Fiber Technology Trends for Next Generation Networks

Christopher Towery
Corning Optical Communications
May 28th 2015
towerycr@corning.com
IV Towards Terabit per Second Optical
Networking
International Workshop on Trends in
Optical Technologies

Optical Fiber 2
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© 2015 Corning Incorporated .
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Outline
• Hero Experiments and Technology Trends
• Quasi-Single Mode Fibers
• Submarine Network Evolution
• Un-repeatered and long span terrestrial applications
– Extending the network through challenging terrain
• Extending systems reach in a legacy network

Optical Fiber 3
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Capacity-distance reach shows signs of consistent growth,
however, no new records were set (534 Pb/s x km is still max.)
SDM = Multi-core fibers + Few-mode fibers
OFC 2015

Optical Fiber 4
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No records observed in total capacity either in SMF or SDM
(FMF and MCF) fibers
• Appetite for hero SDM transmission experiments seems to be fading (see
red points)…
• …But there was an increased number of results related to components
and fiber designs to enable SDM transmission (not reflected in the graph)
OFC 2015

Optical Fiber 5
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What are the CDN’s saying about submarine networks?
-- More capacity…..

Optical Fiber 6
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CDNs could be very large, their backbone is global, resembles
submarine network with “long, big pipes”
~10,000 km
~5,000 km
~5,000 km
V. Kamalov et. al. ECOC 2014

Optical Fiber 7
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Using more modes to get higher capacity
2 related approaches
7
• Few-mode fibers are considered for mode-multiplexed transmission with
MIMO receivers
• Requires major transformation of the optical communication infrastructure
• Benefits of the parallelism brought by MDM is not well established
• Signal processing complexity is significant, and scales with transmission distance
[1] F. Yaman et al., Opt. Express, 18, 21342-21349 (2010).
[2] J. D. Downie et al, Opt. Express, 19, B363-B369 (2011).
[3] Q. Sui et al, Opt. Express, 23, 3156-3169 (2015).
• Few-mode fibers can be used for Quasi-single mode (QSM) transmission:
• FMFs can be used for the benefit of their larger effective area.
• FMFs can be incorporated into the existing single-mode infrastructure if signal is transmitted only in the
fundamental mode.
• QSM suffers from multi-path interference (MPI). However, MPI can be mitigated with DSP.

Optical Fiber 8
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• In traditional single-mode fibers the light propagates in the fundamental
mode, which is the only mode supported in the fiber
• In quasi-single mode fibers, the light is “forced” on a fundamental mode
Tx Rx
Tx Rx
How does a Quasi-Single Mode Fiber work?

Optical Fiber 9
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Quasi-single mode transmission with hybrid spans
9
FMF
Splice Splice
SM-EDFA SM-EDFA
Low DMA
High DMA
Single-mode fiber
[1] F. Yaman et al., Proc. OFC’13, paper OTu1D.2 (2012).
[2] Q. Sui et al, Opt. Express, 23, 3156-3169 (2015).
[2]
Power
Span Length
Splice
MPI
Span Length
[1]
DMA:= Differential modal attenuation

Optical Fiber 10
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Technology – Ultra-Large Aeff
OFC 2015 post-deadline paper demonstrates record SE over
Trans-Atlantic distance using Quasi-SMF fiber

Optical Fiber 11
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Hybrid Spans
11
Fiber Length (km) Atten (dB/km) Loss (dB)
Span1 102.82 16.5
FMF 51.15 0.154
Vascade®
EX3000
51.67 0.149
Span2 101.75 17
FMF 51.4 0.16
EX3000 50.35 0.157
Span3 100.01 16
FMF 51.4 0.156
EX3000 48.61 0.156
Span4 102.17 16.7
FMF 51.15 0.16
EX3000 51.02 0.154
Span5 101.43 16.2
FMF 51.4 0.156
EX3000 50.03 0.153
x5
FMF Vascade®
EX3000Bridge Fiber
Parameters FMF Vascade®
EX3000
Effective
Area
~200 µm2 150 µm2
Supported
Modes
LP01, LP11
Diff. Modal
Attenuation
0.3-0.5 dB/km
Diff. Modal
Group Delay
~0.93 ns/km
• Vascade® EX3000 is used as bridge fiber between FMF
and amplifier pigtail.
• Tapered splicing is used between all splice points
between dissimilar fibers
• Average loss from the total of 4 splices and two
connectors are 0.7 dB.

Optical Fiber 12
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-20 -15 -10 -5 0 5 10 15 20
-35
-30
-25
-20
-15
-10
-5
0
Time (ns)
|H11
|2
(dB)
All-single-mode fiber
All-few-mode fiber
Hybrid
All-SMF vs ALL-FMF vs Hybrid spans
Hybrid has
less MPI
All-Single-Mode Fiber Loop All-Few-Mode Fiber Loop Hybrid span Loop
16 17 18 19 20 21 22 23 24 25 26 27
2
3
4
5
6
7
8
9
Received OSNR @ 0.1 nm (dB)
Q(dB)
4060 km
All-single-mode-fiber
16 17 18 19 20 21 22 23 24 25 26 27
2
3
4
5
6
7
8
9
Q(dB)
4060 km
All-few-mode fiber
1 dBMPI
16 17 18 19 20 21 22 23 24 25 26 27
2
3
4
5
6
7
8
9
Q(dB)
4060 km
All-few-mode fiber
Hybrid
16 17 18 19 20 21 22 23 24 25 26 27
2
3
4
5
6
7
8
9
Q(dB)
4060 km
2030 km
All-few-mode fiber
Hybrid
MPI_FMF -10.88 dB
MPI_Hybrid -14.69 dB

Optical Fiber 13
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Paths to higher submarine cable capacity
Paths to Higher Capacity
More λ’s in C
band
C+L band
EDFA
Use >8 FPs in
the repeater
Vascade
EX2000
Vascade
EX3000
50
km
80
km
50
km
80
km
80 λ’s 15.5 17.1 16.3 17.9
100 λ’s 16.5 18.1 17.3 18.9
150 λ’s 18.2 19.8 19 20.6
• Only small additional
power is needed (rel.
to current 17-19 dBm)
• No change in design
• Possible to support
300 λs for C+L band
transmission
• May require re-
designed repeaters
• May need more/re-
design power feed
equipment
• Use of all 8 FPs is
supported by an
original design
• No change in design
Use all 8 FPs in
the repeater
• May require more
repeaters or re-
designed repeaters
• Requires more
copper to reduce
resistance; more
expensive cable
Will likely be developed in parallel

Optical Fiber 14
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Challenge
Objective
Expanding Terrestrial Backbone Networks
Two scenarios operators are facing today
Greenfield
Building fiber
where it isn’t
available today
Difficult
environments
Legacy
Meeting
increased
demand
Aging
infrastructure
Cost (CapEx, OpEx), Reliability, Speed to Rollout,
Complexity,…..

Optical Fiber 15
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The carriers that are building greenfield long haul networks are
doing so for various reasons
Routing Diversity
Access to new
markets
Support for national
broadband plans
Backhaul for wireless
build-outs

Optical Fiber 16
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Greenfield long haul builds are also often driven by non-telco
operators, a few examples
DefenseOil and Gas
Science Border SecurityElectric Utilities

Optical Fiber 17
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Many of the new long haul builds are going through
challenging terrain

Optical Fiber 18
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Locating and powering remote amplifier or repeater sites can
be problematic
Sites require power for equipment
and cooling
Many may not even be accessible
365days a year

Optical Fiber 19
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How much can an intermediate amplifier site cost?
Amplifier Site Requirement Estimated Costs (low) Estimated Costs (high)
Site construction costs
(acquisition, preparations,
security, etc.)
$100k $250k+
Controlled Environment Vault
(CEV)
$30k $150k
AC Power Construction
($22k/km)
$10k $500k
DC Power Back-up (Batteries,
Fuel Cells, Generator, etc.)
$150k $300k
OPEX ( Fuel, Service, Labor,
Road Access, Site
Maintenance, Security etc.)
$36k/year $200k/year
Total of first year costs $326k $1.4M
Additionally, reliability and accessibility can be issues in some regions

Optical Fiber 20
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Minimizing intermediate amplifier or regenerator sites can be a
key consideration
Example: China’s State Grid Project
through the Himalayas
• Average Elevation 5,000m,
temperatures as low as -55C
• Span distances > 300km
One very long span Or several long spans
Example: TIM Brasil through Amazon
region
• Over 2000km of OPGW
• 13 Spans longer 100km, 5 Spans
longer than 200km

Optical Fiber 21
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Technologies are enabling more robust and flexible network
design, and reducing the need for intermediate amplifier sites
Better Electronics
Modulation and FEC
Increase in optical link length
adopting next generation FEC
1st gen
FEC
2nd gen
FEC
2nd gen
FEC
3rd gen
FEC
3rd gen
FEC
4th? gen
FEC
Coherent Detection
Advanced Amplification
EDFA
High Power EDFA
+ Counter Propagating Raman
+ Co-Propagating Raman
+ ROPA
+ Dual ROPA
Ultra Low Attenuation
and Large Aeff Fibers
“Low-Loss”
“Ultra-Low-Loss”
“Ultra-Low-Loss”
+
Large Aeff

Optical Fiber 22
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.15 0.155 0.16 0.165 0.17 0.175 0.18
CummulativeProbablity(%)
Attenuation at 1550 nm (dB/km)
Cable
Fiber
Post dead-line paper at OFC 2014 makes use of
coherent detection, Raman amplification and
advanced fiber to set new 100G distance record
• Cable: 8.3 km Altos loose tube 204 cable on a 0.9m diameter spool
• Optical Fiber: Vascade EX2000 with Aeff=112 µm2
– Median attenuation improved after cabling from 0.161 dB/km to
0.159 dB/km, max attenuation 0.173 dB/km
• Span: 556.7 km, total loss 90.2 dB, spliced attenuation 0.162 dB/km
Source: Xia, Chang, Ten, et al OFC 2014 Th5A.7

Optical Fiber 23
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Trial set-up: Utilized Dual Raman and ROPA
100G MXP λ1
100G MXP λ2
100G MXP λ3
100G MXP λ4
WSS
DCU
EOA 289.3 km
or
255.8 kmROPA (F)
133.7 km
EOA
ROPA (B)
Residual
pump
sharing
WSS
Forward
Raman
Backward
Raman
100G MXP λ1
100G MXP λ2
100G MXP λ3
100G MXP λ4
(a)
ROPA (B)
ROPA (F)
p
P’
133.7 km
556.7 km for 1 x 100G transmission and 523 km for 4 x 100G transmission
Passive repeater
Source: Xia, Chang, Ten, et al OFC 2014 Th5A.7
Vascade®
EX2000 fiber

Optical Fiber 24
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We have demonstrated two record results at OFC 2015 with
two external partners: ASN and Xtera

Optical Fiber 25
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Challenge
Objective
Expanding Backbone Networks
Two scenarios operators are facing today
Greenfield
Building fiber
where it isn’t
available today
Difficult
environments
Legacy
Meeting
increased
demand
Aging
infrastructure
Cost (CapEx, OpEx), Reliability, Speed to Rollout,
Complexity,…..

Optical Fiber 26
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We have recently investigated maximum reach and achievable
capacity over a DT network when using three types of fibers
• Transparent network
(no intermediate
regeneration)
• 504km is the maximum
distance between two
adjacent cities

Optical Fiber 27
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Fiber rankings in terms of transmission reach:
1) Vascade® EX2000; 2) SMF-28® ULL; 3) Legacy fiber
• System parameters:
– EDFA noise figure: 5dB
– Span length: 80km
– WDM channels: 150
– Cable drum length: 4km
– Splice loss: 0.05 dB
– 32Gbaud (6.25dB FEC threshold)
– Polarization multiplexing
– End-of-life cable margin: 3dB/100km
– Additional Q margin: 3dB
Legacy fiber Corning®
SMF-28® ULL
Corning®
Vascade® EX2000
Attenuation
(dB/km)
0.25 0.165 0.159
Aeff (µm2) 82 82 112
n2 (m2/W) 2.3 x 10-20 2.1 x 10-20 2.1 x 10-20
Dispersion
(ps/nm/km)
17 17 20.3
Gaussian noise analytical model; implementation penalty neglected

Optical Fiber 28
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Legacy fiber Extra reach enabled by SMF-28 ULL
fiber
Legacy fiber can support 24% of routes at 200G
SMF-28 ULL covers 96% of routes; Vascade EX2000 covers all
Transparent networks make the distribution of distances wider –
SMF-28 ULL fiber covers 96% of links at 200G with 80km spans
Extra reach
enabled by
Vascade EX2000
fiber

Optical Fiber 29
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Building cost effectively as a large incumbent
carrier – Things to think about
Take advantage of existing duct
Take advantage of lower-cost
installation techniques
Convergence
Build as a Consortium

Optical Fiber 31
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• In traditional single-mode fibers the light propagates in the fundamental
mode, which is the only mode supported in the fiber
• In quasi-single mode fibers, the light is “forced” on a fundamental mode
Tx Rx
Tx Rx
How does a Quasi-Single Mode Fiber work?

Optical Fiber 32
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Roadmap for terrestrial system capacity growth:
Smarter Networking, FEC and more Raman
2015 20252020
Raman Amplifiers
100G
MSA
50/100/150/
200G
50-200G; with
finer tuning
FEC Improvements
Smart Networking
The carriers are split on those who deploy 100G now, or wait until
adaptive-rate transponders become available
SE
Reach(km)
50G
100G
200G
3 6
150G
1.5 4.5
SE
Reach(km)
50G
100G
200G
3 6
150G
1.5 4.5

Optical Fiber 33
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WW Long-Haul Market
90% of the New Long Haul Routes are being build outside
North America and Europe
Source: CRU
~90% of the
LH market is
in emerging
regions

Optical Fiber 34
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In 2009 traditional Telecoms started loosing their dominance
as primary carriers of Internet traffic, CDNs gained share
• CDNs became as influential as traditional carriers as telecom
equipment buyers and defining technology direction
2009 University of Minnesota Atlas Observatory study

Optical Fiber 35
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Adaptive modulation techniques optimize today’s wireless
networks and tomorrow’s fiber networks
The same concept is now being used in transmission
over optical fiber – providing similar benefits
Speed (Mb/s)
Distance from cell tower (km)

Optical Fiber 36
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Variable-rate transponder uses adaptive modulation to enable
elastic optical networks
Source: “Extending software defined network
principles to include optical transport”, Verizon,
IEEE Communications Magazine, March 2013
• 1 bit per symbol
• 2 bits per symbol
IncreasingSEandrequiredOSNR
BPSK
QPSK
8 QAM
16 QAM
cHigher modulation density
provides more bits per channel…
…but shortens the reach

Optical Fiber 37
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SMF-28® ULL and Vascade® EX2000 fibers also maximize achievable
capacity for a given reach
QPSK 8-QAM 16-QAMPM-BPSK 32-QAM 64-QAM
Spectral efficiency,
b/s/Hz
Maximum reach,
km
Legacy fiber
SMF-28® ULL fiber
50G
Modulation:
Bit-rate: 100G 150G 200G 250G 300G
50% Vascade® EX2000 fiber
100%
Extra 50%
3x
30%

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