At a time when new network topologies are developed due to the advent of new operators or users of long-haul optical transmission infrastructure, longer spans and longer all-optical data paths are becoming critical capabilities. This presentation details how advanced optical Raman amplification enables these new network designs and ultra-long-haul transmission of 16QAM/200G carriers as well. This presentation was delivered at WDM & Next Generation Optical Networking EMEA 2015 conference (22-25 June 2015 – Nice, France).

1. © 2015 Xtera Communications, Inc. Proprietary & Confidential 1
Super Optical Layer Enabled by
16QAM and Raman Technologies
Bertrand Clesca – Head of Global Marketing – Xtera Communications
23 June 2015
Next Generation Optical Networking 2015 (22-25 June 2015 – Nice, France)

2. © 2015 Xtera Communications, Inc. Proprietary & Confidential 2
Content:
• Why Long Spans Matter
• Recent Technical Improvements
Enabling Longer Span (and Reach)
• Example of Implementation
• Raman Amplification, Key Enabler for 16QAM

3. © 2015 Xtera Communications, Inc. Proprietary & Confidential 3
Why Long Spans Matter

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• Very meshy network with a lot of traffic locations
• Fibers owned, plenty of dark fibers available
Traditional Telecom Network

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• Very sparse network with very few traffic locations  long reach
• Fiber leased, but large pipes needed between few sites
• Technical/commercial benefits from site skipping  long spans
Data Center Operator Network

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• Technical + commercial innovations
• Instead of having back-to-back terminal equipment in red sites, long
span capabilities enable to deploy optical line amplifiers in red sites or to
skip some of these red sites.
Backhaul Networks for Subsea Cable Systems
London
Dublin

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• Network made of leased fibers with few traffic locations
• Sparse population distribution and power availability issues  long spans
Emerging Region Network

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• Optical networks built over power grids
• By design, the fiber is routed to the foot of the transmission tower at
very few locations  long spans
OPGW Network

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• Example in Papua New Guinea: Long spans imposed by the location of
the liquid gas fields and plants
• Valid also for off-shore (and onshore in Middle East) oil rigs
Oil & Gas Industry’s Network
Hides Gas
Conditioning
Plant
Kopi Scraper
266 km
Port Moresby
436 km
LNG plant

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• New types of telecom networks with very few traffic locations
– New players
– DC/PoP-to-DC/PoP network with subsea piece in the middle
• Deserts, mountains, rain forest or tundra are all examples of areas
where intermediate amplifier sites can be prohibitively expensive to
build, power, maintain and keep secure.
– Telecom networks in emerging countries with sparse populations distribution
and power availability issues
– Optical networks built over power grids
– Oil & gas industry
Why Long Spans Matter?

11. © 2015 Xtera Communications, Inc. Proprietary & Confidential 11
Recent Technical Improvements
Enabling Longer Span (and Reach)

12. © 2015 Xtera Communications, Inc. Proprietary & Confidential 12
Optical Transmission Over Long Span
Too High Power: Nonlinear Limitation

Input eye diagram
(NRZ signal)
Output eye diagram
Distance
Perchannelpowerprofile
Nonlinear limitation
Amplifier
power boost
Fiber
attenuation
Pulse
compression
(or distorsion)

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Optical Transmission Over Long Span
Too Low Power: Noise Limitation

Optical
amplifier noise
Input eye diagram
(NRZ signal)
Output eye diagram
Distance
Perchannelpowerprofile
Amplifier
power boost
Fiber
attenuation
Noise limitation

14. © 2015 Xtera Communications, Inc. Proprietary & Confidential 14
Optical Transmission Over Long Span
Limitations on Both Sides

Input eye diagram
(NRZ signal)
Output eye diagram
Perchannelpowerprofile
Nonlinear limitation
Amplifier
power boost
Noise limitation
Fiber
attenuation
Pulse
compression
(or distorsion)
Optical
amplifier noise
Distance

15. © 2015 Xtera Communications, Inc. Proprietary & Confidential 15

Optical Transmission Over Long Span
Raman Enabler: Line Fiber Becomes An Amplifier
Distance
Perchannelpowerprofile
Fiber
attenuation
Backward gain
Forward gain
Backward
Raman
pumping
Forward
Raman
pumping
Adequate eye
opening for proper
signal detection
Input eye diagram
(NRZ signal)
Output eye diagram

16. © 2015 Xtera Communications, Inc. Proprietary & Confidential 16
[Capacity – Reach] in Unrepeatered Links

17. © 2015 Xtera Communications, Inc. Proprietary & Confidential 17
Raman-Assisted Transmission
For Multi-Span Transport
Distance
Perchannelpowerprofile
Lower limit: Optical noise accumulation
Upper limit: Nonlinear distortions
High
peak-to-
peak
power
excursion
EDFA chain
A B C D E F
Power
boost
Fiber
attenuation
Much less
breathing
Higher noise performance
Raman chain
Lower non-linearity
A
Backward Raman pumping Forward Raman pumping
Fiber attenuation
Distributed Raman
gain
B C D E F
Discrete
amplifier

18. © 2015 Xtera Communications, Inc. Proprietary & Confidential 18
Raman-Assisted Transmission
For Multi-Span Transport – All-Distributed Raman
Distance
Perchannelpowerprofile
Lower limit: Optical noise accumulation
Upper limit: Nonlinear distortions
High
peak-to-
peak
power
excursion
EDFA chain
A B C D E F
Power
boost
Fiber
attenuation
Further less
breathing
Higher noise performance
All-distributed Raman chain
Lower non-linearity
A D
Backward Raman pumping Forward Raman pumping
Distributed Raman
gain
Fiber
attenuation
B C E F
Loss due to Raman amplifier
insertion loss

19. © 2015 Xtera Communications, Inc. Proprietary & Confidential 19
Example of Implementation

20. © 2015 Xtera Communications, Inc. Proprietary & Confidential 20
Power Grids
Infrastructure Suitable for Optical Networks
• OPGW cable between
transmission towers
• Not a telco network:
– Long distances
between intermediate
ODF sites

21. © 2015 Xtera Communications, Inc. Proprietary & Confidential 21
Power Grids
Infrastructure Suitable for Optical Networks
• OPGW cable between
transmission towers
• Not a telco network:
– Long distances
between intermediate
ODF sites
– Telecom sites maybe
off the power grid

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Power Grids
Infrastructure Suitable for Optical Networks
• OPGW cable between
transmission towers
• Not a telco network:
– Long distances
between intermediate
ODF sites
– Telecom sites maybe
off the power grid
 Very long spans

23. © 2015 Xtera Communications, Inc. Proprietary & Confidential 23
TIM Brasil
Long Links with Ultra-Long Spans on OPGW Cables
1,161 km
link
Amazonas Project: 2,266 km network
(1,835 km OPGW cable
infrastructure)
Manaus
Gopa
Macapá
Belem
Jurupari
Fortaleza
Salvador
Tucuruí
Puerto Velho
Cuiabá
1,010 km
link
1,645 km
link
TIM Brasil
Long Links with Ultra-Long Spans on OPGW Cables

24. © 2015 Xtera Communications, Inc. Proprietary & Confidential 24
Ultra-Long Spans in 2,266 km Amazon Network
(Highest Span Loss: 63 dB)
ROADM
43 km
13.9 dB
237 km
53.8 dB
278 km
63.1 dB
ILAILA ROADM
142 km
34.6 dB
ILA
138 km
33.1 dB
235 km
53.5 dB
ILA
Villa
Camburão
ROADM
183 km
46.1 dB
141 km
33.9 dB
157 km
37.2 dB
ILAILA ILA
91 km
23.8 dB
ILA
229 km
52.8 dB
ROADM
239 km
54.2 dB
110 km
27.2 dB
ROADM
ILA ILA
43 km
13.9 dB
Manaus
TIM
Terra SantaManaus
Rod Lexuga
Silves Oriximiná
Macapá
TIM
Jurupari
Macapá Sub Laranjal do Jari
Gopa XinguTucuruí Pacaja Vitória do Xingu
Core
amplifier
Backward span
extension module
Forward span
extension module
G.652
fiber span

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• Wise RamanTM solution backed by:
– An unrivalled 17 years of tremendous and unique R&D experience
– An unparalleled 11 years of commercial deployments worldwide
• Wise RamanTM solution covers all the aspects of optical networks relying
on Raman amplification:
– Modeling
– Photonics
– Link engineering
– Network design
– Hardware
– Firmware
– Software
– Network management
 Not simply the addition of third-party
Raman pump modules to EDFA amplifiers
that were designed for stand-alone usage!
Wise RamanTM By Xtera
Raman amplifier controller is key, and
quite different from EDFA controller.

26. © 2015 Xtera Communications, Inc. Proprietary & Confidential 26
Raman Amplification,
Key Enabler for 16QAM

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100/200/400G Implementations
Polarization Multiplexing
(PM)
Multi-level modulation
format
25 Gbaud opto-
electronics
Dual-carrier
implementation
N-level modulation format + Coherent detection + Digital signal processing
25 Gbaud 200 Gbit/s100 Gbit/s
16QAM
200G
PM-16QAM
I
Q
1011
1010
1101
1111
1001
1000
1100
1110
0010
0000
0100
0101
0011
0001
0110
0111
25 Gbaud 100 Gbit/s50 Gbit/s
QPSK100G
PM-QPSK
00
I
Q
10
1101
l
400 Gbit/s
25 Gbaud 200 Gbit/s100 Gbit/s
16QAM
400G
DC-PM-16QAM
I
Q
1011
1010
1101
1111
1001
1000
1100
1110
0010
0000
0100
0101
0011
0001
0110
0111
≈ 50 GHz
(or narrower)

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• Higher OSNR requirement
• Higher sensitivity on fiber nonlinearities
 Practical reach in real network environment with EDFA-based
equipment: 600 km.
• 400G or 1T channels are made, today, on the combination of
2 or 5 x 200G PM-16QAM carriers.
• Higher-end line equipment is required to extend the optical reach
of PM-16QAM carriers.
16QAM Challenges
25 Gbaud 200 Gbit/s100 Gbit/s
16QAM
200G
PM-16QAM
I
Q
1011
1010
1101
1111
1001
1000
1100
1110
0010
0000
0100
0101
0011
0001
0110
0111

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[Capacity – Reach] Metric Enabled by
Xtera’s Wise RamanTM in Terrestrial Networks
240 x 100G
• 100 nm spectrum
• PM-QPSK 100G carriers with
50 GHz channel spacing
• 2 bit/s/Hz spectral efficiency
120 x 400G
• 100 nm spectrum
• PM-16QAM 200G carriers
spaced 50 GHz apart
• 4 bit/s/Hz spectral efficiency
160 x 400G
• 100 nm spectrum
• PM-16QAM 200G carriers
spaced 37.5 GHz apart
• 5.3 bit/s/Hz spectral efficiency
 16QAM on more than 2,000 km of aged terrestrial fiber (0.28 dB/km)

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[Capacity – Reach] Metric Enabled by
Xtera’s Wise RamanTM in Terrestrial Networks

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Innovative Supplier
Of Long-Haul Optical
Transmission
Infrastructure
Aerial
Terrestrial
Submarine