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 Telecom
conference & convention enabling the next generation of networks & services Presenter Profile Nicolas Brochier received his Master of Engineering degree in Optical Sciences in Place 1998 from SupOptic (Orsay - France). picture He joined the Orange Labs in 2001 to carry here out laboratory experiments on submarine out laboratory experiments on submarine transmission. He now conducts analytical 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
conference & convention enabling the next generation of networks & services Content 1 Context & Problematic 2 2 System Set Up System Set Up 3 Polarization Fluctuation Speed 4 40Gbit/s System Design Impact 5 Conclusion
conference & convention enabling the next generation of networks & services Context & problematic Performances fluctuations are a major issue for optical transmission systems � 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
conference & convention enabling the next generation of networks & services Context & Problematic Static versus Dynamic "mitigation" solution � at 10G , statistical provision is considered to ensure ATIC an outage probability lower than 6.10 -7 STAT well known 5 σ σ rule (Gaussian σ σ assumption) � at 40G , for LH submarine systems, the same DYNAMICS 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
conference & convention enabling the next generation of networks & services System Set-Up SOP measurement on SMW-3 S9 Penmarc'h Atlantic ocean France Sea-Me-We 3 – 1600 km long Seg. 9 – cable section below 500 m depth are buried Portugal – 50% of the cable lies Spain deeper than 4000 m Sesimbra
conference & convention enabling the next generation of networks & services System Set-Up SOP measurement on SMW-3 S9 (at Penmarc'h) Penmarc'h SLTE Penmarc'h SLTE DCM DCM Rx Rx From the DCM Rx submarine link DCM Rx Monitoring port Optical Pol. filter Analyzer 1559 nm 1 kHz sampling rate
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Average polarization fluctuation Polarization fluctuation speed – SOP is averaged over 1 minute and monitored during ~ 90 hours ~ 90 hours SOP fluctuation speed is defined SOP fluctuation speed is defined as the rotation angle ( deg ) on the – Relatively continuous average fluctuation S 3 Poincare sphere per time unit (t) SOP (t 1 ) SOP (t 2 ) angle(SOP t2 , SOP t1 ) ∆ SOP ∆ t = S 1 during ∆ t = t 2 -t 1 S 2
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Average polarization fluctuation – SOP is averaged over 1 minute and monitored during ~ 90 hours ~ 90 hours – Relatively continuous average fluctuation Number of occurences 600 SOP average fluctuation Very fast events speed ( ∆ SOP 1min ) ~ 6˚ / min 400 200 0 0 10 20 30 40 50 SOP fluctuation speed ( ∆ ∆ ∆ SOP 1min ) (degrees/min) ∆
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Identification of rapid events – 2 months SOP measurement with 1kHz time resolution resolution – the fastest fluctuation for each minute is recorded – Rapid Events are arbitrarily defined such as : Mean ∆ SOP 100ms ∆ SOP ∆ t > mean ∆ SOP ∆ t + 5 σ Mean + 5 σ Rapid with ∆ t = 1, 10, 100ms events
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Maximum fluctuation speed observed ∆ t 1ms 10ms 100ms mean ∆ SOP ∆ t + 5 σ mean ∆ SOP + 5 σ 2.3 ° 2.3 ° 4.3 ° 4.3 ° 10.3 ° 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?
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Origin of rapid events ? Time distribution of rapid events is analyzed using Fourier transform Fourier transform SOP Water height Tide's coef. 2,3.10 -5 Hz Tide's or night/day effect ? 8.10 -7 Hz Extracted from http://www.shom.fr/
conference & convention enabling the next generation of networks & services Polarization Fluctuation Speed Origin of rapid events ? Rapid events are clearly dependent on the Rapid events are clearly dependent on the tide's effect .
conference & convention enabling the next generation of networks & services 40Gbit/s System Design Impact At 40G, polarization fluctuation becomes problematic for LH submarine systems whatever the technology is. Dynamic devices or algorithms are required – 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
conference & convention enabling the next generation of networks & services 40Gbit/s System Design Impact At 40G, outage probability calculation should take into account: – the probability to exceed the speed of tracking capability 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
conference & convention enabling the next generation of networks & services Conclusion Field SOP fluctuations measurement over a 1600 km submarine system 2 Polarization fluctuation systems identified 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
2010 conference & convention enabling the next generation of networks & services The 7th International Conference & Convention on Undersea Telecommunications Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org
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