For internal use
Multi-mode SDM systems: upgrade scenario for
legacy systems and achievable system cost
25.09.2013
Maxim Kuschnerov1, Vincent Sleiffer²
1: Coriant R&D GmbH, ModeGap
2: TU Eindhoven, ModeGap
© Coriant © Coriant For internal use
New potential technologies for optical communications
M. Kuschnerov 2
4 x 100G QPSK
150GHz
3000km
5 x 200G 16QAM
200GHz
800km
…
200GHz
1569.59 1568.77 1531.12 1530.33 , nm 1569.18 1568.36 1530.72 1531.52
400G
1T
200G
Sym
bo
ls p
er
bit
40G
100G
25GHz
50GHz 50GHz 87.5GHz
2013
Multi-mode (solid / hollow core)
Multi-core
Orbital angular momentum
Ribbon fiber
2020
Coherent superchannels
© Coriant © Coriant For internal use
What is SDM over multi-mode fibers?
• Transmission of independent
channels over orthogonal modes of
a multi-mode fiber
• Capacity is increased by the number
of modes
• Mode-Xtalk can be compensated
using signal processing
M. Kuschnerov 3
© Coriant © Coriant For internal use
Advantages vs. other SDM technologies › Highest possible integration
› Lowest overall system costs (integrated amplifiers and ROADMs)
› Easier handling/splicing
› Lowest nonlinearity (hollow-core)
› Lowest achievable latency (hollow-core)
› Lowest potential loss (hollow-core)
› Higher bandwidth (hollow-core)
Why multi-mode technology?
M. Kuschnerov 4
© Coriant © Coriant For internal use
Technologies developed within the project
• Integrated mode-mux / dmux
› Photonic Integrated Mode Coupler 3D waveguide
• Prototypes presented for 3 modes
• Design is scalable beyond 3 modes
M. Kuschnerov 5
© Coriant © Coriant For internal use
Technologies developed within the project
• Multi-mode amplifier
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LP01 LP11a LP11b
-30 -20 -10 0 10 20 30-0.002
0.000
0.002
0.004
Core [m]
FRIP
LP01
LP11
Phase plate
DM
(HR=980, HT=1550nm)
DM
Pump LD
(=980nm)
SMF
signal
Pump
(Breadboard dimension=30x45cm)
TMF
TMF
1530 1540 1550 15600
5
10
15
20
25
Gai
n [d
B]
Wavelength [nm]
19.5dBm: LP01, LP11a, LP11b
22.0dBm: LP01, LP11a, LP11b
25.2dBm: LP01, LP11a, LP11b
Pp:
© Coriant © Coriant For internal use
Technologies developed within the project
• Solid core multi-mode fiber (3 & 6 modes) Hollow core multi-mode fiber
• All Tx / Rx components @ 2µm
• Thulium doped fiber amplifiers @2µm
• Scalable digital signal processing for SDM
M. Kuschnerov 7
© Coriant © Coriant For internal use
Records set in Modegap
• 57.6Tb/s record capacity over solid-core multi-mode fiber 1
• 57.6Tb/s record capacity over hollow-core photonic bandgap fiber ²
• First higher-order modulation transmission over multi-mode fiber (solid & hollow) 1&2
• First coherent transmission over hollow core fiber ²
• Highest reach (>1,000km) over multi-mode fibers with inline multi-mode amplifiers
1 V.A.J.M. Sleiffer et al., “73.7 Tb/s (96X3x256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA”,
ECOC 2012 postdeadline.
² Y. Jung et al., “First Demonstration of a Broadband 37-cell Hollow Core Photonic Bandgap Fiber and Its Application to High
Capacity Mode Division Multiplexing”, OFC 2013 postdeadline
M. Kuschnerov 8
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Customer view on Space Division Multiplexing #1
• The customers want to stay with the installed fiber base as long as possible › Installed fiber base is often ~20 years old with no upgrades done in a long time
› 400Gb/s the middle term solution for more spectral efficiency (2016+) target metro
› C+L band afterwards (esp. customers who lease fiber)
› Verizon costs for US network upgrade: $1B
• Sufficient installed capacity › No urgent need of capacity: “we still can provide enough capacity for the near future / till 2020”
› Important to distinguish between operators who own or lease fiber
• There’s a fear of new technology › Many carriers had problems in the field with a new SMF fiber types not even advanced SMF fibers will be
deployed until they are fully tested and understood
› Some carriers claim to never deploy multi-mode fiber under current management
› Every carrier has a long history of new technology failing in the field (basically every component in a
system). Replacing everything at once is not an option
M. Kuschnerov 9
© Coriant © Coriant For internal use
Customer view on Space Division Multiplexing #2
• Look for cheaper alternatives › Fiber bundles with ribbon fiber
› Combine with proven, compatible single mode technology
• Prefer different SDM technology › NTT / Japan is set on multi-core for research, with unclear advantage vs. multi-mode
› Transitional networks prefered that can support fiber ribbons and multi-core fiber
• Consider the correct timeline › AT&T sees SDM needed for 2025
› 400G ramping up in 2016-2018 (400G Ethernet standard not before 4016)
• SDM for political reasons / marketing › Supplier has a few-mode amplifier on the roadmaps without committed timelines
• Too high economic investment › Full eco-system of components needs to be developed (with multiple sources) before a commitment for a
system can be made
M. Kuschnerov 10
© Coriant © Coriant For internal use
Customer view on Space Division Multiplexing #3
• Excitement about the general technology › Customers are very excited about the new technology when they actually see it
› None of the customers in the lab has seen something like this before
› In total, we spent many hours discussing all the technology variants with the customers in a vivid interaction
› Huge excitement for hollow-core technology. Customers didn’t believe it works
• New technology must fulfill certain requirements › Cost / bit must be clearly lower than legacy systems
› Number of channels must stay the same as in current 100G systems
› Gradual upgrade of links should be possible (replace one span by multi-mode)
• Low latency applications › Hollow core loss not acceptable for low latency applications
› No new amplifier huts can be installed
A story is needed based on cost / bit with a smooth upgrade scenario
M. Kuschnerov 11
© Coriant © Coriant For internal use
Gradual system upgrade scenario
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• New transponders, amplifiers and ROADMs are single-mode and multi-mode capable
• Legacy transponders can run over multi-mode equipment without degradation
• N modes are run either on N SSMFs or groomed together on a multi-mode fiber
Backwards compatibility of SDM equipment allows a gradual upgrade scenario
nx mode-1Tb/s
nxROADM Terminal
Terminal
Single-mode
amplifiers
Multi-mode
amplifier
mxROADM
100G
nx-1T
nxSSMF
nxSSMF
nxSSMF
nxSSMF
Multi-mode
fiber
nxSSMF
nxROADM nxROADM
MU
X D
MU
X
© Coriant © Coriant For internal use
Scenario 1: Legacy interoperability of SDM
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• Demonstrated over 1,247km of transmission in a live network (SSMF, TWRS, MMF)
• No additional penalty of multi-mode equipment compared to single-mode transmission
ROADM Terminal
Terminal
Multi-mode
amplifier
ROADM
SSMF
SSMF
Multi-mode
fiber
SSMF
ROADM ROADM
Coriant 100G
© Coriant © Coriant For internal use
Scenario 2: nxSSMF MMF nxSSMF
M. Kuschnerov 14
• Demonstrated over 3 modes in combination with field-deployed SSMF
• 8QAM, 16QAM modulation formats
Terminal
Terminal
Multi-mode
amplifier mxROADM
3xSSMF
nxSSMF
3xSSMF
Multi-mode
fiber
3xSSMF
nxROADM nxROADM
MU
X D
MU
X
3x200G
© Coriant © Coriant For internal use
Scenario 3: Multi-rate, multi-distance, multi-Tx
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• Hybrid transmission demonstrated in interoperation with deployed live network
• Transmission over 1,247km (SSMF, TWC, MMF)
Terminal
Terminal
Multi-mode
amplifier mxROADM
3xSSMF
1xSSMF
3xSSMF
Multi-mode
fiber
3xSSMF
nxROADM nxROADM
MU
X D
MU
X
2x200G
1x100G
© Coriant © Coriant For internal use
System cost modeling
Modeled components: Transponders, regenerators, ROADMs, amplifiers, shelves, fiber,
other
M. Kuschnerov 16
Single mode Multi-mode
Data rate 1Tb/s (QPSK) / 2Tb/s (8QAM / 16QAM)
Subcarriers 10 1 with 10 modes
Optics Int.10 transceiver Int. 10mode transceiver
Max. capacity / fiber (C-band) 50Tb/s 500Tb/s
Mux / Dmux WDM Mode multiplexing
DSP 1 chip with 10 parallel
subcarriers
1 chip with 10 combined
modes
ROADM Standard Single multi-mode ROADM
Amplifier Standard Single multi-mode amplifier
Fiber SSMF / PSCF Solid-core MMF, hollow core
MMF
© Coriant © Coriant For internal use
Longhaul vs. metro-regio
1,000km vs. 3,000km link
• C+L band with Raman amplification
• Longhaul: 7 spans / node
• Metro-regio: 2 spans / node
• 20K€ / km fiber deployment costs
• 30% mark up for multi-mode if similar
technology
M. Kuschnerov 17
© Coriant © Coriant For internal use
Total cost @ 1Pb/s
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1,000km metro-regio link 3,000km longhaul link
© Coriant © Coriant For internal use
Variation of fiber deployment costs
• Fiber deployment costs are
network / country dependent
• Options:
Aerial
Blowing in existing tubes
Digging for new trenches
• Verizon estimate (OFC 2013):
$18K-$30K
• Other estimates range from:
$15K-$300K
M. Kuschnerov 19
© Coriant © Coriant For internal use
Owned vs. leased fiber
• Deployment costs depend on
whether the operator owns the fiber
plants
• Cost analysis without taking into
account fiber costs (assuming a
lease is already running)
M. Kuschnerov 20
© Coriant © Coriant For internal use
Next steps
• Development of missing technologies › Isolators, circulators, gain flattening filters, all-mode couplers/splitters, mode converters, VOA, tunable
filters,
› Spatial wavelength selective switch
• Scaling of existing technologies › 10-mode multi-mode fiber with low DGD, low PDL
› Multi-stage 10-mode amplifiers with automated controls and longhaul performance
› 10-mode multiplexers
› Investigating the potentially lower nonlinearity of solid core multi-mode fibers
• Pushing cutting edge hollow core fiber development › Loss reduction
› Manufacturability
M. Kuschnerov 21
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