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© 2014 Xtera Communications, Inc. Proprietary & Confidential
Maximizing Network Capacity, Reach and Value Over land, under sea, worldwide
1
Invited Paper
Advanced Technologies for Unrepeatered Transmission Systems and Their Applications
Do-il Chang, Wayne Pelouch, Sergey Burtsev, Bertrand Clesca, Philippe Perrier, Herve Fevrier
Xtera Communications, Inc.
13 November 2014
Asia Communications and Photonics (ACP) Conference 2014 (Shanghai, China) – ATh4E.4
© 2014 Xtera Communications, Inc. Proprietary & Confidential 2
• Introduction – Unrepeatered transmission system and applications
– Key technologies
– Summary of recent unrepeatered transmission results
• Experimental demonstrations of unrepeatered transmission – Distributed Raman pump modules / 100G cards
– 557 km unrepeatered 100G transmission
– 15 Tbit/s unrepeatered transmission
• Applications in submarine / terrestrial systems – 8 x 120 Gbit/s transmission over a cascade of two spans
(59.7 dB + 60.8 dB)
– Applications in terrestrial network
• Summary
Content
© 2014 Xtera Communications, Inc. Proprietary & Confidential 3
Unrepeatered System and Applications
© 2014 Xtera Communications, Inc. Proprietary & Confidential 4
• System that operates without active element between the terminals – No in-line amplifiers, no repeaters, no regenerators
• Typical operational conditions – Fiber type: Legacy (SMF, PSCF, NZDSF)
New installation (Ultra low loss, large effective core area fiber)
• Distance (with 100G): 100 km to 560 km, span loss: 40 dB to 90 dB
• Applications – Communication between islands or main lands
Unrepeatered Transmission System
Passive fiber cable
© 2014 Xtera Communications, Inc. Proprietary & Confidential 5
• System that operates without active element between the terminals – No in-line amplifiers, no repeaters, no regenerators
• Typical operational conditions – Fiber type: Legacy (SMF, PSCF, NZDSF)
New installation (Ultra low loss, large effective core area fiber)
• Distance (with 100G): 100 km to 560 km, span loss: 40 dB to 90 dB
• Applications – Communication between islands or main lands
– Communication for oil platforms (oil & gas industry)
Unrepeatered Transmission System
© 2014 Xtera Communications, Inc. Proprietary & Confidential 6
• System that operates without active element between the terminals – No in-line amplifiers, no repeaters, no regenerators
• Typical operational conditions – Fiber type: Legacy (SMF, PSCF, NZDSF)
New installation (Ultra low loss, large effective core area fiber)
• Distance (with 100G): 100 km to 560 km, span loss: 40 dB to 90 dB
• Applications – Communication between islands or main lands
– Communication for oil platforms (oil & gas industry)
– Skipping intermediate sites in hostile areas (tropical forest, desert...)
Unrepeatered Transmission System
Communication using high-voltage transmission towers with Optical Ground Wire (OPGW) cable
© 2014 Xtera Communications, Inc. Proprietary & Confidential 7
• System that operates without active element between the terminals – No in-line amplifiers, no repeaters, no regenerators
• Typical operational conditions – Fiber type: Legacy (SMF, PSCF, NZDSF)
New installation (Ultra low loss, large effective core area fiber)
• Distance (with 100G): 100 km to 560 km, span loss: 40 dB to 90 dB
• Applications – Communication between islands or main lands
– Communication for oil platforms (oil & gas industry)
– Skipping intermediate sites in hostile areas (tropical forest, desert...)
Unrepeatered Transmission System
Communication using high-voltage transmission towers with Optical Ground Wire (OPGW) cable
OPGW Cable and Amazon River Crossing
© 2014 Xtera Communications, Inc. Proprietary & Confidential 8
Key Technologies in Unrepeatered Transmission
© 2014 Xtera Communications, Inc. Proprietary & Confidential 9
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Fiber attenuation
Amplifier power boost
Noise limitation
Non-linear limitations • SPM, XPM • FWM • SBS • Polarization X-talk
Noise limitation • OSNR requirement
© 2014 Xtera Communications, Inc. Proprietary & Confidential 10
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Fiber attenuation
Amplifier power boost
Noise limitation
© 2014 Xtera Communications, Inc. Proprietary & Confidential 11
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Fiber attenuation
Amplifier power boost
Noise limitation
Increase the threshold of non-linear limitation • Large core effective area fiber • Digital nonlinear mitigation • Polarization interleaving (RZ)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 12
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Fiber attenuation
Amplifier power boost
Noise limitation
Increase the threshold of non-linear limitation • Large core effective area fiber • Digital nonlinear mitigation • Polarization interleaving (RZ)
Reduce the threshold of noise limitation • Stronger FEC
© 2014 Xtera Communications, Inc. Proprietary & Confidential 13
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Fiber attenuation
Amplifier power boost
Noise limitation
Increase the threshold of non-linear limitation • Large core effective area fiber • Digital nonlinear mitigation • Polarization interleaving (RZ)
Reduce the threshold of noise limitation • Stronger FEC
Lower fiber attenuation
© 2014 Xtera Communications, Inc. Proprietary & Confidential 14
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
© 2014 Xtera Communications, Inc. Proprietary & Confidential 15
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
Optical gain created within the line fiber by distributed Raman amplification
Pump power is limited by MPI penalty or lasing
© 2014 Xtera Communications, Inc. Proprietary & Confidential 16
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
© 2014 Xtera Communications, Inc. Proprietary & Confidential 17
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
Forward pump power is limited by RIN, MPI penalty
© 2014 Xtera Communications, Inc. Proprietary & Confidential 18
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
© 2014 Xtera Communications, Inc. Proprietary & Confidential 19
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
ROPA*
* Remote Optically- Pumped Amplifier
Pump power is limited by MPI penalty or lasing
Gain from ROPA
Residual pump power
© 2014 Xtera Communications, Inc. Proprietary & Confidential 20
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
ROPA
© 2014 Xtera Communications, Inc. Proprietary & Confidential 21
Channel Power Management in Unrepeatered
Transmission
Distance
Per
channel pow
er
pro
file
Non-linear limitation
Noise limitation
ROPA ROPA
Gain from ROPA (Forward)
Forward pump power is limited by RIN, MPI penalty
Residual pump power
© 2014 Xtera Communications, Inc. Proprietary & Confidential 22
• Higher order can provide better performance
• Requires much stronger pump (> 5 W for 3rd order pumping)
Further Improvement: High-Order Raman Pump
Distance
Per
channel pow
er
pro
file
Noise limitation
ROPA
Final pump is developed within the span
Within MPI limitation
Non-linear limitation
Xtera system uses 1st ~ 2nd order pumping
1455 1360 1280 nm
© 2014 Xtera Communications, Inc. Proprietary & Confidential 23
• Higher order can provide better performance
• Requires much stronger pump (> 5 W for 3rd order pumping)
Further Improvement: High-Order Raman Pump
Distance
Per
channel pow
er
pro
file
Noise limitation
ROPA
Final pump is developed within the span
Within MPI limitation
Non-linear limitation
Xtera system uses 1st ~ 2nd order pumping
1455 1360 1280 nm
7W
OFC 2005, OThF4
Pump power : 7W
© 2014 Xtera Communications, Inc. Proprietary & Confidential 24
Fiber Type ROPA Length (Km) Loss (dB)
ALU, ECOC 2009 2.626x112 Gb/s
(50GHz)PDM-QPSK Offline E-PSCF (115mm2) YES 401 67 1.04
Corning, ECOC 2010 4.040x112 Gb/s
(50GHz)PM-QPSK Offline
EX1000, 2000, Dev
(76mm2, 112mm2, 128mm2)No 365 59.6 1.46
ALU, ECOC 2010 0.164x43 Gb/s
(100GHz)PDM-RZ-BPSK Offline EX2000 (115mm2) Yes 525 84 0.08
ALU, OFC 2011 2.5664x43 Gb/s
(50GHz)PDM-RZ-BPSK Offline E-PSCF (115mm2) Yes 440.7 71.5 1.13
Bell Labs, ALU, OFC 2011 0.88x112 Gb/s
(50GHz)PDM-iRZ-BPSK Offline NZDSF (LEAF) No 300 66 0.24
Xtera, ECOC 2011 0.88x120 Gb/s
(100GHz)PM-NRZ-QPSK Offline Z (Legacy, 76mm2) Yes 444.2 76.6 0.36
ALU, ECOC 2011 0.44x100 Gb/s
(50GHz)PDM-QPSK Real Time
ULA-PSCF, E-PSCF
(135mm2, 115mm2)Yes 462 76.9 0.18
Fujitsu, ECOC 2011 1680x224 Gb/s
(50GHz)DP-16QAM (50GHz) Offline Large Aeff PSCF (133mm2) No 240 39.1 3.84
Xtera, ECOC 2012 3.434x120 Gb/s
(50, 100GHz)PM-NRZ-QPSK Real Time Z (Legacy, 76mm
2) Yes 432.8 74.4 1.47
ALU, ECOC 2012 6.060x100 Gb/s
(40GHz)PDM-RZ-QPSK Offline
ULA-PSCF, E-PSCF
(135mm2, 115mm
2)
Yes 437 71.0 2.62
Z (Legacy, 76mm2) 383.5 66.7 0.46
SMF (Legacy, 80mm2) 342.7 66.8 0.41
Xtera, OFC 2013 0.88x120 Gb/s
(100GHz)PM-QPSK Real Time
Z, EX2000
(76mm2, 112mm2)Yes 480.4 80.8 0.38
OFS, OFC 2013 3.2 32x120 Gb/s PDM-NRZ-QPSK OfflineULAF1, ULAF2, AW
(150mm2, 125mm
2, 80mm
2)
Yes 445 79.0 1.42
ALU, ECOC 2013 1.61x400 Gb/s +
12x100 Gb/s
PDM-NRZ-16QAM,
PDM-RZ-QPSKOffline
ULA-PSCF, E-PSCF
(135mm2, 115mm2)Yes 401 65.5 0.64
OFS, OFC 2014 6.3 63x128 Gb/s PDM-NRZ-QPSK OfflineULAF1, ULAF2, AW
(150mm2, 125mm2, 80mm2)Yes 402 ? 2.53
0.1 1 x120 Gb/s 556.7 90.2 0.06
0.44 x120 Gb/s
(100GHz)523.2 84.8 0.21
Offline EX3000 (152mm2) 286 44.5 2.29
OfflineEX3000, EX2000
(152mm2, 110mm2)292 45.5 2.34
OfflineEX3000, EX2000
(152mm2, 110mm
2)
304 47.4 2.43
ALU, ECOC 2014 8.0 40x200 Gb/s PDM-16QAM Real TimeULA-PSCF, E-PSCF
(135mm2, 115mm2)Yes 363 59.1 2.90
No 333.6 55.4 5.00
Yes 389.6 64.3 5.84
No
Xtera, Corning
ECOC 201415
150x120 Gb/s
(50GHz)PM-RZ-QPSK Real Time SMF-ULL (80mm2)
Corning, OpticsExpress 2014 8.040x256 Gb/s
(50GHz)PDM-16QAM
Xtera, Verizon, Corning
OFC 2014 (PD)PM-iRZ-QPSK Real Time
EX2000 (112mm2) fiber cable in
OSP Environment
Forward and
Backward
Capacity x
Reach
(Pb/s Km)
No
Reference
Total
Capacity
(Tb)
No CHs x Bit
rate (ch
spacing)
Signal FormatCoherent
Processing
Span Info
Xtera, IPC 2012 1.212x120 Gb/s
(100GHz)PM-NRZ-QPSK Real Time
Recent Unrepeatered Transmission Results
300
350
400
450
500
550
600
2008 2009 2010 2011 2012 2013 2014 2015
Dis
tan
ce (
Km
)
Year
OFS
AlcaLu
Corning
Xtera
0
1
2
3
4
5
6
2008 2009 2010 2011 2012 2013 2014 2015
Cap
acit
y x
Rea
ch (
Pb
/s -
Km
)
Year
OFS
AlcaLu
Corning
Fujitsu
Xtera
* with coherent signal processing
© 2014 Xtera Communications, Inc. Proprietary & Confidential 25
Experimental Demonstrations of Unrepeatered Transmission
© 2014 Xtera Communications, Inc. Proprietary & Confidential 26
• Basic features – Commercially available
– Consists of five pump wavelengths distributed in the spectral range between
1420 and 1500 nm
– Uses polarization balanced and wavelength multiplexed laser diodes
(RIN < -105 dB/HZ)
– Total pump power < 1.8 W
– Uses commercial high power connector (Diamond, E2000PS) to connect
span
Distributed Raman Pumps: Nu-Wave OptimaTM SE24
from span
ES2000PS
© 2014 Xtera Communications, Inc. Proprietary & Confidential 27
• Flexible operation – Can be used in forward or backward pumping scheme
– Can provide flexible gain profiles based on the application (C, L, Wide-band,
w/wo ROPA etc..)
– Can increase pump power (up to ~ 2.6W) by using power expansion module
(e.g. Large Aeff fiber)
Distributed Raman Pumps: Nu-Wave OptimaTM SE24
C-band L-band Wide-band (61nm)
Wide-band (61nm) with ROPA
ROPA
© 2014 Xtera Communications, Inc. Proprietary & Confidential 28
• 100G line card – Modulated at 120 Gbit/s
PM-QPSK
– 15% overhead SD-FEC
(FEC threshold: 6.4dB)
– Real-time ASCI processing
• 100G comb modulator – Modified 100G line card
– Receives CW comb signals and
outputs 120 Gbit/s PM-QPSK
(15% overhead)
100G Line Card / 100G Comb Modulator
© 2014 Xtera Communications, Inc. Proprietary & Confidential 29
557 km Unrepeatered 100G Transmission with Commercial Raman DWDM System, Enhanced ROPA, and Cabled Large Aeff
Ultra-Low Loss Fiber in OSP Environment
OFC 2014, Post-Deadline Paper Th5A.7 IEEE Journal of Lightwave Technology (to be published 2015)
• Enhanced ROPA configuration • Cabled fiber in uncontrolled OutSide Plant (OSP) Environment • Longest 100G unrepeatered transmission up to date
© 2014 Xtera Communications, Inc. Proprietary & Confidential 30
Enhanced ROPA configuration
ROPA
ROPA
Backward ROPA configuration
Signal
Signal
© 2014 Xtera Communications, Inc. Proprietary & Confidential 31
Forward + Backward ROPA configuration
Enhanced ROPA configuration
ROPA
ROPA F-ROPA
F-ROPA
Signal
Signal
© 2014 Xtera Communications, Inc. Proprietary & Confidential 32
• Remote optically pumped amplifiers in two directions in same enclosure
• Residual pump powers from other direction help signal going further.
Enhanced ROPA configuration
ROPA
ROPA F-ROPA
F-ROPA
Signal
Signal
© 2014 Xtera Communications, Inc. Proprietary & Confidential 33
• 100G channels: 120 Gbit/s PM-QPSK (15% overhead, 6.4 dB Q SD-FEC threshold)
• BER is measured by 100G line card with real-time ASIC processing.
• Forward and Backward distributed Raman: commercial Nu-Wave OptimaTM SE24 + HP extension
• Residual pump sharing in unidirectional transmission
• Spans consist of Corning® Vascade® EX2000 (G.654B) fiber with Aeff=112 µm2.
• Distance between ROPAs: – Case 1: 289.3 km (total 556.7 km) for 1 x 100G channel transmission
– Case 2: 255.8 km (total 523.2 km) for 4 x 100G channels transmission
System Configuration
100G MXP l1
100G MXP l2
100G MXP l3
100G MXP l4
WSS
DCU
EOA Distance between ROPAs*
ROPA (F)
133.7 km
EOA
ROPA (B)
Residual pump
sharing
WSS
Forward Raman
Backward Raman
100G MXP l1
100G MXP l2
100G MXP l3
100G MXP l4
133.7 km
ROPA (B)
ROPA (F)
P’
p
© 2014 Xtera Communications, Inc. Proprietary & Confidential 34
• Cable: 8.3 km Altos gel filled loose tube cable on a 0.9 m diameter spool
• Corning® Vascade® EX2000 (G.654B), Aeff=112 µm2
• Span: 556.7 km, total loss 90.2 dB
• Spliced fiber attenuation: 0.162 dB/km
Corning® Vascade® EX2000 Cabled Optical Fiber Deployed Outside the Lab
0%
20%
40%
60%
80%
100%
0.15 0.155 0.16 0.165 0.17 0.175 0.18
Cu
mm
ula
tive
Pro
bab
lity
(%)
Attenuation at 1550 nm (dB/km)
CableFiber
• Nominal outer diameter: 16.0 mm • Min. bend radius installation: 240 mm • Min. bend radius operation: 160 mm • Fiber length in the cable: 8.1 to 8.5 km (average 8.3 km)
Vascade® EX2000 drum
© 2014 Xtera Communications, Inc. Proprietary & Confidential 35
• Pump powers – Forward: 2,510 mW
– Backward: 2,520 mW
• OSNR – Measured: 13.7 dB/0.1nm
– Simulated: 13.6 dB/0.1nm
• Measured Q: 6.54 dB (BER = 1.65 x 10-2)
1 x 100G Transmission over 556.7 km
-50
-45
-40
-35
-30
-25
-20
1558 1560 1562 1564 1566 1568
Pow
er
(dB
m)
Wavelength (nm)
Input-0.2nm RBW
Output-0.2nm RBW
Measured OSNR :
13.7dB (0.1 nm)
Forward ROPA gain : 4.6 dB Backward ROPA gain : 19.4 dB Simulated OSNR : 13.6 dB
Signal Z Profile
Pump Z Profiles
Remaining power from Raman for EDF: 6.6 mWResidual power for use in other direction: 0.6 mW
Remaining power from Raman for EDF: 8.6 mWResidual power for use in other direction: 2.7 mW
Forward pumps Backward pumps
© 2014 Xtera Communications, Inc. Proprietary & Confidential 36
• Pump powers – Forward: 2,690 mW
– Backward: 2,520 mW
• OSNR – Measured: 14.2 dB/0.1nm
• Measured Q: 6.9 dB (BER = 1.4 x 10-2)
4 x 100G Transmission over 523.2 km
Forward ROPA gain : 2.6 dB
Backward ROPA gain : 20.4 dB
Signal Z Profile
Pump Z Profiles
Residual forward pump : 5.1mW
Residual backward pump : 8.6mW
10
11
12
13
14
15
-50
-40
-30
-20
-10
0
1558 1560 1562 1564 1566
OS
NR
(d
B)
Po
we
r (d
Bm
)
Wavelength (nm)
Input-0.2nm RBW
Output-0.2nm RBW
OSNR (Sim.)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 37
Long Term Stability Test
1.2E-02
1.3E-02
1.4E-02
1.5E-02
1.6E-02
1.7E-02
1.8E-02
1.9E-02
2.0E-02
0.0 2.0 4.0 6.0 8.0 10.0
BE
R
Hours
1563.86 nm 1563.05 nm
1562.23 nm 1561.42 nm
SD-FEC Threshold
1.60E-02
1.65E-02
1.70E-02
1.75E-02
1.80E-02
1.85E-02
1.90E-02
1.95E-02
0 10 20 30 40 50 60
BE
R
Hours
BER before SD-FEC
SD-FEC Threshold
4 x 100G Transmission over 523.2 km
1 x 100G Transmission over 556.7 km
© 2014 Xtera Communications, Inc. Proprietary & Confidential 38
150 x 120 Gbit/s Unrepeatered Transmission over 333.6 km and 389.6 km (with ROPA) G.652 Fiber
ECOC 2014, Paper Tu.1.5.4
• G.652 fiber with standard core area fiber • Highest Capacity x Reach (5.84 Pbit/s km) unrepeatered
transmission up to date
© 2014 Xtera Communications, Inc. Proprietary & Confidential 39
• LRA: (Wide-band) Lumped (discrete) Raman Amplifier – LRA-2 provides average -670 ps/nm pre-dispersion compensation.
• 100G channels: 120 Gbit/s PM-QPSK (15% overhead, 6.4 dB Q SD-FEC threshold)
• BER is measured by 100G line card with real-time ASIC processing.
• Forward and backward distributed Raman: commercial Nu-Wave OptimaTM SE24
• Spans consist of Corning® SMF-28® ULL fiber (G.652B) fiber. – Without ROPA: 333.6 km (55.4dB), Accumulated dispersion: +4,300 ps/nm (average)
– With ROPA: 389.6 km (64.3dB)
• ROPA (Isolator + 12m erbium) is located 116.7 km form RX.
• Accumulated dispersion : + 5,150 ps/nm (average)
System Configuration
45 C-Band
(odd) DFBs
30 L-Band
(odd) DFBs
45 C-Band
(even) DFBs
30 L-Band
(even) DFBs
100G
Comb
100G
Comb
100 GHz PM-AWG
: PM 3dB (50/50) coupler : 3 dB (50/50) coupler
WSS
C-100G MXP
C-100G MXP
L-100G MXP
WSS
C-100G MXP
C-100G MXP
L-100G MXP
Backward Raman
Forward Raman
Span without ROPA 333.6 km (55.4 dB)
Span with ROPA 389.6 km (64.3 dB)
ROPA
116.7 km 272.9 km
LRA-1 LRA-2 LRA-3
© 2014 Xtera Communications, Inc. Proprietary & Confidential 40
-25
-20
-15
-10
-5
0
5
1525 1535 1545 1555 1565 1575 1585 1595
Pow
er
(dB
m)
Wavelength (nm)
-25
-20
-15
-10
-5
0
5
1525 1535 1545 1555 1565 1575 1585 1595
Po
we
r (d
Bm
)
Wavelength (nm)
5
7
9
11
13
15
17
1525 1535 1545 1555 1565 1575 1585 1595
OS
NR
an
d Q
(d
B)
Wavelength (nm)
Measured OSNR
Simulated OSNR
Q before FEC(dB)
SD-FEC Threshold
• Input signals – Channels are pre-emphasized to provide flat Q over spectrum at receive side.
– Average power into span: -9.8 dBm/channel
• At receiver – Ripple is flattened by WSS.
– Average OSNR: 14.5 dB, average Q: 7.1 dB
– All channels are error free after SD-FEC.
Transmission Over 333.6 km SMF-28® ULL Fiber Without ROPA
Input to the Span (LRA-2 Out)
At the RX (LRA-3 Out)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 41
Transmission Over 333.6 km SMF-28® ULL Fiber Without ROPA
Signal Z Profile
Pump Z Profiles
Forward Pump Power : 1590 mW Backward Pump Power : 1670 mW
Max Signal power : +8.9 dBm at 21.7 Km
Forward Raman gain Includes ~ 28 dB span loss
Back Raman gain Includes ~ 28 dB span loss
• Raman gain (On/Off) • Forward: 19.3 dB • Backward: 30.5 dB
• Noise Figure includes 55.8 dB span loss • 34.6 dB (Effective NF < -21 dB)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 42
5
7
9
11
13
15
17
1525 1535 1545 1555 1565 1575 1585 1595
OS
NR
an
d Q
(d
B)
Wavelength (nm)
Measured OSNR
Simulated OSNR
Q before FEC(dB)
SD-FEC Threshold
-25
-20
-15
-10
-5
0
5
1525 1535 1545 1555 1565 1575 1585 1595
Pow
er
(dB
m)
Wavelength (nm)
-25
-20
-15
-10
-5
0
5
1525 1535 1545 1555 1565 1575 1585 1595
Pow
er
(dB
m)
Wavelength (nm)
• Input signals – Channels are pre-emphasized to provide flat Q over spectrum at receive side.
– Average power into span: -10.8 dBm/channel
• At receiver – Ripple (~10dB) is flattened by WSS.
– Average OSNR: 14.1 dB, average Q: 6.7 dB
– All channels are error free after SD-FEC.
Transmission Over 389.6 km SMF-28® ULL Fiber With ROPA
Input to the Span (LRA-2 Out)
At the RX (LRA-3 Out)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 43
Signal Z Profile
Pump Z Profiles
Forward Pump Power : 1590 mW Backward Pump Power : 1790 mW
Max Signal power : +8.1 dBm at 21.3 Km
Forward Raman gain Includes ~ 50 dB span loss
Back Raman gain Includes ~ 28 dB span loss
Transmission Over 389.6 km SMF-28® ULL Fiber With ROPA
ROPA Gain
Residual Pump at ROPA : 11.5 mW
Noise Figure includes 64.3 dB span loss 34.6dB (Effective NF < -30 dB)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 44
Unrepeatered Transmission Applications in Submarine / Terrestrial Systems
© 2014 Xtera Communications, Inc. Proprietary & Confidential 45
8 x 120 Gbit/s Transmission Over a Cascade of Two Spans With a Total Loss in Excess of 120 dB
OFC/NFOEC 2013, Paper NM2E.6
• Advanced configuration for the cascade of long spans • 8 x 120 Gbit/s transmission over SMF 305.5 km with 59.7 dB and
PSCF 342.9 km with 60.8dB • Achieved with standard core effective area fiber
© 2014 Xtera Communications, Inc. Proprietary & Confidential 46
Objectives & Background
Intermediate site PoP
Length of cables > 200 km
PoP
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
XPDR
PoP
PoP
PoP : Point-of-Presence
Submarine Cable
Suggested configuration can provide huge cost savings especially for high-capacity transmission systems
E.g. up to 45% cost reduction for 6Tbit/s (60 x 100G) transmission system
Example : Submarine transport system with
regeneration at intermediate land site.
© 2014 Xtera Communications, Inc. Proprietary & Confidential 47
• Signals: 8 x 120 Gbit/s (1558.2 nm to 1563.9 nm)
• Span configuration: – Total 646.4 km, 120.5 dB, +11,374 ps/nm
– SMF 303.5 km, 59.7 dB (+5,024 ps/nm )
– PSCF 342.9 km, 60.8 dB (+6,340 ps/nm)
• Bi-directional transmission – Direction A: SMF Span PSCF Span, Pre-DCU: -540 ps/nm
– Direction B: PSCF Span SMF Span, Pre-DCU: -650 ps/nm
• ASE suppression filter is used to remove ASE accumulation from the first span.
Experimental Setup for 8 x 100G Transmission Over Two Spans With Total Loss of 120.5 dB
FWD Pumps
BKWD Pumps
DFB
DFB
DFB
100G MXP
100G Comb
DCM PM
MU
X
EOA EOA
Filter for ASE suppression
EOA
BKWD Pumps
FWD Pumps
8 x 120 Gbit/s PM-QPSK
8 c
hannels
100 G
Hz
spaci
ng
Direction A) SMF 303.5 km. 59.7 dB Direction B) PSCF 342.9 km. 60.8 dB
Direction A) PSCF 342.9 km. 60.8 dB Direction B) SMF 303.5 km. 59.7 dB
0
5
10
15
20
25
30
35
40
1530 1540 1550 1560 1570 1580
Lo
ss (
dB
)
Wavelength (nm)
ASE Suppression Filter
© 2014 Xtera Communications, Inc. Proprietary & Confidential 48
Numerical Analysis and Measured Spectra – Direction A
Span-1 SMF 303.5 km
Span-2 PSCF 342.9 km
Direction A
The maximum signal power +9.5 dBm at 29.9 km from
the transmit side
The maximum signal power +7.6 dBm at 37.4 km from the start of the 2nd
span
Forward pump 1,170 mW
Forward pump 1,136 mW
Backward pump 1,040 mW
12
14
16
18
20
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
Wavelength (nm)
Direction A: Span-1 Output
10
12
14
16
18
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
OS
NR
(dB
)
Wavelength (nm)
Direction A: Span-2 Output
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
Pow
er
(5dB
/div
)
Wavelength (nm)
Direction A: Input
Backward pump 1,055 mW
© 2014 Xtera Communications, Inc. Proprietary & Confidential 49
12
14
16
18
20
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
Wavelength (nm)
Direction B: Span-2 Output
10
12
14
16
18
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
OS
NR
(d
B)
Wavelength (nm)
Direction B: Span-1 Output
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
Po
we
r (5
dB
/div
)
Wavelength (nm)
Direction B: Input
Span-2 SMF 303.5 km
Span-1 PSCF 342.9 km
Direction B
The maximum signal power +9.8 dBm at 34.1 km from
the transmit side
The maximum signal power +6.4 dBm at 35.1 km from the start of the 2nd
span
Forward pump 1,186 mW
Forward pump 1,132 mW
Backward pump 1,055 mW
Backward pump 1,041 mW
Measured Spectra and Numerical Analysis – Direction B
© 2014 Xtera Communications, Inc. Proprietary & Confidential 50
• Direction A – OSNR: Avg. 18.3 dB (Span-1 Out), 14.7 dB (Span-2 Out)
– Q: Avg. 7.0 dB
– Error free after SD-FEC
• Direction B – OSNR: Avg. 18.2 dB (Span-1 Out), 14.7 dB (Span-2 Out)
– Q: Avg. 6.7 dB
– Error free after SD-FEC
Measured OSNR and Q
6.0
6.4
6.8
7.2
7.6
8.0
8.4
8.8
9.2
9.6
10
11
12
13
14
15
16
17
18
19
1558 1559 1560 1561 1562 1563 1564
Q (
dB
)
OS
NR
(d
B)
Wavelength (nm)
6.0
6.4
6.8
7.2
7.6
8.0
8.4
8.8
9.2
9.6
10
11
12
13
14
15
16
17
18
19
1558 1559 1560 1561 1562 1563 1564
Q (
dB
)
OS
NR
(d
B)
Wavelength (nm)
Span-1 Out:Measured OSNR
Span-1 Out:Simulated OSNR
Span-2 Out:Measured OSNR
Span-2 Out:Simulated OSNR
Span-2 Out:Measured Q
Q threshold ofSD-FEC
Direction A Direction B
© 2014 Xtera Communications, Inc. Proprietary & Confidential 51
Implementation in 100 Gbit/s System
XLA (XLS + ILA)
5 intermediate sites are supported by XLA configuration, which can save more than 300 x 100G transponders over entire network.
© 2014 Xtera Communications, Inc. Proprietary & Confidential 52
150 x 120 Gbit/s Field Trial Over 1,504 km Using All-Distributed Raman Amplification
OFC 2014, Paper Tu2B.2
• All-distributed Raman amplification for coherent signal transmission is introduced.
• 15 Tbit/s (150 x 120 Gbit/s) field trial over 1,504 km with all-distributed Raman amplification
© 2014 Xtera Communications, Inc. Proprietary & Confidential 53
150 x 120 Gbit/s Field Trial Over 1,504 km Using All-Distributed Raman Amplification
Aged network fiber
79.2 km
IL: 20 - 23 dB
45 C-Band
(odd) DFBs
30 L-Band
(odd) DFBs
45 C-Band
(even) DFBs
30 L-Band
(even) DFBs
100G
Comb
100G
Comb
L-100G MXP
C-100G MXP
WSS
x19
C-100G MXP
C-100G MXP
90/10
100 GHz PM-AWG
Wide-band Booster
Backward Raman
Forward Raman
GFF
Optional modules
: PM 3 dB (50/50) coupler : 3 dB (50/50) coupler : 90/10 coupler
L-band De-Mux
C-100G MXP
L-100G MXP
Span # 01 20.3 dB
Span # 02 22.5 dB
Span # 03 22.8 dB
Span # 04 22.2 dB
Span # 05 21.5 dB
Span # 06 20.4 dB
Span # 07 22.6 dB
Span # 08 20.1 dB
Span # 09 21.4 dB
Span # 11 22.9 dB
Span # 12 20.5 dB
Span # 13 21.3 dB
Span # 14 22.1 dB
Span # 15 21.8 dB
Span # 16 23.1 dB
Span # 10 21.6 dB
Span # 17 22.2 dB
Span # 18 22.4 dB
Span # 19 22.1 dB
19 x 7 x
Backward Raman pump module
GFF Type I 5 x GFF Type II 5 x
Forward Raman pump module
Total distance: 1,504 km (19 spans)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 54
• All-distributed Raman amplification makes the span output signal power higher than the input signal power.
– Signal power rises sharply at the end of the span caused by strong backward
Raman pumping.
– Average signal input power: -6.0 dBm/channel
– Average signal output power: -4.3 dBm/channel
Simulated Per Channel Power Profiles Over Distance
• Steep rise at Rx side • Lower input power to the next
span due to the insertion loss of Raman pump modules and GFFs
Power profile with forward Raman pump
© 2014 Xtera Communications, Inc. Proprietary & Confidential 55
• OSNR: Average = 19.6 dB
• Q (dB): Average = 11.4 dB, Min = 11.2 dB (Threshold = 6.4 dB)
Transmission Results: Measured OSNR and Q Factor (150 x 100G Over 19 Spans – 1,504 km)
Wavelength (nm)
1530 1540 1550 1560 1570 1580 1590 10
12
14
16
18
20
22
11.0
11.5
12.0
12.5
13.0
13.5
14.0
Q facto
r befo
re S
D-F
EC
(dB
)
OS
NR
(dB
/ 0
.1nm
)
© 2014 Xtera Communications, Inc. Proprietary & Confidential 56
• Unrepeatered transmission systems provide cost effective solution for – Communication between islands or main-lands
– Communication for oil platforms (for oil and gas company)
– Skipping intermediate sites in hostile areas (tropical forest, desert...)
• Key technologies for unrepeatered transmission – Distributed Raman amplification
– ROPAs, high-order pumping
• Current 100G unrepeatered transmission system can support – Up to 557 km (90.2 dB) distance
– 15 Tbit/s transmission over 389 km G.652 fiber (5.84 Pbit/s km)
• Application in “repeatered” system – Transmission over cascaded “very long” spans
– Improving performance over difficult spans in terrestrial network
Summary
100G + Raman Powering Submarine and
Terrestrial Networks
“15 Tb/s Unrepeatered Transmission Over 409.6 km Using Distributed Raman Amplification and ROPA“ ACP 2014 Post-Deadline Paper AF4B.4
Thanks
Any Questions ?