the core and cladding is increased.
This results in a better bend loss performance, but it will result in a
lower bandwidth or transmission capacity (modal dispersion, higher
chromatic dispersion)
Low Optical Bend Loss Fibers
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Slide 8Daniel Daems March 2010
Radius
Refractive index
Radius
Refractive index
Radius
Refractive index
Radius
Refractive index
Matched claddingsinglemode fiber (standard)
Depressedcladding singlemode fiber
Trench assisted
Ring assistedsinglemode fiber
A lower refractive index can beachieved by fluor doped solid glass orby air-holes in glass
Examples Hole Assisted Fiber (HAF):
Betterbendlos
sperformance
Different low microbend loss fiber types
Low Optical Bend Loss Fibers
!
The mechanical reliability remainsthe same for all these 125/250 mfibers since the cladding andcoating has not changed!
Radius
Refractive index
Hole assisted
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Slide 9Daniel Daems March 2010
Low Optical Bend Loss Fibers
ITU has published in Dec 2006 a recommendation for such fibers:
ITU-T G.657A fiber: These are G. 652D fibers with tighter dimensional tolerances
that will result in a better optical performance during bending. These fibers are also
known as Low Macrobend Loss fibers. The specifiedminimum bending radius for
optical attenuation is 10 mm. Roughly 10 times better bending performance than
traditional single-mode fiber
ITU-T G.657B fiber: Fibers designed to have a very low loss during bending, but
they are not always compatible with the G. 652 fibers anymore and thereforerestricted to shorter distances (associated with indoor cabling). These fibers can
have connection and splicing problems for some types. These fibers are typically
called Bend Tolerant Fibers. The specifiedminimum bending radius for optical
attenuation is 7.5 mm. Roughly 100 times better bending performance than
traditional single-mode fiber
ITU-T G. 657 recommendation
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Slide 10Daniel Daems March 2010
Installation inside houses:
Assume cable is routed though 3 rooms on the 1st floor:
This results in about 15x 90turns around a corner When nails or staples are used every 30 cm, about 70 staples will be used in this example.
Assume that each staple or nail creates a bend with radius 5 mm over 15 In total 2 meter of fiber is stored in the floor distribution box and wall terminal with radius 15 mm
7 m
1 m
5 m
5 m4 m
Total
probability:
2 meter
0,1 meter
0.125 meter
Length fiber
under stress
20 x 360(15 mm)
70 x 15(5 mm)
15 x 90(5mm)
Number of turns
Boxes
Staples
Corners
Item
10-5
3. 10-5
8.10-6
10-5
Probability
failure over 25
years
Low Optical Bend Loss Fibers
Mechanical reliability concerns
Important: In this casethe estimated contribution ofbending loss will be 1 dB at1550 nm and 3 dB at 1625 nmfor a G 657 B3 fiber!
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Slide 11Daniel Daems March 2010
Low Optical Bend Loss Fibers
Issues seen with bend insensitive fibers
Some fusion splicing machines do not recognize the
core of the new fibers and will not perform a core
alignment (switch to cladding alignment to solve this)
Hole assisted fiber types give problems during fusion
splicing (unexpected and unpredictable deformations).
Fluids may enter the holes when cleaning the fiber
ends with alcohol
Higher losses seen when different fiber types arespliced or connected together (mode field diameter
mismatch with most G. 657B type fibers). Losses
above 1 dB can be seen!
Insertion Loss = - 10 Log10 [ 4 ( + ) ]Rt
Rt
RR
- 2RR
Rt and RR = Mode Field Radii of connected fibers
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Slide 12Daniel Daems March 2010
Low Optical Bend Loss Fibers
Issues seen with bend insensitive fibers
OTDR traces will show strange effects (gainers or higher losses) when mixing fiber
types in connections or splices! Non-trained installers might make wrong
conclusions about the splice loss or connector loss quality!
OTDR652 652652652 652
Distance
Loss
Distance
Loss
OTDR
652 657652657 652
Loss seems high
Loss seems high
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Slide 13Daniel Daems March 2010
IEC fiber standards
IEC SC86A Working group 1 (fibers)
Mainly copy of ITU-T G6xx fiber documents for the singlemode fibers, but IEC
86A is the leader for the multimode fiber specifications.
Fiber standards Title60793-1-1 Optical fibres - Part 1-1: Measurement methods and test procedures - General and guidance
60793-2-10Optical fibres - Part 2-10: Product specifications - Sectional specification for category A1 multimodefibres
60793-2-20Optical fibres - Part 2-20: Product specifications - Sectional specification for category A2 multimodefibres
60793-2-30Optical fibres - Part 2-30: Product specifications - Sectional specification for category A3 multimode
fibres60793-2-40
Optical fibres - Part 2-40: Product specifications - Sectional specification for category A4 multimodefibres
60793-2-50 Optical fibres - Part 2-50: Product specifications - Sectional specification for class B single-mode fibres
60793-2-60Optical fibres - Part 2-60: Product specifications - Sectional specification for category C single-modeintraconnection fibres
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Slide 14Daniel Daems March 2010
Cable standards Title
60794-1-1 Optical fibre cables - Part 1-1: Generic specification - General60794-1-2 Optical fibre cables - Part 1-2: Generic specification - Basic optical cable test procedures60794-2 Optical fibre cables - Part 2: Indoor cables - Sectional specification
60794-2-10 Optical fibre cables - Part 2-10: Indoor cables - Family specification for simplex and duplex cables60794-2-11
Optical fibre cables - Part 2-11: Indoor cables - Detailed specification for simplex and duplex cablesfor use in premises cabling
60794-2-20Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical distributioncables
60794-2-21Optical fibre cables - Part 2-21: Indoor cables - Detailed specification for multi-fibre opticaldistribution cables for use in premises cabling
60794-2-30 Optical fibre cables - Part 2-30: Indoor cables - Family specification for ribbon cables
60794-2-31 Optical fibre cables - Part 2-31: Indoor cables - Detailed specification for optical fibre ribbon cablesfor use in premises cabling
60794-2-40 Optical fibre cables - Part 2-40: Indoor optical fibre cables - Family specification for A4 fibre cables
60794-2-50Optical fibre cables - Part 2-50: Indoor cables - Family specification for simplex and duplex cablesfor use in terminated cable assemblies
IEC SC86A Working group 3
Leading group for cable "family specifications". In fact a set of test is
standardized, but the severities can be freely chosen between the
manufacturer or customer in the detail specifications. As a result, there are noreal worldwide "cable standards" existing for pigtail cables or other cables!
IEC cable standards
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Slide 16Daniel Daems March 2010
Low Optical Bend Loss Fibers
Conclusions
ITU-T G.657 A1 and A2 fibers are gaining market share in the distribution
part of the network (till the wall outlet). For indoor cabling the G 657 B types
might be considered as well. Watch out! Cable manufacturers can misuse the advantages of bend
improved fibers for making lower quality cables! Specifications should be
carefully updated to avoid more cable end interface issues.