October 21, 2013 1
High capacity transmission over transoceanic distances with space-division-multiplexing
Itsuro Morita
KDDI R&D Laboratories Inc.,
October 21, 2013
Upcoming capacity crunch
2
October 21, 2013
Remaining orthogonal dimensions Space Division Multiplexing
Symbol rate spaceFrequency
imaginary
real
16QAMQPSK
e.g. 50 GHz space
Frequency(Wavelength)
QAMcos()sin() 256QAM
SpaceCore
single core multiple cores
SpaceMode
LP01 LP11a LP11b LP21a LP21b LP02 LP31bLP31a
Polarizationy
x Dual Pol.Single Pol.
3
TimeTimee.g. 10 Gbit/s 100 Gbit/s
October 21, 2013
Single-Core Fiber(SCF)
Multi-Core Fiber (MCF)Uncoupled MCF Coupled MCF
Single-Mode(SM)
Few-Mode(FM)
Multi-Mode(MM)
Optical fibers for SDM
4
October 21, 2013
MCF transmission experiments over 1000km
MCF: Multi-core (MC) fiberCDP: Capacity distance product
Fiber Amplifier Net bitrate[bit/s/fiber]
Distance[km]
CDP[Ebit/s·km] Year
7-coreMCF SC- EDFA 7.5T 2,688 0.020 ECOC2011 [7]
3-coreMCF SC- EDFA 1.0T 4,200 0.004 OFC2012 [8]
7-coreMCF MC-EDFA 28.8T 6,160 0.177 ECOC2012 [9]
7-coreMCF MC-EDFA 110.9T 6,370 0.706 2013 [10]
OPTICSEXPRESS
7-coreMCF MC-EDFA 140.7T 7,326 1.03 ECOC2013 [5]
12-coreMCF
MC-EDFA+Raman 688T 1,500 1.03 ECOC2013 [6]
SC-EDFA: Single-core EDFA, MC-EDFA: Multicore EDFA
October 21, 2013 6
Trans-oceanic class MCF transmission
Demonstration of trans-oceanic class space-division-multiplexing (SDM) transmission with MC-EDFA
40 x 128 Gbit/s transmission per core over 6,160km 7-core MCF- Total capacity : 28.8 Tbit/s per fiber- CDP : 177 Pbit/s・km
264 x 72 Gbit/s transmission per core over 6,370 km 7-core MCF- Total capacity : 111 Tbit/s per fiber- CDP : 707 Pbit/s・km
201 x 120 Gbit/s transmission per core over 7,326 km 7-core MCF- Total capacity : 140 Tbit/s per fiber- CDP : 1.03 Ebit/s・km
October 21, 2013 7
Trans-oceanic class MCF transmission
Demonstration of trans-oceanic class space-division-multiplexing (SDM) transmission with MC-EDFA
40 x 128 Gbit/s transmission per core over 6,160km 7-core MCF- Total capacity : 28.8 Tbit/s per fiber- CDP : 177 Pbit/s・km
264 x 72 Gbit/s transmission per core over 6,370 km 7-core MCF- Total capacity : 111 Tbit/s per fiber- CDP : 707 Pbit/s・km
201 x 120 Gbit/s transmission per core over 7,326 km 7-core MCF- Total capacity : 140 Tbit/s per fiber- CDP : 1.03 Ebit/s・km
October 21, 2013 8
7-core MCF
Cross-section of MCF
Parameter Value# of cores 7
Cladding diameter 200 μmCore pitch 56 μm
Effective area (Aeff) 99 μm2
Attenuation loss 0.188-0.200 dB/kmChromatic dispersion 18.4-18.7 ps/nm/km
Span length 55 kmTotal span loss
incl. Fan-in/Fan-out11.4 to 12.3 dB
Core #1 is center core
End face of fiber bundle
MCF
Thin Fibers
Fiber Bundle
Fan-in/Fan-out
October 21, 2013 9
7-core MC-EDFA
Cross-section of 7-core MC-EDF[1]
Parameter Value# of cores 7
Cladding diameter 180 μm
Core pitch 45 μm
Attenuation loss ~3.4 dB/m
Gain 15 dB
NF (typ.) incl. loss of Fan-in/out, WDM cpl. 7 dB
Gain and noise figure (NF)
Configuration
[1] Y. Tsuchida et al, ECOC2012, Tu4F2.
October 21, 2013 10
Crosstalk(XT) of MC-EDFA and MCF
XT of MC-EDFA (between 2 cores) XT of MCF (between 2 cores)
Core #1 is center core
Total XT of MC-EDFA at center core: < -46.5 dB (worst)
Total XT of MCF at center core : < -45.6 dB per span (worst)
Total XT per span at center core : < -43 dB per span (worst)e.g. Accumulated XT after 6,160 km transmission with 112 spans: < -22.5 dB
October 21, 2013
SWCore#1 in
#2 in
#3 in
#4 in
#5 in
#6 in
#7 in
GFF
GFF
GFF
GFF
GFF
GFF
PBC
AWGr
AWGr
ECL
DFB, ECL
Even ch.
Odd ch. 32 Gb/s PPGDATADelay
DATA
Delay
100‐50G IL
Delay
3dB
PMEI
Q
I
Q
IQM
IQM
……
Ch1Ch3
Ch39
Ch2Ch4
Ch40
Integrated pol.‐diverse hybrid Balanced
PDs
Real‐time oscilloscope
LO
ADC
ADC
ADC
ADC
Optical signal
11
Experimental setup
40 x 128-Gbit/s PDM-QPSK signals (SD-FEC with 20% OH) Received signal is processed offline 7 cores are connected sequentially using fan-in/fan-out[2]
[2]S. Chandrasekhar et al, ECOC2011, Th13C4.
TX RX
ECL: External cavity laserAWGr: Arrayed waveguide gratingIQM: IQ modulatorPME: Polarization multiplexing emulatorPBC: Polarization beam combinerGFF: Gain flatting filter
LO: Local oscillator ~100 kHz LWBalanced PD: Photo diodesADC: Analog/digital converter(50 GSa/s, 16 GHz bandwidth)
55 km MCF MC-EDFA
October 21, 2013 12
Transmission performance
Q-factor vs Transmission distance
The Q-penalty after transmission is about 1.4 dB The impact of XT is low even after 6,160 km transmission of MCF with
more than 100 MC-EDFAs
October 21, 2013 13
Transmission performance
After 6,160 km transmission
All of channels surpassed FEC limit [1] with Q-margin of 1 dB Total capacity : 7-core x 40ch x 103.125 Gbit/s(net) = 28.8 Tbit/s per fiber CDP :177 Pbit/s x km
1550.116 nm 1558.173 nm 1565.905 nm
FEC limit = 6.4 dB
October 21, 2013 14
Trans-oceanic class MCF transmission
Demonstration of trans-oceanic class space-division-multiplexing (SDM) transmission with MC-EDFA
40 x 128 Gbit/s transmission per core over 6,160km 7-core MCF- Total capacity : 28.8 Tbit/s per fiber- CDP : 177 Pbit/s・km
264 x 72 Gbit/s transmission per core over 6,370 km 7-core MCF- Total capacity : 111 Tbit/s per fiber- CDP : 707 Pbit/s・km
201 x 120 Gbit/s transmission per core over 7,326 km 7-core MCF- Total capacity : 140 Tbit/s per fiber- CDP : 1.03 Ebit/s・km
October 21, 2013 15
D
D
24GS/sAWG
IQM
IQM
Odd
Even
IQM132 lasers
37.5GHz space
8 lasers37.5GHz space
8 lasers37.5GHz space
IQM
18.75GHz
24GS/sAWG
Loading
PME
SW
GFF
GFF
GFF
core1
core2
core7
SW
1S
W7
SW
2
1x8
split
ter
Pol.-diversityoptical hybrid
BPDBPD
BPDBPD
Real-timeoscilloscope ECL
OBPF
7:1
switc
h
46 km MCFMC-EDFA
7 x 264 channel x 72 Gbit/s (111 Tbit/s) quasi-Nyquist-WDM PDM-QPSK signal transmission over 6,370 km
TX
RX
Experimental setup
October 21, 2013 16
5 10 2015OSNR (noise in 0.1 nm) [dB]
Single ChannelWDM
BER
10-1
10-2
10-3
10-4
10-610-5
20100-20 -10
Pow
er [1
0dB
/div
]
Frequency [GHz]
18GHz
WDM
Single channel
Quasi-Nyquist-WDM PDM-QPSK signal
Bit rate : 128 Gbit/s → 72 Gbit/sSpectral Efficiency : 2 bit/s/Hz → 3.2 bit/s/Hz
October 21, 2013 17
7-core MCF
Parameter Value# of cores 7
Cladding diameter 196 μm
Core pitch 56 μm
Effective area (Aeff) 99 → 121 μm2
Attenuation loss 0.196-0.200 dB/km
Chromatic dispersion 18.4-18.7 ps/nm/km
Span length 55 → 45.5 kmTotal span loss
incl. Fan-in/Fan-out11.4 - 12.3 dB
→ 9.9 – 10.5 dB
2
13
5 4
6
7
trench index core profile0.40.2
0-0.2-0.4
-0.8-0.6
[%
]
0-20 -10 2010r [µm]
October 21, 2013 18
-80
-70
-40
-50
-60
Cro
ssta
lk [d
B]
2-1
2-4
2-6
1-3
1-5
1-71-
21-
41-
6
2-3
2-5
2-7 3-
1
3-6
3-4
3-2
3-5
3-7 4-
1
4-6
4-3
4-2
4-5
4-7 5-
1
5-6
5-3
5-2
5-4
5-7 7-
1
7-5
7-3
7-2
7-4
7-66-
1
6-5
6-3
6-2
6-4
6-7
Pair of cores
1550 nm
Crosstalk of MCF
Total XT of MCF at center core per span : < -45.6 dB → -51 dB
October 21, 2013 19
core1 core2core6core5
core4core7core3
05
10
15
25
20
3
4
5
7
6
NF
[dB
]G
ain
[dB
]
1530 1540 15601550Wavelength [nm]
7-core MC-EDFA
Single stage configuration→ Two stage configuration for higher output power- Bandwidth: 1.9 THz → 5 THz
NF<5.5dB
October 21, 2013 20
191 192 193 194 196195
周波数 [THz]
4
6
8
Q値
[dB]
FEC threshold : 5.9 dB
2
光パワー
[10dB
/div]
core1 core2core6core5
core4core7core3
Qfa
ctor
[dB
]
Frequency [THz]
Opt
ical
Pow
er [
10dB
/div
]
Capacity-Distance Product : 707 [Pbit/s x km]
Transmission performance
After 6,370 km transmission
October 21, 2013 21
Trans-oceanic class MCF transmission
Demonstration of trans-oceanic class space-division-multiplexing (SDM) transmission with MC-EDFA
40 x 128 Gbit/s transmission per core over 6,160km 7-core MCF- Total capacity : 28.8 Tbit/s per fiber- CDP : 177 Pbit/s・km
264 x 72 Gbit/s transmission per core over 6,370 km 7-core MCF- Total capacity : 111 Tbit/s per fiber- CDP : 707 Pbit/s・km
201 x 120 Gbit/s transmission per core over 7,326 km 7-core MCF- Total capacity : 140 Tbit/s per fiber- CDP : 1.03 Ebit/s・km
October 21, 2013
Experimental Setup
GFF
GFF
GFF
45.5km MCFMC-EDFA
core1
core2
core7
SW
1S
W7
SW
2
Pow
er S
plitt
er
Pol.-diversityoptical hybrid
BPD
BPD
BPD
BPDReal-time
oscilloscopeECL
OBPF
7:1
switc
h
25GHz
Frequency
30GBaud
25GHz-spaced 201-WDM100Gbit/s DP-QPSK
with duobinary-pulse shaping(20%-overhead SD-FEC)
D
D
50GS/sAWG
IQM
IQM
Odd
Even
MZM101 lasers50GHz space
8 lasers25GHz space
8 lasers25GHz space
IQM
12.5GHz
t
t
t
50GS/sAWG
LoadingSWWSS
WSS
WSS
OSAPC
PME
PM
E
22
7 x 201 channel x 100 Gbit/s (140.7 Tbit/s) super-Nyquist-WDM signal transmission over 7,326 km
October 21, 2013
Duobinary-Pulse Shaping andMaximum-Likelihood Sequence Estimation
Duobinary-pulse shaping
Impu
lse
resp
onse
Time [1/baudrate/div]
OSNR
IQ map
DP-QPSK
after duobinarypulse shaping
2-3dB
Proposed by J. Li et al., J. Lightwave Technol., 30, 1664 (2012) [13].
sincfunction
delayedsinc
function
Q fa
ctor
MLSE
1
00/0
1/1
1/2
0/1
0/0
1/1
1/2
0/1
0/0
1/1
t = 0 t = 1/B t = 3/Bt = 2/B
Duobinary trellis
23
October 21, 2013
Back-to-Back Performance
Measured Bit-Error RatesOptical spectra of signalsP
ower
[10d
B/d
iv]
Duobinary-pulse shaping
Nyquist-pulse shapingSpectral overlap
Frequency [25GHz/div]
SC
SC
WDM
WDM
10 15 2520OSNR [dB]
WDMSC
WDMSC10-1
10-2
10-3
10-4
10-5
10-710-6
BE
R
Duobinary pulse shaping
Nyquist pulse shaping
Duobinary pulse shaping can suppress WDM crosstalk from adjacent channels.The penalty is around 2 dB compared with single-channel DP-QPSK.
Baudrate : 30GBaudWDM spacing : 25GHz
24
October 21, 2013
Transmission Performance
Q2 factors for all 1,407 channels (201-WDM, 7-Core) > 6.0dB
9
8
7
6
5
Q2
fact
or [d
B]
core1 core2core6core5core4
core7
core3
FEC threshold : 5.9 dB [14]
191 192 193 194 196195Frequency [THz]
Capacity-Distance Product : 1.03 [Exabit/s x km] 25
After 7,326 km transmission
October 21, 2013
10 100
Transmission Experiments over 10Tbit/s・1,000km
10,000
Capacity per fiber [Tbit/s]
Dis
tanc
e [k
m]
1,000
1,000
5,000
2,000
High-capacity transmission experiments
Multi-core fiberSingle-core fiber
26
October 21, 2013 27
Reduction of power consumption
Multiple cores pumped by multimode LD w/o temp. control
Single Pump
Multiple-Pumps
Core in MC-EDFAPow
er C
onsu
mpt
ion Core pumped
MC-EDFA
Signals
Signals
Cladding pumped MC-EDFA
October 21, 2013 28
Summary
Demonstration of trans-oceanic class space-division-multiplexing (SDM) transmission with MCF and MC-EDFA
40 x 128 Gbit/s transmission over 6,160 km- Total capacity : 28.8 Tbit/s per fiber- CDP : 177 Pbit/s・km
264 x 72 Gbit/s transmission over 6,370 km- Total capacity : 111 Tbit/s per fiber- CDP : 707 Pbit/s・km
201 x 120 Gbit/s transmission over 7,326 km- Total capacity : 140 Tbit/s per fiber- CDP : 1.03 Exabit/s・km
October 21, 2013 29
Thank you !!
The part of this work was supported by “Research on Innovative Optical Fiber Technology” and
“R&D of Innovative Optical Communication Infrastructure”The author thanks NEC Corporation and Furukawa Electric Co.,
Ltd. for their contributions.