Peter Winzer

OPTICAL NETWORK SCALING SPATIAL AND SPECTRAL SUPERCHANNELS

Peter J. Winzer Optical Transmission Systems and Networks Research Bell Labs, Alcatel-Lucent, USA COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

ACKNOWLEDGMENT Bell Labs

S.Chandrasekhar A.R.Chraplyvy C.R.Doerr R.-J.Essiambre N.K.Fontaine G.J.Foschini A.H.Gnauck H.Kogelnik G.Kramer X.Liu S.Randel G.Raybon R.Ryf M.Salsi R.W.Tkach C.Xie

Optical Fiber Solutions D.DiGiovanni J.Fini L.Gruner-Nielsen R.V.Jensen X.Jiang R.Lingle A.McCurdy D.Peckham T.F.Taunay S.Yi B.Zhu

Sumitomo Electric T.Hayashi M.Hirano Y.Yamamoto T.Sasaki T.Taru

AND MANY OTHERS COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

Tb/s

100

?

[P. J. Winzer, IEEE Comm. Mag. 26-30 (2010)]

10

?

1 100 Gb/s

Serial Interface Rates and WDM Capacities

OPTICAL NETWORKS SCALING CHALLENGES IN A NUTSHELL

10 1 1986

1990

1994

1998

2002

2006 2010

2014

2018

2022

• Interface rates available up to 200 Gb/s per carrier • How do we get to Terabit channels ? • WDM systems available up to ~20 Tb/s, saturating at ~50 Tb/s • How can we scale to Petabit capacities ? 3 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

SCALING LINE INTERFACE RATES Polarization Physical dimensions Time

Quadrature • 100-Gbaud not widely supported by electronics • Intolerant to CD (~R2) and PMD (~R) • Doesn’t scale WDM spectral efficiency Serial interface rates [Gb/s]

Space

Frequency

CD: Chromatic dispersion PMD: Polarization-mode dispersion

1000 107-Gbaud on/off keying

100 10 1 1986

[Winzer et al., ECOC 2005]

1990

1994

1998

4 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

2002

2006 2010

2014

2018

2022


Quadrature • 100-Gbaud not widely supported by electronics • Intolerant to CD (~R2) and PMD (~R) • Doesn’t scale WDM spectral efficiency  Exploit phase dimension (2x parallelization) Serial interface rates [Gb/s]

Space

Frequency

1000

2x parallel (I/Q)

100 10

56-Gbaud DQPSK

1 1986

[Winzer et al., ECOC 2006]

1990

1994

1998


2002

2006 2010

2014

2018

2022

SCALING LINE INTERFACE RATES Polarization

[C.R.S.Fludger et al., OFC 2007]

Physical dimensions Time

Quadrature Polarization multiplexing lowered symbol rates to ~10 Gbaud (40G) and ~25 Gbaud (100G)  Can use fast (CMOS) A/D converters  Digital coherent (intradyne) detection Serial interface rates [Gb/s]

Space

Frequency

1000

2x parallel (I/Q)

100

2x parallel (pol.)

10 1 1986

1990

1994

1998


2002

2006 2010

2014

2018

2022


Quadrature Current state of research: • 856-Gb/s PDM-16-QAM (107-Gbaud) Serial interface rates [Gb/s]

Space

Frequency

107 Gbaud P M16-QAM

[G. Raybon et al., ECOC (2013)]

1000

107 Gbaud QPSK

100 10 1 1986

1990

1994

1998


2002

2006 2010

2014

2018

2022

DIGITAL COHERENT DETECTION 2x2 MULTIPLE-INPUT MULTIPLE-OUTPUT (MIMO) PBS Signal 1

PBS

Fiber y

Axxx + Axyy

Polarization rotation

Ayxx + Ayyy

Signal 2 x

2 x 2 M I M O DSP engine

• Digital polarization de-rotation • Digital frequency & phase locking • Digital impairment compensation

MIMO DSP: Multiple-input multiple-output digital signal processing 8 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

MODERN OPTICAL TRANSPONDERS LOTS OF DIGITAL PROCESSING t

DAC Client Interfaces

FEC Enc.

Transmit DSP

DAC DAC

PDM I/Q-MOD

F TX Laser

DAC ADC FEC Dec.

Receive DSP

ADC ADC ADC

LO Laser

PDM Coherent Receiver

[Doerr et al., OFC 2009]

Monolithic Silicon Coherent Receiver FEC: Forward error correction PDM: Polarization-division multiplexing DSP: Digital signal processing DAC: Digital-to-analog converter ADC: Analog-to-digital converter 9 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

f

CONSTELLATION SIZE VERSUS SYMBOL RATE

PDM 512-QAM 3 GBaud (27 Gb/s)




PDM QPSK 107 GBaud (224 Gb/s)

[Okamoto et al., ECOC’10]

[Nakazawa et al., OFC’10]

[Gnauck et al., OFC’11]

[Raybon et al., PTL’12]

[Raybon et al., PTL’12]

ADC & DAC resolution

Bandw idth [Winzer, J. Lightwave Technol. 30, 3824 (2012)]

[R. H. Walden, JSAC (1999), and Proc. CSIC (2008)] [A. Khilo et al., Opt. Ex. (2012)]

Line rate [Gb/s]

300

16-QAM

200

100

1

2


3

4 5 6 Bits per symbol

7

8

9

TERABIT INTERFACES AND BEYOND OPTICAL SUPERCHANNELS Polarization Space


200 GHz

Frequency

Quadrature 200 GHz

263 GHz 300 GHz

1 Tb/s (2 subcarriers) 16-QAM 1 Tb/s (4 subcarriers) 16-QAM 1.5 Tb/s (8 subcarriers) 16-QAM 1.2 Tb/s (24 subcarriers) QPSK 5.2 bit/s/Hz 5.0 bit/s/Hz 5.7 bit/s/Hz 3 bit/s/Hz 3200 km transmission 2400 km transmission 5600 km transmission 7200 km transm. [Raybon et al., IPC’12]

[Renaudier et al., OFC’12]

[Liu et al., ECOC’12]

Electronics com plex ity

[Chandrasekhar et al., ECOC’09]

Optics com plex ity 11

COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

TERABIT INTERFACES AND BEYOND OPTICAL SUPERCHANNELS Polarization Space

Frequency


Quadrature

DWDM Superchannel • Cohesive spectral entity • Parallelization requires integration

Laser

Mod.

Laser

Mod.

Laser

Mod.

Laser

Mod.

Electronics com plex ity

f f f f f

Optics com plex ity 12

COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

+

SUPERCHANNEL TRANSPONDER INTEGRATION SPECTRAL SUPERCHANNEL TX DSP TX DSP Client Interface

TX DSP RX DSP RX DSP RX DSP

DAC DAC DAC DAC DAC DAC DAC DAC DAC DAC DAC DAC ADC ADC ADC ADC ADC ADC ADC ADC ADC ADC ADC ADC

PDM IQ-MOD

Laser +

PDM IQ-MOD

Laser

PDM IQ-MOD

Laser

PDM IQ-MOD

Laser

PDM IQ-MOD

Laser

PDM IQ-MOD

Laser

[H. Yamazaki et al., Opt. Ex. 19, B69 (2011)]

10 x 14.25 GBd PDM-QPSK Transmitter

[F. A. Kish et al., JSTQE 17, 1470 (2011)]


Spectrum [dB]

SUBCARRIER ADD/DROP IN SUPERCHANNELS AN OPTO-ELECTRONIC INTERFEROMETER 10 dB

10 dB

10 dB

RS

RS

RS

Frequency

Optical input

Frequency

Frequency

Optical input

Optical output

Optical processing

Optical output

Digital electrical processing

[P. J. Winzer, J. Lightwave Technol. 1775 (2013)] (earlier patents by Taylor, Morita, Winzer) 14 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

Spectrum [dB]

SUBCARRIER ADD/DROP IN SUPERCHANNELS AN OPTO-ELECTRONIC INTERFEROMETER 10 dB

10 dB

10 dB

RS

RS

RS

Frequency

Frequency

Frequency Sout(f)

Sin(f)

Laser

fL≈ fi

si(t)

Drop data output

fi

A

B si(t)

Add data input

[P. J. Winzer, J. Lightwave Technol. 1775 (2013)] (earlier patents by Taylor, Morita, Winzer) 15 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

π/2

Subcarrier modulation

Q

A/D

I

Subcarrier demodulation

Subcarrier extraction

D/A

f

90-deg. hybrid

fi

DSP

si(t)

I Q

fi I/Q modulator

f

f

Tb/s

100

?

[P. J. Winzer, IEEE Comm. Mag. 26-30 (2010)]

10

?

1 100 Gb/s

Serial Interface Rates and WDM Capacities

OPTICAL NETWORKS SCALING CHALLENGES IN A NUTSHELL

10 1 1986

1990

1994

1998

2002

2006 2010

2014

2018

2022

• Interface rates available up to 200 Gb/s per carrier • How do we get to Terabit channels ? • WDM systems available up to ~20 Tb/s, saturating at ~50 Tb/s • How can we scale to Petabit capacities ? 16 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

Spectral efficiency per polarization [b/s/Hz]

THE (LINEAR) SHANNON LIMIT SPECTRAL EFFICIENCY VS. SIGNAL-TO-NOISE RATIO 10 SE = log2 (1 + SNR)

256 64

16

2x 2x

4

1 0

3.7 dB 8.8 dB 5 10 15 20 Required SNR per bit [dB]

25

• For every bit of higher spectral efficiency, ~3 dB more SNR are needed [C. E. Shannon, BLTJ (1948)]

 16-QAM turns out to be a good compromise 17 COPYRIGHT © 2013 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

Spectral efficiency [b/s/Hz]

APPROACHING SHANNON IN OPTICS 4D, CODED MODULATION, SHAPING, MAP DETECTION 10

Constellation shaping

256-QAM 64-QAM

Coded modulation 16-QAM Over-filtering & MAP

4-QAM

[Liu et al., OFC’12] ISI

MAP

[Cai et al., ECOC’10]

1 [P. J. Winzer, JLT, 2012]

0

5 10 15 20 Required SNR per bit [dB]

25 [Karlsson & Agrell, ECOC’10]

ISI: Inter-symbol interference; MAP: Maximum a posteriori


15

10

Commercial WDM needs ca. 2016 … 2018