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IEEE Talk(April 24, 2015)
Generation, Detection, and Transmissionof Terabit/s and Higher “Channel” Rates
Using Multicarrier Solutionsg
S. ChandrasekharB ll L b t i Al t l L tBell Laboratories, Alcatel-Lucent
Holmdel, New Jersey, USA
All Rights Reserved, Alcatel-Lucent1S. Chandrasekhar, IEEE Talk, April 2015
AcknowledgementsI would like to thank many colleagues at Bell Labs for collaboration and discussionI would like to thank many colleagues at Bell Labs for collaboration and discussion. Among them are:
Xiang Liu (now at Futurewei)P. J. WinzerS. RandelG. RaybonA AdamieckiA. AdamieckiN. FontaineR. RyfD. NeilsonP DP. DongA. R. ChraplyvyR. W. Tkach
All Rights Reserved, Alcatel-Lucent2S. Chandrasekhar, IEEE Talk, April 2015
Outline
Modern Optical Transmission Systems
Superchannel ConceptSuperchannel Concept
Implementation
S ft D fi d T i iSoftware-Defined Transmission
Enabling Technologies
Flexible-Grid WDM
Novel Superchannel Techniques
Conclusion
All Rights Reserved, Alcatel-Lucent3S. Chandrasekhar, IEEE Talk, April 2015
Modern Optical TransmissionModern Optical TransmissionModern Optical Transmission Modern Optical Transmission SystemsSystems
All Rights Reserved, Alcatel-Lucent4S. Chandrasekhar, IEEE Talk, April 2015
Optical networks: backbone of the internet
Line interface
Reconfigurable opticaladd/drop multiplexer(ROADM)
Client interface(e.g., 4 x 25 Gbit/s)
(e.g., 100 Gbit/s)Router
Optical network
WDM system( 80 100 Gbit/ ) S t l ffi i (SE) i [b/ /H ]
Tx Rx
~ 5 THz bandwidth ~ 100 km of fiber
(e.g., 80 x 100 Gbit/s)
• Increase per-wavelength interface rate• Increase aggregate per fiber capacity
Spectral efficiency (SE) in [b/s/Hz]: SE = per-channel bit rate / WDM spacing
All Rights Reserved, Alcatel-Lucent5S. Chandrasekhar, IEEE Talk, April 2015
• Increase aggregate per-fiber capacity• Increase network flexibility
Evolution of optical transport networks1980 1990 2000 2010 2020
2.5 Gb/s 10 Gb/s 40 Gb/s 100 Gb/s Single-span
Channel rate:System type: Multi-span (EDFAs) Optically routed networks SDON?
1 Tb/s
10
100
paci
ties
s
1
10
d W
DM
Cap
Tb/s
2.5 dB/yr
100
ce R
ates
an (78%/yr)
[P. J. Winzer,
10
Seria
l Int
erfa
Gb/
s
1IEEE
IEEEITU-T
IEEEITU-T
[ ,IEEE Com. Mag., July 2010 ]
All Rights Reserved, Alcatel-Lucent6S. Chandrasekhar, IEEE Talk, April 2015
1986 1990 1994 1998 2002 2006
S
2010 2014 20181
2022
Dimensions for modulation and multiplexing[P. J. Winzer, S. Chandrasekhar and X. Liu, “Modulation Formats and Receiver Concepts for Optical Transmission Systems,”OFC’14 Short Course SC105]OFC 14, Short Course SC105]
http://www.occfiber.com/
SpaceSpacePolarization
Wavelength or FrequencySpaceSpace Wavelength or Frequency
Time Quadrature
Physical dimensions
Current R&D explores all these dimensionsCurrent R&D explores all these dimensions
All Rights Reserved, Alcatel-Lucent7S. Chandrasekhar, IEEE Talk, April 2015
Current R&D explores all these dimensionsCurrent R&D explores all these dimensions
Modulation format choices
Quadrature
M ltil lIntensity Phase
Memoryless
ASK/PSKQAM
Multilevel
Memoryless With memoryBinary MultilevelCorrelative codingBinary Pseudo-MultilevelMultilevel
OOK
C-NRZDST
CRZACRZ
M-ASK CSRZVSB-CSRZAP formats DB
PSBTPASSCAPSAMI
(DCS)
(D)PSK (D)QPSK
Chirp-free ChirpedPartial response
NRZ RZ NRZ RZNRZ RZ NRZ RZ
VSBSSB
DST ACRZ
Im{E}
I/Q modulationI/Q modulation
E : Optical field
Re{E}
All Rights Reserved, Alcatel-Lucent8S. Chandrasekhar, IEEE Talk, April 2015
E : Optical field
“Si l i i t it b t h it f ll bi th i bilit f“Si l i i t it b t h it f ll bi th i bilit f
DSP – Innovatively tailored for optical transport
“Signal processing is at its best when it successfully combines the unique ability of mathematics to generalize with both the insight and prior information gained from
the underlying physics of the problem at hand” [S. Haykin, “Signal processing: Where physics and mathematics meet,” IEEE Signal Process. Mag, 2001]
“Signal processing is at its best when it successfully combines the unique ability of mathematics to generalize with both the insight and prior information gained from
the underlying physics of the problem at hand” [S. Haykin, “Signal processing: Where physics and mathematics meet,” IEEE Signal Process. Mag, 2001]
uenc
ym
atio
n
cisi
on
ADC1
dem
ux
hase
mat
ion
com
p.
ecov
ery
Freq
Est
i m
DecADC2
and
Pol
-d Ph
Est
im
CD
c
Clo
ck R
eADC3
ADC4 D c
omp.
a
com
p.
quen
cym
atio
n
cisi
on
hase
mat
ion
CADC4
PM
D
CD
Freq
Est
im
DecPh
Est
imAll Rights Reserved, Alcatel-Lucent9S. Chandrasekhar, IEEE Talk, April 2015
12 TeraOperations/sec (TOPs) for 40Gb/s, and ~30 TOPs for 100Gb/s (~7,000 PCs)
Moore’s Law is still marching on! Dr. Kevin Kahn, Intel Senior Fellow
All Rights Reserved, Alcatel-Lucent10S. Chandrasekhar, IEEE Talk, April 2015
22 Superchannel ConceptSuperchannel Concept22 Superchannel ConceptSuperchannel Concept
All Rights Reserved, Alcatel-Lucent11S. Chandrasekhar, IEEE Talk, April 2015
In the context of optical transport networks the term “superchannel” was
The term “Superchannel”In the context of optical transport networks, the term superchannel wasfirst used in 2009* to refer to multiple single-carrier-modulated signals that areseamlessly multiplexed under the coherent optical orthogonal frequency-division multiplexing (CO-OFDM) conditions.
*: [S. Chandrasekhar, X. Liu, B. Zhu, and D. W. Peckham, “Transmission of a 1.2-Tb/s 24-carrier no-guard-intervalcoherent OFDM superchannel over 7200-km of ultra-large-area fiber,” ECOC’09, PD2.6]
The superchannel concept was later generalized to any collection of opticalsignals that are
modulated and multiplexed together with high SE at a commonoriginating site,transmitted and routed together over a common optical link andtransmitted and routed together over a common optical link, andreceived at a common destination site.
For signals that are not seamlessly bundled together, i.e., there is a spectralb t i l th t “ h l” i l ft dgap between signals, the term “super-channel” is also often used.
Much work has been done since then. ITU has recently standardized the useof superchannels in “flexible grid WDM” [ITU-T G.694.1]
All Rights Reserved, Alcatel-Lucent12S. Chandrasekhar, IEEE Talk, April 2015
p g [ ]
IEEE Xplore search on “Superchannel”Search by “superchannel”Search by “superchannel” Search by “super channel”Search by “super channel”Search by superchannelSearch by superchannel Search by super-channelSearch by super-channel
First record in 2009.215 Google citations as of 4/21/2015
First record in 2009.215 Google citations as of 4/21/20154/21/2015.4/21/2015.
All Rights Reserved, Alcatel-Lucent13S. Chandrasekhar, IEEE Talk, April 2015
Benefits of superchannel
Higher “per-channel” data rate Avoiding electronic bottlenecks and easing wavelength management
Higher spectral efficiency (SE)Due to better spectrum utilization, especially with flexible-grid WDM
Better leveraging large-scale integration of photonic integrated circuits (PICs) and application specific integrated circuits (ASICs)
Increased efficiency in digital signal processing (DSP)
Supporting software-defined optical transmission and potentially future software-defined optical network (SDON)
As transmitter DSP (required for spectral shaping) is already in place
All Rights Reserved, Alcatel-Lucent14S. Chandrasekhar, IEEE Talk, April 2015
Channel (or carrier) Spacing = Δf; Symbol Rate = B
Conventional WDM classifications Channel (or carrier) Spacing = Δf; Symbol Rate = B
Δf/B >5.0: legacy WDM and coarse WDM10G over 100-GHz
1.2 < Δf/B ≤ 5.0: common Dense WDM (DWDM)10Gbaud/28Gbaud over 50-GHz; 40Gbaud over 100-GHz;14.3Gbaud over 25-GHz.
1.0 < Δf/B ≤ 1.2: “Quasi-Nyquist-WDM” and “Guard-banded-OFDM”32Gbaud PDM-QPSK on 37.5GHz
Δf/B = 1.0: “Nyquist-WDM”Δf/B 1.0: Nyquist WDM28Gbaud PDM-QPSK on 28GHzCoherent WDM and NGI-CO-OFDM are special cases of Nyquist-WDM thatadditionally satisfy the OFDM conditions
Δf/B <1.0: “Super-Nyquist-WDM” (or “Faster-than-Nyquist”)30Gbaud PDM-QPSK on 25GHz
The last three WDM classes are commonly supported by superchannels
All Rights Reserved, Alcatel-Lucent15S. Chandrasekhar, IEEE Talk, April 2015
The last three WDM classes are commonly supported by superchannels
Electrical OFDM
OFDM: where modulation and multiplexing mergeOFDM: where modulation and multiplexing merge
f
56 Gb/s net rate (65 Gb/s line rate)32-QAM per subcarrier[Takahashi et al., OFC’09]All subcarriers modulated at oncef
f
Mod.Laser
Optical OFDMMod.
ff M d
f
All subcarriers modulated individuallyParallel optical hardware
Comb
f
f
f
f
Mod.
Mod.
Mod.
60 GHz
65 GHz300 GHz
448 Gb/s (10 subcarrier) 16-QAM5 bit/s/Hz 2000-km transmission
[X Li t l OFC’10]
606 Gb/s (10 subcarrier) 32-QAM7 bit/s/Hz 1600-km transmission
[X Li t l ECOC’10]
1.2 Tb/s (24 subcarrier) QPSK3.74 bit/s/Hz 7200-km transmission[S Ch d kh t l ECOC’09]
All Rights Reserved, Alcatel-Lucent16S. Chandrasekhar, IEEE Talk, April 2015
[X. Liu et al., OFC’10] [X. Liu et al., ECOC’10][S. Chandrasekhar et al., ECOC’09]
[S. Chandrasekhar and X. Liu, Opt. Ex., p.21350, 2009]
The OFDM condition
Frequency-locked carriersPhase locking is not a necessary conditionPhase locking is not a necessary condition
Carrier Spacing = Symbol Rate
Symbols in the carriers time-alignedSynchronous at de-multiplexing
S ffi i t t itt b d idthSufficient transmitter bandwidth
Sufficient sampling speedOversampling along with appropriate anti-aliasing filters in the DSPOversampling along with appropriate anti aliasing filters in the DSP
See also:“Coherent WDM” [A Ellis et al PTL p 504 2005]
All Rights Reserved, Alcatel-Lucent17S. Chandrasekhar, IEEE Talk, April 2015
Coherent WDM [A. Ellis et al., PTL, p.504, 2005]“2-Carrier NGI-CO-OFDM“ [E. Yamada et al., OFC’08, PDP8, 2008]
Multiplexing with a guard band (GB)[S. Chandrasekhar and X. Liu, “Advances in Tb/s Superchannels”, Optical Fiber Telecommunications VI, Edited by Ivan P Kaminov Tingye Li and Alan Willner Academic Press 2013]
⎟⎞
⎜⎛ ⋅⎟
⎞⎜⎛
∑∑∞∞
22 FFTNGBGB
To avoid the stringent OFDM condition, signals can be multiplexed with a GB. The amount of the worst-case crosstalk imposed on the edge subcarriers can be expressed as
Edited by Ivan P. Kaminov, Tingye Li, and Alan Willner, Academic Press, 2013]
⎟⎟⎠
⎞⎜⎜⎝
⎛+=⎟⎟
⎠
⎞⎜⎜⎝
⎛+
Δ= ∑∑
=
−
=
−
0
2
0
2 )]([log10)]([log10)(n OFDM
FFT
n SC
nB
NGBn
fGBdBX ππ
where ΔfSC, NFFT, and BOFDM are the OFDM subcarrier spacing, FFT/IFFT size used in OFDM, and the spectral bandwidth of the OFDM signal, respectively.
-16
-14
-12
-10
ubca
rrier
s (d
B)
NFFT=128
NFFT=256
567
dB]
QPSK 16-QAM 64-QAM
[P. J. Winzer, Proc. ECOC (2011)]
24
-22
-20
-18
alk
on th
e ed
ge s
u
1234
NR
pen
alty
[d
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2-28
-26
-24
GB/BOFDM
Cro
ssta
10 15 20 25 30 35 40 45
01
5Crosstalk [dB]
OS
All Rights Reserved, Alcatel-Lucent18S. Chandrasekhar, IEEE Talk, April 2015
A GB-to-Baud ratio of ~0.1 gives a good tradeoff between SE and simplicity
ImplementationImplementationImplementationImplementationGenerationGeneration
All Rights Reserved, Alcatel-Lucent19S. Chandrasekhar, IEEE Talk, April 2015
( ) OFDM b d ltib d (b) N i t WDM i ( ) N i t WDM i
Generation methods
OF
OF
(a) OFDM-based multiband transmitter
(b) Nyquist-WDM usingoptical filtering
(c) Nyquist-WDM usingdigital filtering
SB-TX
Multicarrier SB-TX
bine
r
DMUX SB-TX
SB-TX
bine
rLaser
Laser
SB-TX with DF
SB-TX with DF
bine
rLaser
Laser
OF
…Multicarriergenerator
SB-TX
…
Com
bSB-TX
…
Com
b
Laser
…
SB-TX with DF
…
Com
b
Laser
…(frequency-
locked carriers)
DMUX: wavelength de-multiplexer; SB-TX: single-band transmitter; OF: optical filter; DF: digital filter.
MultibandTX type
Frequency locking?
OF needed?(band spacing)
SB-TXtype used*
TX-BW ADCspeedyp g ( p g) yp p
(a) OFDM-based
Yes No(B)
SB-(a), SB-(b) >~2B* >~4B*SB-(c) ~B ~1.5B
(b) Nyquist-WDM w/ OF
No Yes (~1.1B*)
SB-(a), SB-(b) ~B ~2B( )
(c) Nyquist-WDM w/ DF
No No(~1.1B*)
SB-(b), SB-(c) ~B 1.5B~2B
* SB-(a): Single-carrier PDM-QAM w/o DAC; SB-(b): Single-carrier PDM-QAM w/ DAC;SB-(c): CO-OFDM with PDM-QAM subcarriers
All Rights Reserved, Alcatel-Lucent20S. Chandrasekhar, IEEE Talk, April 2015
SB (c): CO OFDM with PDM QAM subcarriers.
OFDM-based seamless multiplexing[S. Chandrasekhar and X. Liu et al., ECOC’09, PD2.6] [X. Liu and S. Chandrasekhar et al, OFC 2011]
1.12-Tb/s 24-carriersNGI-CO-OFDM PDM-QPSK
0
485-Gb/s 10-carrier RGI-CO-OFDM PDM-16QAM
-20
-10
(dBm
)
-40
-30
1.2-Tb/s Superchannel
PO
WE
R (
-501554 1555 1556 1557
1.2 Tb/s Superchannel24 Frequency-locked Carriers
WAVELENGTH (nm)( )
12.5-GHz spaced carriers12.5-Gbaud PDM-QPSK per carrier
Intra-channel SE = 3.74 b/s/Hz7200 km over ULAF
6.5-GHz spaced carriers/bands48.5-Gb/s PDM-16QAM per carrier
Intra-channel SE = 7.0 b/s/Hz4800 km over ULAF
All Rights Reserved, Alcatel-Lucent21S. Chandrasekhar, IEEE Talk, April 2015
7200-km over ULAF 4800-km over ULAF
Guard-banded multiplexing[X. Liu and S. Chandrasekhar et al., ECOC’12, post-deadline paper Th.3.C.5]
λ1λ3λ5λ7
EDFA EDFA
Cou
pler
ler
PDM I/Q modulator
I Q QIEDFA
Modulation: (1) Reduced-guard-interval (RGI)
xI
λ2λ4λ6λ8
EDFA EDFA
Cou
pler C
oupl
xQ yI yQ
xI xQ yQyI
PDM I/Q modulator
Delay CO-OFDM with PDM-16QAM(2) Single-carrier PDM-16QAM with
Nyquist filteringSymbol rate: ~32 Gbaud.
DAC DAC DAC DACTransmitter-side
offline DSP
50~64 GSa/s Guard band to baud ratio: ~10%.
1.6-Gb/s quasi-Nyqusit-WDM superchannel
-10
0
wer
(dB
)-10
-5
0
wer
(dB)
Even signalsOdd signalsEntire superchannel
1.5-Gb/s RGI-CO-OFDM superchannel
-30
-20
Rel
ativ
e po
w
OSA resolution: 4 GHz
35
-30
-25
-20
-15
Rel
ativ
e P
ow
OSA resolution: 0.02 nm
All Rights Reserved, Alcatel-Lucent22S. Chandrasekhar, IEEE Talk, April 2015
-150 -75 0 75 150Frequency offset (GHz)
1549.5 1550 1550.5 1551 1551.5 1552-35
Wavelength (nm)
[G. Raybon et al, Proc. IEEE Photonics Conference, Sept. 2012, post-deadline paper PD1.2.]
1-Tb/s 2-carrier quasi-Nyquist-WDM superchannel
80-Gb/s Quadrature
(Q)
Delay
PRBS Gen40 Gb/s
2:1Mux
DFB 50 GHZ
Channel
200 ps
80 Gb/s
π/2EDFA
ECL
DFB
DFB
DFB
DFB
OF
50 G
Sub-carrier 280-Gb/s In-phase (I)
215-1
PRBS Gen40 Gb/s
2:1Mux
3 dBDFB 50 GHZ
-20
-10
0
Wavelength, nm1548 1557
Sub-carrier 1Sub ca e
-50
-40
-30
f0 f2f1Very high speed electronics at transmitter; 160-GSa/s 66-GHz ADC at receiverOptical equalizer to shape modulation format and overcome bandwidth limitationHighest achieved single carrier bit-rate is 640Gb/s, 80 Gbaud PDM-16QAM
Very high speed electronics at transmitter; 160-GSa/s 66-GHz ADC at receiverOptical equalizer to shape modulation format and overcome bandwidth limitationHighest achieved single carrier bit-rate is 640Gb/s, 80 Gbaud PDM-16QAM
All Rights Reserved, Alcatel-Lucent23S. Chandrasekhar, IEEE Talk, April 2015
Successful transmission over 3200-km with a SE of 5.0-b/s/Hz Successful transmission over 3200-km with a SE of 5.0-b/s/Hz
Super-Nyquist-WDM -1Super-Nyquist-WDM (SNW): Modulation symbol rate < channel spacingSuper-Nyquist-WDM (SNW): Modulation symbol rate < channel spacing
[J. -X. Cai et al., OFC2009, PDPB10 (2009)]
Typically, SNW offers higher SE at the expense of (i) additional OSNR penalty and (ii) increased DSP complexity for removing the ISI caused by SNW.With PDM QPSK and modest SNW low complexity SNW receiver may be realized:With PDM-QPSK and modest SNW, low-complexity SNW receiver may be realized: an interesting approach when a slight SE increase is desired.
[J. Li, M. Sjödin, M. Karlsson, and P. A. Andrekson, Opt. Express 20, 10271-10282 (2012) ]
11 carriers spaced at 25-GHz28-Gbaud PDM-QPSK (112G per carrier)
TX-side: optical pre-filtering RX-side: duobinary-shaping & MLSD
All Rights Reserved, Alcatel-Lucent24S. Chandrasekhar, IEEE Talk, April 2015
( p )Intra-channel SE ~ 4.19 b/s/Hz
y p gAdditional OSNR penalty: ~1.8 dB @BER=10-3
Super-Nyquist-WDM -2140 7 Tbit/s 7 326 km transmission of 7x201 channel 25 GHz spaced140 7 Tbit/s 7 326 km transmission of 7x201 channel 25 GHz spaced140.7-Tbit/s, 7,326-km transmission of 7x201-channel 25-GHz-spaced Super-Nyquist-WDM 100-Gbit/s optical signals using a 7-core fiber, achieving a record capacity-distance product of 1.03 Exabit/s⋅km,
was recently demonstrated [K. Igarashi et al., ECOC’13, post-deadline paper PD3.E.3.]
140.7-Tbit/s, 7,326-km transmission of 7x201-channel 25-GHz-spaced Super-Nyquist-WDM 100-Gbit/s optical signals using a 7-core fiber, achieving a record capacity-distance product of 1.03 Exabit/s⋅km,
was recently demonstrated [K. Igarashi et al., ECOC’13, post-deadline paper PD3.E.3.]
(a): Concept of Super-Nyquist-WDM transmission (30Gbaud over 25-GHz: SE=4 b/s/Hz after removing 20% overhead for SD-FEC); (b): Impulse response; (c): Power spectrum of
All Rights Reserved, Alcatel-Lucent25S. Chandrasekhar, IEEE Talk, April 2015
duobinary-pulse shaping; (d): Duobinary trellis for two-level amplitude modulation.
ImplementationImplementationImplementationImplementationDetectionDetection
All Rights Reserved, Alcatel-Lucent26S. Chandrasekhar, IEEE Talk, April 2015
Banded detection of superchannelsOptical Filter-free detection (In ROADM jargon- Colorless Drop)
Example: N-band superchannel and M detection bands (M<N)
Optical Filter free detection (In ROADM jargon Colorless Drop)Receiver hardware complexity reduced by detection of more than 1 band
Each detected band uncorrelated
Dispersion compensation t OFDM ditimust ensure OFDM conditions
satisfied among carriers ofeach band
All Rights Reserved, Alcatel-Lucent27S. Chandrasekhar, IEEE Talk, April 2015
Oversampling Ratio for multiband detectionBanded detection: X. Liu et al., Proc. OFC’10, OWO2
Oversampling ratio (OSR) sampling rate/net detected baudOversampling ratio (OSR) = sampling rate/net-detected-baud
fOLO=f0
Δf li =4xB Δfsampling=4xB
fOLO=(f0+f1)/2 fOLO=f0
Δfsampling=4xBΔfsampling 4xB
f0 f1=f0+B f0 f1f-1 f2 f0 f1f-1f-2 f2
OSR=4 OSR=2 OSR=1.33
All Rights Reserved, Alcatel-Lucent28S. Chandrasekhar, IEEE Talk, April 2015
485-Gb/s PDM-16QAM with 10 bands detected with 80-GSa/sOSR = (80/485)*8 = 1.31
728-Gb/s PDM-64QAM with 10 bands detected with 80-GSa/sOSR = (80/728)*12 = 1.32
Various superchannel demonstrations
263 GHz300 GHz
200 GHz 200 GHz
1 Tb/s (2 subcarriers) 16-QAM5 2 bit/s/Hz
1.5 Tb/s (8 subcarriers) 16-QAM5 7 bit/s/Hz
1.2 Tb/s (24 subcarriers) QPSK3 74 bit/s/Hz
1 Tb/s (4 subcarriers) 16-QAM5 0 bit/s/Hz5.2 bit/s/Hz
3200 km transmission[Raybon et al., IPC’12]
5.7 bit/s/Hz5600 km transmission
[Liu et al., ECOC’12]
3.74 bit/s/Hz7200 km transmission
[Chandrasekhar et al., ECOC’09]
ADC&DAC b d idth & l tiADC&DAC b d idth & l ti O ti l ll liO ti l ll li
5.0 bit/s/Hz2400 km transmission
[Renaudier et al., OFC’12]
ADC&DAC bandwidth & resolutionADC&DAC bandwidth & resolution Optical parallelismOptical parallelism
Few carriersHigh symbol rate
Large # of carriersLower symbol rate
The optimal choice depends on implementation platforms and applicationsThe optimal choice depends on implementation platforms and applications
g y y
All Rights Reserved, Alcatel-Lucent29S. Chandrasekhar, IEEE Talk, April 2015
Modulation Format Superchannel Composition ISE* Reach ISEDP
Recent Tb/s-class superchannel demonstrationsModulation Format Superchannel
data rateComposition ISE
(b/s/Hz)Reach(km)
ISEDP(km⋅b/s/Hz)
Seamless CO-OFDM (with frequency-locked optical carriers)
PDM-QPSK 1200 Gb/s 24× 50Gb/s 3.74 7200 26928
PDM-16QAM 1500 Gb/s 15× 100Gb/s 7.00 1200 8400
RGI OFDM 16QAM 485 Gb/ 10 48 5Gb/ 6 20 4800 29760RGI-OFDM-16QAM 485 Gb/s 10× 48.5Gb/s 6.20 4800 29760
Guard-banded CO-OFDM (with frequency-unlocked carriers)
OFDM-16QAM 1864 Gb/s 8× 233Gb/s 5.75 5600 32000
Quasi-Nyquist-WDM (with frequency-unlocked carriers)
PDM-64QAM 538 Gb/s 8× 67Gb/s 8.96 1200 10752
PDM-16QAM 1280 Gb/s 2× 640Gb/s 5.00 3200 16000
Super-Nyquist-WDM (with frequency-locked carriers)
PDM QPSK 1232 Gb/s 11× 112Gb/s 4 19 >640 >2560
All Rights Reserved, Alcatel-Lucent30S. Chandrasekhar, IEEE Talk, April 2015
PDM-QPSK 1232 Gb/s 11× 112Gb/s 4.19 >640 >2560*ISE: intra-channel spectral efficiency (net channel data rate over channel bandwidth)
44 SoftwareSoftware--defineddefined44 SoftwareSoftware defined defined transmissiontransmission
All Rights Reserved, Alcatel-Lucent31S. Chandrasekhar, IEEE Talk, April 2015
Adaptive modulation for Tb/s-class superchannels[S. Chandrasekhar and X. Liu, “Advances in Tb/s Superchannels”, Optical Fiber Telecommunications VI, Edited by Ivan P Kaminov Tingye Li and Alan Willner Academic Press 2013]
PDM-16-QAM PDM-32-QAM PDM-64-QAM PDM-256-IPM
Edited by Ivan P. Kaminov, Tingye Li, and Alan Willner, Academic Press, 2013]
PDM-16-QAM PDM-32-QAM PDM-64-QAM PDM-256-IPM(8 bits/symbol) (10 bits/symbol) (12 bits/symbol) ( 16 bits/symbol)
The transmitter DSP and DAC, required to perform spectral shaping for superchannel formation, naturally allows for adaptive modulation for
varying data rates (depending on demand/reach)
All Rights Reserved, Alcatel-Lucent32S. Chandrasekhar, IEEE Talk, April 2015
Adaptive modulation with fine granularityCorrelated information between I and Q phases Time domain interleaving of formats
Adaptive 4-D modulationAdaptive 4-D modulation Adaptive hybrid-QAMAdaptive hybrid-QAM
Correlated information between I- and Q-phases Time-domain interleaving of formats
[X. Zhou, L. E. Nelson, and P. Magill, “Rate-Adaptable Optics for Next Generation Long-Haul Transport Networks ”
[J. K. Fischer, S. Alreesh, R. Elschner, F. Frey, M. Nölle, and C Schubert “Bandwidth-Variable Transceivers Based Optics for Next Generation Long Haul Transport Networks,
IEEE Commun. Mag. 51, 41-49, March 2013] and C. Schubert, Bandwidth Variable Transceivers Based on 4D Modulation Formats for Future Flexible Networks,” ECOC’13, invited paper Tu.3.C.1]
QPSK QPSK16-QAMSymbol duration
All Rights Reserved, Alcatel-Lucent33S. Chandrasekhar, IEEE Talk, April 2015
Also see: [D. Coelho and N.Hanik, ECOC’11, Mo.2.B.4 (2011)]; [M. Sjödin,et al., Opt. Express 20, 8356-(2012)]; [J. Renaudier et al., OFC’13, OTu3B.1].
[G. Bosco, V. Curri, A. Carena, P. Poggiolini, and F. Forghieri, “On the performance of Nyquist-WDM terabit superchannels based on PM BPSK PM QPSK PM 8QAM or PM 16QAM subcarriers ” JLT 29 53 61 (2011)]
Tradeoff between capacity and reachon PM-BPSK, PM-QPSK, PM-8QAM or PM-16QAM subcarriers, JLT 29, 53–61 (2011)]
Maximum reach with BER≤4⋅10-3 versus capacity in the C-band (bottom axis) and spectral efficiency (top axis) for Nyqusit-WDM superchannel with 27 75-Gbaud PM-BPSK (crosses) PM-QPSK (diamonds) PM-
All Rights Reserved, Alcatel-Lucent34S. Chandrasekhar, IEEE Talk, April 2015
axis) for Nyqusit-WDM superchannel with 27.75-Gbaud PM-BPSK (crosses), PM-QPSK (diamonds), PM-8QAM (squares) and PM-16QAM (circles). Solid lines refer to SSMF and dashed lines refer to NZDSF.
Joint optimization of modulation and FEC coding[J Renaudier et al., “1-Tb/s Transceiver Spanning Over Just Three 50-GHz Frequency Slots for Long-Haul Systems ,” ECOC’13 t d dli PD2 D 5]ECOC’13, post-deadline paper PD2.D.5]
FIXED SYMBOL RATE
Superchannel total data rate fixed. Number of carriers fixed. Therefore spectral extent is fixed.Vary constellation size for same symbol rate. Use extra symbol rate for FEC overheadFEC threshold changes, therefore reach changes.
Demonstrated a 1Tb/s transceiver, occupying only three 50-GHz slots and leveraging a joint optimization procedure of modulation format and error correction codingDemonstrated a 1Tb/s transceiver, occupying only three 50-GHz slots and leveraging a joint optimization procedure of modulation format and error correction coding
All Rights Reserved, Alcatel-Lucent35S. Chandrasekhar, IEEE Talk, April 2015
a jo t opt at o p ocedu e o odu at o o at a d e o co ect o cod gIt enabled 51-Tb/s transmission over 2000 km, at 6.7-bit/s/Hz spectral efficiency a jo t opt at o p ocedu e o odu at o o at a d e o co ect o cod gIt enabled 51-Tb/s transmission over 2000 km, at 6.7-bit/s/Hz spectral efficiency
Alternative superchannel formation – fixed information rate[Q. Zhuge, M. Morsy-Osman, M. Chagnon, X. Xu, M. Qiu, and D. V. Plant, “Demonstration of energy efficient and format-
transparent digital signal processing for Tb/s flexible transceiver ” in Proc ACP'13 post deadline paper AF2E 7 (2013)]transparent digital signal processing for Tb/s flexible transceiver,” in Proc. ACP'13, post-deadline paper AF2E.7 (2013)]
10 carriers100 Gb/s (net) per carrier1 Tb/s (net) per superchannel
10 carriers100 Gb/s (net) per carrier1 Tb/s (net) per superchannel1 Tb/s (net) per superchannelVarying baud with format:
PDM-QPSK: 30 GbaudPDM-8QAM: 20 GbaudPDM-16QAM: 15 Gbaud
1 Tb/s (net) per superchannelVarying baud with format:
PDM-QPSK: 30 GbaudPDM-8QAM: 20 GbaudPDM-16QAM: 15 GbaudPDM 16QAM: 15 GbaudPDM 16QAM: 15 Gbaud
Formationmethods
Total data rate *
Spectralefficiency*
TX/RX cost/bit*
Reach Client interface
(1) Fixed log2(M/4) log2(M/4) 1/log2(M/4) Lower as M **
Load baud increases** changes
(2) Fixed data rate
1 log2(M/4) 1 Slightly betterthan (1)
Load unchanged
* Normalized to the case of PDM-QPSK. M is the number of the constellation points of M-QAM.
All Rights Reserved, Alcatel-Lucent36S. Chandrasekhar, IEEE Talk, April 2015
Q p Q**: Larger M can be combined with higher overhead FEC to achieve longer reach for a given SE.
[J Renaudier et al., ECOC’13, post-deadline paper PD2.D.5]
5555 Enabling TechnologiesEnabling Technologies
All Rights Reserved, Alcatel-Lucent37S. Chandrasekhar, IEEE Talk, April 2015
DSP gate counts
Major DSP ASIC milestonesg
100
1000
llion
s)
NEL 2nd gen
Ciena WaveLogic 3
7
8
9
bit
ADC resolution vs. sample rate
ALU 56GS/s
10
100
TE C
OU
NT
(Mi
~70% per year
4
5
6
Num
ber o
f
StatedENOB
12004 2006 2008 2010 2012 2014
GA
T
2
3
0 10 20 30 40 50 60Sample rate [GS/s]
ENOB
70M+ gates70M gates
All Rights Reserved, Alcatel-Lucent38S. Chandrasekhar, IEEE Talk, April 2015
Nortel electronic pre-EDC 10G Tx (2005)20GS/s DAC
Nortel 40Gb/s PDM-QPSK (2007)20GS/s ADC/DSP
Alcatel-Lucent 112Gb/s (2010)56GS/s ADC/DSP
200-Gb/s transponder - pulse shaping, equalization, soft decoding[http://www3.alcatel-lucent.com/400g-pse/ ; http://www.convergedigest.com/2012/09/alcatel-lucent-cites-deployment-of-400g.html; http://www nationmultimedia com/technology/Alcatel Lucent tackles the capacity crunch caused 30177739 html]
DACDAC
TX
200 PDMFEC
http://www.nationmultimedia.com/technology/Alcatel-Lucent-tackles-the-capacity-crunch-caused--30177739.html]
ADC
DACDACDSP
0G C
lient Inte
I/Q-MODTX Laser
PDM LO Laser
Enc.
ADCADC
ADCRXDSP
erfaces
PDMCoherentReceiver
LO LaserFECDec.
Alcatel-Lucent’s 400G Photonic Service Engine
0
-10
ower
(dB
)
Digitally pre-filtered for supporting a SE
gIndustry’s first 400G coherent optical chip Frequency (GHz)
-20Po
-20 0 20
All Rights Reserved, Alcatel-Lucent39S. Chandrasekhar, IEEE Talk, April 2015
of up to 5.3 b/s/Hz (400G over 75 GHz)
400G dual-carrier ASIC and optics[http://www3.alcatel-lucent.com/400g-pse/ ; http://www.convergedigest.com/2012/09/alcatel-lucent-cites-deployment-of-400g.html; http://www nationmultimedia com/technology/Alcatel Lucent tackles the capacity crunch caused 30177739 html]
DACDAC20 Dual-carrier optics integration
http://www.nationmultimedia.com/technology/Alcatel-Lucent-tackles-the-capacity-crunch-caused--30177739.html]
ADC
DACDACDACTX
DSP
00GD
ata Inp
PDMI/Q-MOD
TX Laser
FECEnc. • Dual-PDM Coherent RX
• Dual PDM I/Q-Mod
with Alcatel-Lucent’s 400G
ADCADC
ADCADC
RXDSP
ut/Output
PDMCoherentReceiver
LO LaserFECDec.
with Alcatel Lucent s 400G
coherent ASIC
DACDACDAC
TXDSP
200GD
a
FECEnc.
PDMI/Q-MOD
TX Laser
ADCADCADC
DAC
RXDSP
ata Input/Outp
FECDec.
TX Laser
PDMCoherentR i
LO Laser
All Rights Reserved, Alcatel-Lucent40S. Chandrasekhar, IEEE Talk, April 2015
ADCADC
put Receiver
500-Gb/s photonic integrated circuits (PIC)[J. Rahn et al., OFC/NFOEC’12, post-deadline paper PDP5D.5 (by Infinera)]
The PIC-based transmitter (TX) has 10 integrated lasers, 40 modulatorsrunning at 14.3 GBaud, and an optical Array Waveguide Grating (AWG).The PIC-based transmitter (TX) has 10 integrated lasers, 40 modulatorsrunning at 14.3 GBaud, and an optical Array Waveguide Grating (AWG).The PIC-based receiver (RX) integrates the AWG, per-carrier DFBs,optical hybrids, and photodiodes.Modes of operation
500Gb/s: 10x 25-GHz-spaced 14.3-Gbaud PDM-QPSK, SE=2 b/s/Hz
The PIC-based receiver (RX) integrates the AWG, per-carrier DFBs,optical hybrids, and photodiodes.Modes of operation
500Gb/s: 10x 25-GHz-spaced 14.3-Gbaud PDM-QPSK, SE=2 b/s/Hz
All Rights Reserved, Alcatel-Lucent41S. Chandrasekhar, IEEE Talk, April 2015
250Gb/s: 10x 25-GHz-spaced 14.3-Gbaud TCM-PDM-QPSK, SE=1 b/s/Hz250Gb/s: 10x 25-GHz-spaced 14.3-Gbaud TCM-PDM-QPSK, SE=1 b/s/Hz
Silicon-photonics based coherent PIC[P. Dong, X. Liu, S. Chandrasekhar, L. L. Buhl, R. Aroca, Y. Baeyens, and Y.-K. Chen, OFC’13, post-deadline paper PDP5C.6]
224-Gb/s PDM-16-QAM Modulator and Receiver based on Silicon Photonic Integrated Circuits
Compact transmitterCompact transmitterpCompact receiverScalablePotentially
pCompact receiverScalablePotentially integratable w/ DAC/driver/ADC/DSPFurther performance improvement and V
integratable w/ DAC/driver/ADC/DSPFurther performance improvement and Vimprovement and Vπ
reduction neededimprovement and Vπ
reduction needed
All Rights Reserved, Alcatel-Lucent42S. Chandrasekhar, IEEE Talk, April 2015
66 FlexibleFlexible--grid WDMgrid WDM66 FlexibleFlexible grid WDMgrid WDM
All Rights Reserved, Alcatel-Lucent43S. Chandrasekhar, IEEE Talk, April 2015
Agile networking via superchannels[Excerption from a presentation made by X. Liu, P. J. Winzer, and R. W. Tkach to DARPA on December 16, 2008]Al [S Ch d kh d X Li “T bit h l f hi h t l ffi i t i i ” ECOC’10 i it d T 3C 5]Also see: [S. Chandrasekhar and X. Liu, “Terabit superchannels for high spectral efficiency transmission,” ECOC’10, invited Tu3C.5]
Rate, Format, and Reach Agile Optical GroomingCurrent DWDM System
10Gb/s
stem
Rea
ch 10Gb/s40Gb/sDPSK
40Gb/sDQPSK
100Gb/sDQPSK
100Gb/sDP-QPSK
Current DWDM System3000km
Reduced guardband
Increased capacity
frequency50 GHz
Sys
Flexible-Band* OFDM** System
Increased capacity
4x10Gb/s
em R
each
1x40Gb/s
1x100Gb/s
10x10Gb/s
2x40Gb/s
1 Terabit/s 16QAM**-OFDM over 200-GHz
1 Terabit/s QPSK-OFDM over 400-GHz
w/ 2nd layer banding by coherent-WDM
frequency50 GHz
Syst
e
*: 1st layer banding by DSP in OFDM; 2nd layer banding by coherent-WDM**: PDM-QPSK assumed unless otherwise indicated
OFDM over 200 GHz
All Rights Reserved, Alcatel-Lucent44S. Chandrasekhar, IEEE Talk, April 2015
DARPA meeting, 12/16/2008
The flexible-grid DWDM standard[ITU-T G.694.1, “Spectral grids for WDM applications: DWDM frequency grid”, approved in June, 2012;http://www.itu.int/rec/T-REC-G.694.1-200206-S/en]
Details about the new ITU standard:Bandwidth granularity: 12.5 GHzCenter frequency granularity: 6.25 GHzq y g yThe allowed frequency slots have a nominal central frequency (in THz) defined by: 193.1 + n × 0.00625, where n is an integer
Any combination of frequency slots is allowed as long as no two frequency slots overlapThe flexible WDM architecture is supported by the recent availability of flexible-grid WSSs
All Rights Reserved, Alcatel-Lucent45S. Chandrasekhar, IEEE Talk, April 2015
pp y y g
Flexible-grid superchannel examples
2-Carrier-32.5Gbaud 400-Gb/s superchannelson a 87.5-GHz grid, supporting
20 Tb/s over the typical 4 4-THz C-band
5-Carrier-32.5Gbaud 1-Tb/s superchannelson a 200-GHz grid, supporting
22 Tb/s over the typical 4 4-THz C-band20 Tb/s over the typical 4.4-THz C-band
0
10
“S-Channel” 1 “S-Channel” 2 “S-Channel” 30
10
“S-Channel” 1 “S-Channel” 2 “S-Channel” 3
-5
0
5“S-Channel” 3“S-Channel” 2“S-Channel” 1
-5
0
5“S-Channel” 3“S-Channel” 2“S-Channel” 1
22 Tb/s over the typical 4.4-THz C-band
er (d
B)
er (d
B)
-20
-10
-20
-10
-25
-20
-15
-10
-25
-20
-15
-10
aliz
ed p
owe
aliz
ed p
owe
-40
-30
-175.0 -87.5 0 87.5 175.0
400G in 87.5-GHzSE = 4.6 b/s/Hz
-40
-30
-175.0 -87.5 0 87.5 175.0
400G in 87.5-GHzSE = 4.6 b/s/Hz
-40
-35
-30
-400 -300 -200 -100 0 100 200 300 400
1T in 200-GHzSE = 5 b/s/Hz
-40
-35
-30
-400 -300 -200 -100 0 100 200 300 400
1T in 200-GHzSE = 5 b/s/HzN
orm
a
Nor
ma
FREQUENCY (GHz)FREQUENCY (GHz) FREQUENCY OFFSET (GHz)FREQUENCY OFFSET (GHz)Frequency offset (GHz) Frequency offset (GHz)
The frequency spacing between adjacent superchannels is made to be sufficiently The frequency spacing between adjacent superchannels is made to be sufficiently
All Rights Reserved, Alcatel-Lucent46S. Chandrasekhar, IEEE Talk, April 2015
large to allow multiple passes through flexible-bandwidth-ROADMs large to allow multiple passes through flexible-bandwidth-ROADMs
Evolution of ROADM subsystems[S. Frisken, S. B. Poole, and G. W. Baxter, "Wavelength-Selective Reconfiguration in Transparent Agile Optical Networks,”P di f th IEEE l 100 5 1056 1064 M 2012]Proceedings of the IEEE , vol.100, no.5, pp.1056-1064, May 2012]
* CDC-f: Colorless, Directionless, Contentionless, and FlexgridWSS: Wavelength-Selective Switch; PLC: Planar Lightwave Circuit; ROADM: Reconfigurable Optical Add/Drop Multiplexer; AWG: Arrayed Waveguide Grating
All Rights Reserved, Alcatel-Lucent47S. Chandrasekhar, IEEE Talk, April 2015
AWG: Arrayed Waveguide Grating.
Flexible-grid-WSS[S. Frisken, S. B. Poole, and G. W. Baxter, Proceedings of the IEEE , vol.100, no.5, pp.1056-1064, May 2012]
stal
on
CoS
)Li
quid
cry
ssi
licon
(LC
The input is dispersed across a switch element, and the channel plan for switching wavelengths is defined by software and created by writing the appropriate phase image to the LCoS.
All Rights Reserved, Alcatel-Lucent48S. Chandrasekhar, IEEE Talk, April 2015
Measured pass-band spectra of a WSS employing a flexible grid with varying bandwidth.
Software-defined transmission in flexible-grid WDM[ S. Gringeri, N. Bitar, and T. J. Xia, "Extending software defined network principles to include optical transport,“C i ti M i IEEE l 51 3 32 40 M h 2013]Communications Magazine, IEEE , vol.51, no.3, pp.32,40, March 2013]
All Rights Reserved, Alcatel-Lucent49S. Chandrasekhar, IEEE Talk, April 2015
Illustration of a software-defined transceiver having several adjustable features
Capacity gain from superchannel on flexible grid[ P. Palacharla at OFC 2013 Workshop] [Courtesy of Drs. P. Palacharla, M. Sekiya, and X. Wang of Fujitsu Labs, USA]
Simulation Model Quasi-static traffic @ 400 Gb/s: demands with randomly chosen S-D pairsReference: Current network with fixed modulation (PDM-QPSK), inverse mux of 4x100GCase 1: Super-channel transmission with distance-adaptive modulation (4-carrier PDM-QPSK, 2-carrier PDM-16QAM) with fixed 50-GHz gridCase 2: Super-channel transmission with distance-adaptive modulation with flexible grid (ITU-T G 694 1 12 5-GHz granularity)
Capacity gains of 40~160%
(ITU T G.694.1, 12.5 GHz granularity)Capacity Gain (%) = (Capacity1,2 – Capacityref)/Capacityref
Capacity gains of 40 160% are achieved using flexible grid capability
Much lower capacity gains are obtained with fixed 50-GHz grid capability
All Rights Reserved, Alcatel-Lucent50S. Chandrasekhar, IEEE Talk, April 2015
77 Novel SuperchannelNovel Superchannel77 Novel Superchannel Novel Superchannel TechniquesTechniques
All Rights Reserved, Alcatel-Lucent51S. Chandrasekhar, IEEE Talk, April 2015
Multi-Tb/s superchannel with large-scale integration[X. Liu, S. Chandrasekhar, and P. J. Winzer, “Digital Signal Processing Techniques Enabling Multi-Tb/s SuperchannelT i i ” IEEE Si l P i M i 2014]Transmission”, IEEE Signal Processing Magazine, 2014]
OLOI1x’
Q1x’
ADCR Polarization-
PDDACI1x
Q1x PDMMulti-Tb/s superchannel
transmissionS1
Q1x
I1y’
Q1y’
ADC
ADC
ADC
R1Polarization-
DiversityOptical Hybrid
PD
PD
PD
y
DAC
DAC
DAC
y
1x
I1y
Q1y
λ1PDMI/Q
Modulator
FiberLink
S litt I
DS
P
AS
IC A
rray
DS
P
AS
IC A
rray
I CombinerWDMMUX
WDMDMUX
SplitterSM
OLO
IMx’
QMx’
IMy’
QMy’
ADC
ADC
ADC
ADCRM
Polarization-DiversityOptical Hybrid
PD
PD
PD
PD
DAC
DAC
DAC
DAC
IMx
QMx
IMx
λ1PDMI/Q
Modulator
Illustration of a multi-Tb/s superchannel transponder embedded in a WDM system (DSP: digital signal processor, preferably processing the entire superchannel as a whole)
OLO ADCPDDACQMy
All Rights Reserved, Alcatel-Lucent52S. Chandrasekhar, IEEE Talk, April 2015
( g g p p y p g p )
Joint DSPAs the constituents of a superchannel share the same optical transmission path theAs the constituents of a superchannel share the same optical transmission path, themonitoring of some transmission properties of the superchannel can be simplified
Carrier frequency recovery may be simplified[M. D. Feuer et al., “Joint digital signal processing receivers for spatial superchannels,” PTL 24, 1957-1960, 2012.]
Li t lk th h l tit t ld b t dLinear crosstalk among the superchannel constituents could be compensated[C. Liu et al., “Super receiver design for superchannel coherent optical systems,” Proc. SPIE 8284, Next-GenerationOptical Communication: Components, Sub-Systems, and Systems, 828405, 2012.]
Nonlinear crosstalk among the superchannel constituents could be partially compensated.[E Ip et al "Interchannel nonlinearity compensation for 3λ× 114 Gb/s DP 8QAM using three synchronized sampling[E. Ip et al., Interchannel nonlinearity compensation for 3λ× 114-Gb/s DP-8QAM using three synchronized samplingscopes," OFC’12, paper OM3A.6 (2012)][N. K. Fontaine, X. Liu, S. Chandrasekhar et al., "Fiber nonlinearity compensation by digital backpropagation of anentire 1.2-Tb/s superchannel using a full-field spectrally-sliced receiver," ECOC’13, paper Mo.3.D.5 (2013)][C. Xia, X. Liu, S. Chandrasekhar, N. K. Fontaine, L. Zhu and G. Li, "Multi-channel Nonlinearity Compensation of128-Gb/s PDM-QPSK Signals in Dispersion-Managed Transmission Using Dispersion-Folded Digital BackwardQ g p g g p gPropagation", OFC’14, paper Tu3A.5 (2014)]
The DSP efficiency of EDC may be improved.[K.-P. Ho, “Subband equaliser for chromatic dispersion of optical fibre,” Electronics Lett. 45, 1224-1226, 2009][A. Tolmachev and M. Nazarathy, “Filter-bank based efficient transmission of Reduced-Guard-Interval OFDM,” OpticsExpress, vol. 19, no. 26, pp. 370–384, 2011]
FEC gain could be increased through wavelength diversity by averaging PDL, OSNR, andnonlinear effects.
[J. Rahn et al., “Transmission improvement through dual-carrier FEC gain sharing,” OFC’13, paper OW1E.5, 2013][H Zh l “30 58 Tb/ i i 7 230 k i PDM h lf 4D 16QAM d d d l i i h 6 1
All Rights Reserved, Alcatel-Lucent53S. Chandrasekhar, IEEE Talk, April 2015
[H. Zhang et al., “30.58 Tb/s transmission over 7,230 km using PDM half 4D-16QAM coded modulation with 6.1b/s/Hz spectral efficiency” OFC’13, paper OTu2B.3, 2013.]
[N. K. Fontaine, X. Liu, S. Chandrasekhar et al., "Fiber nonlinearity compensation by digital backpropagation of an entire1 2 Tb/s superchannel using a full field spectrally sliced receiver " ECOC’13 paper Mo 3 D 5 (2013)]
Full-field spectrally sliced receiver1.2-Tb/s superchannel using a full-field spectrally-sliced receiver, ECOC 13, paper Mo.3.D.5 (2013)]
A 1.2-Tb/s 5-carrier quasi-Nyquist-WDM superchannel (PDM-16QAM) detected by 5 receivers each at 40 GSa/s, achieving both time and phase alignments.
A 1.2-Tb/s 5-carrier quasi-Nyquist-WDM superchannel (PDM-16QAM) detected by 5 receivers each at 40 GSa/s, achieving both time and phase alignments.
All Rights Reserved, Alcatel-Lucent54S. Chandrasekhar, IEEE Talk, April 2015
(This type of receiver can be used for SDM-superchannel as well)(This type of receiver can be used for SDM-superchannel as well)
[N. K. Fontaine, X. Liu, S. Chandrasekhar et al., ECOC’13, paper Mo.3.D.5 (2013)]
Joint fiber nonlinearity compensation
Transmission distance: 960 km in dispersion-uncompensated 80-km SSMF spans
(a) Nonlinearity compensation performance at 6-dBm superchannel launch power;(b) Nonlinearity compensation performance at 8-dBm superchannel launch power;(b) Nonlinearity compensation performance at 8 dBm superchannel launch power;(c) Q2 factor vs. signal launch power for EDC only, single-carrier DBP, and entire
superchannel DBP (showing the benefit of the joint DSP); and(d) Recovered constellation diagrams at 6-dBm launch power.
All Rights Reserved, Alcatel-Lucent55S. Chandrasekhar, IEEE Talk, April 2015
Tradeoff between performance and DSP complexity needs to be madeTradeoff between performance and DSP complexity needs to be made
Conclusion
To enable sustainable communication capacity growth, the cost per
information bit needs to be continuously reduced.
Superchannels, with their improved spectral efficiency and natural
compatibility with large-scale photonic/electronic integration, are
expected to be well suited to meet this demand.
Equipped with digital signal processing at both the transmitters and theEquipped with digital signal processing at both the transmitters and the
receivers, superchannel-based transmission may play a key role in the
future evolution of optical networks to support the ever-increasing
demand for internet traffic and cloud services and enable software-
defined optical networking.
All Rights Reserved, Alcatel-Lucent56S. Chandrasekhar, IEEE Talk, April 2015
Thank you all!
Backup Slides
All Rights Reserved, Alcatel-Lucent57S. Chandrasekhar, IEEE Talk, April 2015
SUPER-NYQUIST WDM – 3BUT EVEN HERE, SHANNON IS THE LIMIT,
10] 10
64-QAM256-QAM
y [b
/s/H
z]
ISI
16-QAM
4-QAMOver-filtering, Super-Nyquist
effic
ienc
y
[Cai et al., ECOC’10]
MAP
1
4 QAM
Spec
tral
e
[P J Wi JLT 2012]
0 5 10 15 20 25Required SNR per bit [dB]
S [P. J. Winzer, JLT, 2012]
COPYRIGHT © 2014 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
58
SPECTRAL EFFICIENCY – AND ITS PRICE IN SNR10z]
1
al e
ffic
ienc
yza
tion
[b/s
/H
~1 dB/year
10
Hz] 256
SE = log2 (1 + SNR)
0.01
0.1
Spec
tra
per
pola
riz
1990 1994 1998 2002 2006 2010
~1 dB/year
eff
icie
ncy
atio
n [b
/s/H
2x
2x16
64
41990 1994 1998 2002 2006Year
2010x-pol
y-pol
x-pol
y-pol 1
Spec
tral
per
pola
riza 2x4
Laser & filter stabilityModulation
PDMDetection
0 5 10 15 20 25Required SNR per bit [dB]
p
3.7 dB 8.8 dB
20 years ago: Device physics set engineeringlimits on spectral efficiency
T d I f ti th t f d t l
Simple on-off modulation,direct detectionHi h d d l i
PDM
COPYRIGHT © 2014 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
59
Today: Information theory sets fundamentallimits on spectral efficiency
Higher-order modulation,coherent detection