Fibers for Next Generation High Spectral Efficiency Undersea Cable - - PowerPoint PPT Presentation

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Fibers for Next Generation High Spectral Efficiency Undersea Cable - - PowerPoint PPT Presentation

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conference & convention enabling the next generation of networks & services Fibers for Next Generation High Spectral Efficiency Undersea Cable Systems Neal S. Bergano and Alexei Pilipetskii Tyco Electronics Subsea Communications

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SLIDE 1 enabling the next generation of networks & services

conference & convention

Fibers for Next Generation High Spectral Efficiency Undersea Cable Systems

Neal S. Bergano and Alexei Pilipetskii

Tyco Electronics Subsea Communications

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SLIDE 2 enabling the next generation of networks & services

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Presenter Profile

Alexei Pilipetskii Director - System Modeling & Signal Processing Research email: apilipetskii@subcom.com Tel: 732-578-7533 Alexei Pilipetskii received his M.S degree in physics from Moscow State University in 1985. From 1985 to 1994 he worked at the General Physics Institute in Russia. He received his Ph.D. in 1990 for research in nonlinear fiber optics. From 1994 to 1997 he was with the University

  • f Maryland Baltimore County, where his

interest shifted to fiber optic data

  • transmission. Since 1997 he has been

with SubCom, where he works on a number of research and development

  • projects. He is currently the director of a

research group focusing on next generation technologies for undersea transmission systems.

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Fibers for Next Generation High Spectral Efficiency Undersea Cable Systems

  • The importance of new “linear”

fiber types

  • Dispersion management in transoceanic length

cable systems

– 10G DPSK transmission

  • High spectral efficiency systems:

– Will require polarization multiplexed formats – The DP-PSK format with coherent receivers

  • Transmission Fiber “Figure-Of-Merit”

(FOM)

  • New transmission results
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Advances in Technology – New Fiber Types are Important!

Year

2.5 5 10 40 100 160 320 640 1,800 2,560 3,730 6,000 1 10 100 1000 10000 100000 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012

Experimental Transmission Capacity (Gb/s)

O p t i c a l A m p l i f i e r s W D M D i s p e r s i

  • n

M a n a g e m e n t a n d N Z D S F G a i n E q u a l i z a t i

  • n

F E C T r a n s m i s s i

  • n

F

  • r

m a t s H y b r i d A m p l i f i e r s D i s p e r s i

  • n

F l a t t e n e d F i b e r C

  • h

e r e n t R e c e i v e r s & L a r g e A r e a F i b e r s D + F u l l C

  • B

a n d A m p l i f i e r s

155x100G in 60nm

L a r g e A r e a N Z D S F L a r g e A r e a D + F i b e r

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Why Fibers are So Important: Linear and Nonlinear Transmission

Ref: Golovchenko, E.A., et. al. , OFC 1999, paper ThQ3

Q (dB) Relative pre-emphasis (dB)

  • 3

3 12 13 14 15 16 17 18 experiment simulation

OSNR limited Nonlinearity limited

  • One of the first Q vs. power curves published: 16x10Gb/s at 7500 km
  • Nonlinearity limits achievable performance (Q-factor), distance and

spectral efficiency

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Fibers and Dispersion Management

  • First optically amplifier systems were not designed to support WDM

– Transmission at or close to zero dispersion

  • Deep dispersion management:

– NZDSF with SMF Suppressed nonlinear effects between WDM channels – Further improvement: large effective area NZDSF (~ 70 m2) – 10 Gb/s bit rates, OOK signals, true WDM transmission

  • Dispersion slope compensated systems

– Increased transmission bandwidth – Large effective area SMF (~105 m2)

Ref: A. Gnauck, et al; IEEE JLT, vol. 26, 2009, p1032 N.S. Bergano, IEEE JLT,”

  • Vol. 23, 2005, p 4125
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NZDSF Dispersion Map

Large Area NZDSF NZDSF SMF

~ 500 km

~ 500 km

Large Area NZDSF 70m2 0.1ps/km -nm 2 NZDSF 55m2 0.07ps/km -nm 2

Wavelength Dispersion SMF NZDSF Large Area NZDSF Total Large Area NZDSF NZDSF

  • True WDM map

– Performance may vary with dispersion within the transmission band

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Dispersion Flattened Map

D+ D- D+ D- D+

~ 500 km

~ 500 km

Wavelength Dispersion

D+ D-

Total

D+ 75/110 m2 D- 25-35 m2

  • Increased linearity

– Performance equalized across transmission bandwidth

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10G DPSK Transmission in NZDSF Dispersion Map

  • Properly-built dispersion map optimizes performance

Transmission simulation: 9000 km Ref: W. Anderson, et. al., OFC 2005, OthC1 Experiments: 13000 km, Ref: J.-X. Cai., et. al., OFC 2004, PDP34

9 10 11 12 13 14 15 16 1535 1540 1545 1550 1555 1560 1565 Wavelength (nm) Q factor (dB) Large dispersion RZ-DPSK RZ-OOK Low dispersion Large dispersion

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Modulation format RZ-OOK (10 Gb/s) RZ-DPSK (10 Gb/s) Channel spacing 33 GHz 33 GHz Fiber plant Dispersion Flattened Fibers (DFF) DFF Amplifier spacing 45 км 75 км System length 9000 км 12700 км

  • Combination 3dB in Rx sensitivity, better nonlinear

tolerance in pulse overlapped regimes, and better FEC

 Very difficult to beat this performance at SE up to 0.4 bit/s/Hz

10G DPSK in Undersea Transmission – Success of Dispersion Management

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The Need for High Spectral Efficiency Will Require Polarization Multiplexed Formats

  • Polarization Multiplexed format shows superior performance

– Higher nonlinear tolerance & higher spectral efficiency – Favors coherent polarization multiplexed transponders

Ref: J.-X. Cai et. al OFC’08, PDP4 50x42.8 Gb/s, 5200 km, 66.7GHz channel spacing 150 km repeater spacing 7 9 11 13 15

  • 6
  • 3

3 6 Pre-Emphasis [dB] Q-Factor [dB] Pol.Mux.- RZ-DBPSK CSRZ-DBPSK RZ-DQPSK

42.8 Gb/s

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Coherent Detection with DSP

  • Ref. A. Salamon, et al., MILCOM 03, M. Taylor, PTL 2004, no. 2, pp. 674–676

PBS 90° Optical Hybrid 90° Optical Hybrid LO A/D DSP A/D A/D A/D Transmission Path

  • Coherent detection allows access to the signal field:

– Polarization de-multiplexing of PDM signals – High spectral efficiency in excess of 1 bit/s/Hz – Digital signal processing at the receiver

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Dispersion Management with Coherent Technology

  • In-line dispersion compensation

can be dropped with coherent Rx

  • No in-line dispersion

compensation reduces nonlinear penalties and improves OSNR

  • Very simple transmission line

design

  • Difficulty: >105 ps/nm need to

be compensated in DSP for the long undersea cases

  • 2
  • 1

1 2 3

  • 2

2 4 6 Relative Launch Power (dB) Delta Q (dB)

Legacy Optimized for coherent

  • 2
  • 1

1 2 3

  • 2

2 4 6 Relative Launch Power (dB) Delta Q (dB)

  • 2
  • 1

1 2 3

  • 2

2 4 6 Relative Launch Power (dB) Delta Q (dB)

Legacy Optimized for coherent

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“Linear” Fibers are Important for Coherent Detection Systems

  • Transition from OOK to PSK with 3 dB better receiver sensitivity

and better FEC resulted in reduction of required power per channel

  • Helped in managing nonlinearity
  • Transition to PDM modulation formats with 40G and 100G rates will

result in higher required OSNR and power per channel

  • We’ll need more “linear”

fibers

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Advanced Fiber Types

) )( ( ) / log( 10 ) (

2 1 2 1

dB SpanLoss SpanLoss A A dB in FOM

eff eff

  

Performance Q(dB) Channel power (dB)

Better nonlinear tolerance

Performance Q(dB)

Channel power (dB)

Better span losses

Performance target Difference in span loss (dB) Smaller loss Higher loss Performance target Aeff1 Aeff2 (Aeff1/A

eff2)[dB]

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Improved Fibers

) )( ( ) / log( 10 ) (

2 1 2 1

dB SpanLoss SpanLoss A A dB in FOM

eff eff

  

180 170 160 150 140 130 120 110 100 90 80 180 170 160 150 140 130 120 110 100 90 80

0.19dB/km, 105m2 0.17dB/km, 150m2 FOM  3.5dB 0.19dB/km, 105m2 0.17dB/km, 150m2 FOM  2.5dB

50 km Spans 100 km Spans

0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.14 0.15 0.16 0.17 0.18 0.19 0.20

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The Push to Higher Spectral Efficiency: New Experimental Results

  • 96x100G over 10600 km (300% spectral efficiency) & 400% spectral

efficiency over 4400 km

  • Short 52 km amplifier spacing (better performance)
  • New experimental transmission

fiber (0.183 dB/km, 150 m2 area)

  • 100G on 33GHz (300%)
  • 100G on 25GHz (400%)
  • Post-deadline paper

– OFC 2010 PDPB10

8 9 10 11 12 5000 10000 15000 Transmission Distance [km] Q-factor [dB] 400% SE 300% SE Transmission distance at optimal power

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Conclusions

  • Advances in fiber technology have played a key role in

the past 20 years of long-haul transmission progress

  • 10G RZ-DPSK in combination with modern dispersion

management have allowed systems with TB/s capacity per fiber pair

  • Next generation systems will need high spectral

efficiency:

– Higher level modulation formats & higher bit rates – Requiring high OSNR/channel – Resulting in very high launch powers

  • Fiber performance is very important for next generation

systems!

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SLIDE 19

2010

Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org

enabling the next generation of networks & services

The 7th International Conference & Convention

  • n Undersea Telecommunications

conference & convention