Field measurement of polarization fluctuation dynamic and impact - - PowerPoint PPT Presentation
conference & convention enabling the next generation of networks & services Field measurement of polarization fluctuation dynamic and impact for 40 Gbit/s submarine systems for 40 Gbit/s submarine systems Nicolas Brochier France
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Field measurement of polarization fluctuation dynamic and impact for 40 Gbit/s submarine systems for 40 Gbit/s submarine systems
Nicolas Brochier
France Telecom
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Presenter Profile
Nicolas Brochier received his Master of Engineering degree in Optical Sciences in 1998 from SupOptic (Orsay - France). He joined the Orange Labs in 2001 to carry
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and experimental studies on high bit rate submarine systems and provides support to France Telecom as a line design expert. Nicolas Brochier Research Engineer nicolas.brochier@orange-ftgroup.com Tel: (+33) 2 9605 0382
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Content
1 Context & Problematic 2 System Set Up 2 System Set Up 3 Polarization Fluctuation Speed 4 40Gbit/s System Design Impact 5 Conclusion
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Context & problematic
Performances fluctuations are a major issue for
mainly due to polarization effects mainly due to polarization effects provisions are added in the Power Budgets to take into account the Q-factor fluctuation at 10G, provision for performances fluctuation is usually of the same order of magnitude than the provision taken for transmission impairments
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Context & Problematic
Static versus Dynamic "mitigation" solution
at 10G, statistical provision is considered to ensure an outage probability lower than 6.10-7 ATIC well known 5σ σ σ σ rule (Gaussian assumption) at 40G, for LH submarine systems, the same approach implies dramatic provisions for PMD and hence dynamic compensation is required Characterizing the fluctuation of polarization in a submerged line becomes a key issue STAT DYNAMICS
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SOP measurement on SMW-3 S9
Penmarc'h Atlantic ocean
System Set-Up
– 1600 km long – cable section below 500 m depth are buried – 50% of the cable lies deeper than 4000 m
Sesimbra France Portugal Spain Sea-Me-We 3
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System Set-Up
SOP measurement on SMW-3 S9 (at Penmarc'h)
DCM Rx
Penmarc'h SLTE From the submarine link
DCM Rx Optical filter Pol. Analyzer DCM Rx DCM Rx
Penmarc'h SLTE Monitoring port 1559 nm 1 kHz sampling rate
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Average polarization fluctuation
– SOP is averaged over 1 minute and monitored during ~ 90 hours
Polarization Fluctuation Speed
Polarization fluctuation speed
SOP fluctuation speed is defined ~ 90 hours – Relatively continuous average fluctuation SOP fluctuation speed is defined as the rotation angle (deg) on the Poincare sphere per time unit (t)
S1 S2 S3 SOP (t1) SOP (t2)
∆SOP∆t = angle(SOPt2 , SOPt1) during ∆t = t2-t1
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Average polarization fluctuation
– SOP is averaged over 1 minute and monitored during ~ 90 hours
Polarization Fluctuation Speed
~ 90 hours – Relatively continuous average fluctuation SOP average fluctuation speed (∆SOP1min) ~ 6˚ / min
600 400 200 00 10
20 30 40 50
Number of occurences SOP fluctuation speed (∆ ∆ ∆ ∆SOP1min) (degrees/min)
Very fast events
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Identification of rapid events
– 2 months SOP measurement with 1kHz time resolution
Polarization Fluctuation Speed
resolution – the fastest fluctuation for each minute is recorded – Rapid Events are arbitrarily defined such as :
Mean ∆SOP100ms Mean + 5σ Rapid events
∆SOP∆t > mean ∆SOP∆t + 5σ with ∆t = 1, 10, 100ms
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Maximum fluctuation speed observed
Polarization Fluctuation Speed
∆t 1ms 10ms 100ms mean ∆SOP + 5σ 2.3° 4.3° 10.3° mean ∆SOP∆t + 5σ 2.3° 4.3° 10.3° Detected events during 2 months monitoring Rapid Events count 29 503 363 ∆SOP∆t max 19.9° 37.6° 82.5°
Highest value observed
Where do these Rapid events come from?
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Origin of rapid events ?
Time distribution of rapid events is analyzed using Fourier transform
Polarization Fluctuation Speed
Fourier transform
2,3.10-5 Hz
SOP Water height
Extracted from http://www.shom.fr/
Tide's or night/day effect ?
8.10-7 Hz
Tide's coef.
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Origin of rapid events ? Rapid events are clearly dependent on the
Polarization Fluctuation Speed
Rapid events are clearly dependent on the tide's effect.
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At 40G, polarization fluctuation becomes problematic for LH submarine systems whatever the technology is. Dynamic devices or algorithms are required
40Gbit/s System Design Impact
– for PMD mitigation – for polarization demultiplexing (source diversity) 40G should be characterized in dynamic conditions Dynamic conditions should be specified to meet at least ∆ ∆ ∆ ∆SOP up to 20˚/ms
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At 40G, outage probability calculation should take into account: – the probability to exceed the speed of tracking capability
40Gbit/s System Design Impact
capability – the time required to restore the convergence of dynamic algorithms in case of loss – the errors statistics modification over the FEC correction ability Margins computation for QTSVP may need to be reviewed
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Field SOP fluctuations measurement over a 1600 km submarine system 2 Polarization fluctuation systems identified
Conclusion
2 Polarization fluctuation systems identified
– quasi continuous around 6 ˚/ms – rapid events correlated to tide's effect up to 20 ˚/ms
System design impact :
– 40G equipments should be specified and qualified in dynamic conditions – outage computation should be revisited and experimentally assessed
enabling the next generation of networks & services
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Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org The 7th International Conference & Convention