Fibers for mode multiplexing
Lars Grüner-Nielsen
OFS Denmark
Acknowledgements
OFS, Norcross, GA
Yi Sun, Robert Lingle Jr, David Peckham, and Allan McCurdy
OFS Laboratories, Somerset, Nj
Jeffrey W. Nicholson
OFS Denmark
Rasmus Jensen, Dan Jakobsen, Kim Jespersen, and Bera Pálsdóttir
Collaborators in ModeGap project
Collaborators
AlcatelLucent Partner™
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Outline• Requirements• Examples made fibers• Fiber characterization

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Requirements few mode fiber for mode divisionmultiplexing

Property

RequirementDifferential modedelayLow

Systems with MIMO

Not so important

Systems without MIMO

Mode coupling

Low to highSystems with MIMO

Low

Systems without MIMOSplicing

Low splice loss
Low cross coupling

Attenuation

Low all modes

Effective area

Large

Dispersion

LargeYour Optical Fiber Solutions Partner™

Requirements for Differential Mode
Delay (DMD) of few mode fibers in
MIMO based systems• DMD can be compensated by combining fibers with positive andnegative DMD.
• Local accumulated DGD not too high To minimize width of plateau in impulse respond R. Ryf et al., ECOC,12, Tu.1.C.1• Local DMD not too low to suppress intermodal nonlinearities
 R.-J. Essiambre et al., ECOC,12, Tu.1.C.4

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Fiber designs for few mode fibers• Step index fibers
 High DGD• Step index fibers with additional depressed cladding Low DGD possible for fibers supporting two LP modes• Graded index fibers
 Low DGD possible for few to many modes
 Optional with a trenchYour Optical Fiber Solutions Partner™

Some selected reported results
FiberdesignNo.
DMDof LPmodes

AeffAtten.

Producer

Reference

ps/m

µm2

dB/km

120 - 130

0.22

Prysmian

ECOC’11Tu.5.LeCervin.7< 0.30NTT

OFC’12 OM2D.1

0.196

Fujikura

OE’13 pp. 16231

Corning

OECC’12 5C3-2

SI

4+4.4 to +8.9

Two layerSI

2-0.4 and +0.4

GI

2~0GI

2-0.12 to +0.12 170-240

SI+Trench

2+0.05

160

0.205

OFS

OFC’11 PDPB10SI

22.3

160-210

0.186

OFS

OFC’12 OTh3I.4

GI+Trench

2+0.2 to -0.2

95

0.195

OFS

OFC’12 PDP5A.1

SI

4+2 to +4210 – 310

OFS

OFC’12 OTh3I.4

GI+Trench4-0.3 to +0.3

90 - 180

OFS

OFC’13, DP5.A.1

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150-200~0.20

6Characterization of Few Mode fiber

XIn
Modeconverter

Coupling/SpliceFiberundertestOut• Mode converter and the coupling to the FUT should assure highextinction of the mode under test to other modes• Coupling from the mode under test should be low to othermodes in the length of fiber under test.

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Example properties OFS two mode fiber
Property

Unit

DMD between LP11 and LP01

ps/m

Simulations

Measured-0.1 to +0.1
-20 dB/30 km

Distributed Mode coupling
Dispersion LP01

ps/(nm·km)

19.9

20.5

Dispersion slope LP01

ps/(nm2·km)

0.068

0.067

Effective area LP01

µm2

162163

Dispersion LP11ps/(nm·km)

22.1

22.2

Dispersion slope LP11ps/(nm2·km)

0.063

0.051

Effective area LP11µm2

172

Attenuation LP01

dB/km

0.190

Attenuation LP11dB/km

0.194

PMD LP01
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0.03
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Example, DMD variation along a fiber draw
from a single preform

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9Conclusion• Few mode fibers supporting two or four LP modes (3 or 6 spatialmodes) has been fabricated by several groups and successfully
use for transmission• Still possible to optimize properties• Still work to do to scale up number of modes• New requirements for characterization
 Area for future standardization work

This work was supported by theEU program FP7-ICT MODE-GAPYour Optical Fiber Solutions Partner™

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