2015 09 09-unrepeatered-systems-presentation-snw-singapore-2015

© 2015 Xtera Communications, Inc. Proprietary & Confidential 1

Unrepeatered Systems:Farther, Faster Over a Single Span

9 September 2015

Philippe A. Perrier


Innovative Unrepeatered Offering Confidential – Xtera Communications, Inc. Proprietary

Example of Driver for Longer Single-Span Systems

PoPCable Landing StationSubmarine cableTerrestrial extension

City A

City B



Example of Driver for Longer Single-Span Systems (Cont’d)

City A

City B

BMH

BMH

PoP

Submarine cableTerrestrial extension

• Because unrepeatered systems are loss-limited, there is a direct link between capacity and reach performance


1. Fiber:– Lower attenuation fiber is always better Ultra low-loss (G.652B, G.654B)

– Type Fibers with large effective area tolerant to higher launched power

2. Line rateModulation formatPulse shapingChannel densityWavelength of transmission (fiber attenuation lower in L-band)Detection (direct / coherent) Forward Error Correction (Hard-Decision FEC / Soft-Decision FEC)

3. Power management– Launched power; power in the line fiber

– Non-linearities mitigation

Maximizing Reach in Single-Span SystemsTool Kit


4. Raman amplification– Results from the interaction of an optical radiation (“pump”) with molecular

vibrations of the glass

• Maximum gain at a shift of ~ 100 nm in the 1550 nm window

– In any fiber types

– The more pump power the more gain

– Raman gain improves with lower

fiber attenuation (larger Leff)

Thus the NF and OSNR improvements

due to Raman will be larger in lower

attenuation fiber at the same

Raman pump power.

Maximizing Reach in Single Span SystemsTool Kit (Cont’d)

0

1

3

4

5

6

6 12 18 24 30 36 42

2

048

Frequency shift (THz)

Ram

an g

ain

(a.u

.)

PumpResulting gain

~ 100 nm


Raman AmplificationPower Profile along the Span (Backward Raman)

266 km (61.2 dB); G.652D

Gain from backwardRaman pumping

Fiber attenuation

15x100G


Raman Amplification Power Profile along the Span (BWD & FWD Raman)

288 km (65.5 dB); G.652D


Fiber attenuation

15x100G

Gain fromforwardRamanpumping


5. Remote Optically Pumped Amplifier (ROPA)– Passive sub-system, made up of a few optical components (housed in an

enclosure jointed to the cable) and pumped from one end of the span

(typically, receive end)

– Basically, performs the function of a mid-span EDFA

– More pump power allows ROPA to be located further away from the terminals

Maximizing Reach in Single Span SystemsTool Kit (Cont’d)

ROPA

Erbiumdoped

fibreSignalin

Signalout

Optical pump (from the receive terminal)

~ 100 km


ROPAPower Profile along the Span

373 km (76.1 dB); G.652B


Fiber attenuation

15x100G


GainfromROPA

ROPA

107 km


• Corning® Vascade® EX2000 (G.654B), Aeff=112 mm2

• Span loss = 90.2 dB (cable attenuation = 0.162 dB/km)

Unrepeatered 1x100G Transmission over 557kmField Trial with Verizon Business

ROPA

ForwardRamanpumping

BackwardRaman

pumping



Fiber attenuation

Gainfrom

ROPA

Direction oftransmission

291 km 133 km

1 wavelength

ROPA

133 km

GainfromROPA

Pe

r ch

an

ne

l po

we

r (d

Bm

)

Transmission distance (km)

EDFA


• EDFA only at transmit and receive sidesSD-FEC (15%; 6.4 dBQ threshold); target OSNR = 13.5 dB

Contribution of Key Techniques to Transmission Performance – Baseline

340 km (55.5 dB)

Launched power = 14.8dBm

OSNR

Signal

ASE


+56 km / +9 dB with respect to the baseline

Contribution of Backward Raman Amplification

396 km (64.5 dB)

Launched power = 14.8dBm


Extra +63 km / +10.3 dB

Contribution of Forward Raman Amplification

459 km (74.8 dB)

DCM

Launched power = -4.4dBm


Extra +67 km / +10.8 dB

Contribution of Backward ROPA

526 km (85.6 dB)


DCM

ROPA


Extra +31 km / +4.6 dB

Contribution of Forward ROPA


DCM

ROPAROPA

557 km (90.2 dB)


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1525 1535 1545 1555 1565 1575 1585 1595

Po

wer (d

Bm

)

Wavelength (nm)

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0

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1525 1535 1545 1555 1565 1575 1585 1595

Po

wer (d

Bm

)

Wavelength (nm)

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-10

-5

0

5

1525 1535 1545 1555 1565 1575 1585 1595

Po

wer (d

Bm

)

Wavelength (nm)

410 km (68.2 dB), 150 x 100G Unrepeatered Transmission over G.654B Fiber

289 km

ROPA

121 km


Gain from backward

Raman pumping

Fiber attenuation

150 wavelengths

Gainfrom

ROPA

Pe

r ch

an

ne

l po

we

r (d

Bm

)

Transmission distance (km)

LRA (Discrete Raman amplifier) LRA

<Pout> = -2.8 dBm/ch <OSNR> = 14.2 dB



Conclusion

PoPCable Landing StationSubmarine cableTerrestrial cableROPAILA

• Not limited to single-span systems


• Span 1: G.654C fiber; 330 km (59 dB)

• Span 2: G.652D fiber; 300 km (59 dB)

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Pow

er

(dB

m)

Wavelength (nm)

150 x 100G Transmission over Cascade of 2 Unrepeatered Spans (630 km, 118 dB)

ROPA

LRA LRALRA

Span 1

ROPA

Span 2

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1525 1535 1545 1555 1565 1575 1585 1595

Po

we

r (d

Bm

)

Wavelength (nm)

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0

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1525 1535 1545 1555 1565 1575 1585 1595

Po

we

r (d

Bm

)Wavelength (nm)

100 km 110 km

<Q> = 7.0dB



Conclusion

PoPCable Landing StationSubmarine cableTerrestrial cableROPA

• Not limited to single-span systems

• Not limited to submarine space (e.g., terrestrial, DCI)

Maximizing Network Capacity, Reach and ValueOver land, under sea, worldwide


2015 09 09-unrepeatered-systems-presentation-snw-singapore-2015

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