Fiber Certification: The Impact of New Standard forThe Impact of New Standard for Multimode Fiber Measurements

Dr. Andre Girard and Dr. Gang HeEXFO Electro-Optical EngineeringEXFO Electro Optical Engineering

OUTLINE

Introduction- Introduction

- Experiments performed on various Linksp p

- Experimental results

- Conclusion

Measurements on MMF LinksMeasurements on MMF Links

Multimode Fiber Link

Multimode Connectors

andPatchcords

(CW) Light Source (LS)or

O

Powermeter (PM)

OTDR

How Many Acronyms Do We Need to Remember?

• CPR: Coupled Power Ratio• EF: Encircled Flux• FF: Far Field• HOMP: High Order Mode Power• MMF: Multi-Mode Fiber• MPD: Mode Power Distribution• NF: Near Field• OFL: Over-Filled Launch• RP: Relative Power (%)RP: Relative Power (%)• SMF: Single-Mode Fiber

9 Types of MLCs (!?#$%)1. OFL + 1 km of MMF

2. 70 / 70 launch

3. OFL + Mandrel

4 CPR4. CPR

5. HOMP

6 NF / FF with diameter6. NF / FF with diameter requirements for RP at – 5 % or– 75 %, 15 % and 5 %

7. MPD Template

8. EF Template = target with upper and lower limits

Review of Current MLCs:Review of Current MLCs: (1) 1-km MMF after OFL

(2) 70/70 launch

f ¨ ¨

(2) 70/70 launch(3) Mandrel after OFL

• Define ¨How to do it¨; but…– Better define what you get than how to do it!

• Practically under-fill launch

Methods (1) and (2) not practical in the field• Methods (1) and (2) = not practical in the field

• OFL definition = “fuzzy” MLC = “fuzzy”

Review of Current MLCs:(4) Coupled Power Ratio (CPR)

F MMF t SMF• From MMF to SMF

• Defined at source output

• Simple/easy-to-do NF power distribution measurement

W k l if ll ll d NF PD– Works only if well controlled NF PD

• But with little information on high-order modes (HOM)g ( )– Loss = dependent on HOM power distribution

Review of Current MLCs:(5) High-Order Mode Power (HOMP)

• Power difference (in dB) with and without HOM filterPower difference (in dB) with and without HOM filter acting as a mandrel

• Works with OFL = but causes bad measurement• Works with OFL = but causes bad measurement reproducibility, because:

Size of fiber core– Size of fiber core– Macro-bending dependence – Too many transient losses

• Not widely used in the industryNot widely used in the industry

Review of Current MLCs:(6) N d F Fi ld (NF / FF)(6) Near and Far Fields (NF / FF)

NF Power Distribution 850nm

FF Power Distribution850nm 50μm

• Good control• Need both NF and FF test equipments• Need both NF and FF test equipments• Used internally as reference metrics

Review of Current MLCs: (7) MPD T l t d (8) EF T l t(7) MPD Template and (8) EF TemplateMPD Template EF Template

e po

wer

5 um, .0688 - .1061EF RADIAL BOUNDS

20um 8948 924715 um, .5838 - .697710 um, .2690 - .3820

F

Rel

ativ

e

OFLTARGETTEMPLATE

22 um, .9645 - .976720 um, .8948 - .9247

mal

ized

EF

Normalized mode group number Nor

mBoth obtained from NF power distribution:

MPD bt i d f d i tiRadius

• MPD obtained from power derivation• EF obtained from power integration

Advantages of EF Template• Not sensitive to noise fluctuations• Reproducible and repeatable measurements• With EF template, slight

under-filled MLCs: goodgcorrelation between loss and connector lateral

ffoff-set• In a multi-connector link

using EF target MLCs: the loss of a connector does not depend on itsdoes not depend on its location

OTDR versus LSPM

• Many studies done with LSPM

• Not much done with OTDR

• For instance: compared to LSPM does the OTDR:• For instance: compared to LSPM, does the OTDR: – Measure the same loss?– Have the same limits for obtaining 10% loss

accuracy? – Give the same ORL?

We will now answer these questionsWe will now answer these questions

Loss Issues with MMFLoss Issues with MMF

3 main loss contributors + an effect in a MMF li k b d b OTDRlink probed by an OTDR:

1 Connector loss due to lateral offset1. Connector loss due to lateral offset

2. Long MMF

3. Macro-bending

4. The OTDR pulses traverse the Link twice with additional mode scrambling effectswith additional mode scrambling effects from backscattering

Experiments Performed With MMF LinksE i l S Thi i i !Experimental Set-up - This is it!

Multimode Fiber Li k

Variable Mode LinkMode

Conditioner

Launching diti

Speckle Scrambler Launching

Cable conditions

OTDR Light Source =

(50m)

850nm / 1300nm Powermeter

850nm / 1300nm Fabry-Perot Laser

Experiments Performed With MMF LinksLi k T T d

Variable M d

Link Types Tested50/125µm fiber

Mode Conditioner

Speckle Scrambler Launching 2km 1km

OTDR Light Source =850nm / 1300nm

ScramblerCable (50m) Splices Long Link

850 / 300Fabry-Perot Laser PM

20m 50m 50mShort Link

18mm-10 turns Mandrel

M b di Li k25m 25m

Macro-bending Link

Experiments using EF Launch Conditions p gLoss Measurements at

850 nm 1300 nm1

0.80.9

1

UFL

EF LBEF TargetEF HB

0.50.60.7

aliz

ed E

F UFL EF HBMLC0MLC1

C2

0.20.30.4

Nor

ma

OFLMLC2MLC3MLC4

00.10.2

5 10 15 20 25

MLC5MLC6

5 10 15 20 25

Radial (um)

Long LinkExperimental results Loss vs. MLCs

850 nm 1300 nm

Short Link

OTDR(Total)LSPM(Total)LSPM(Total)

Macro-bending Link

17

Macro-bending Link

Experimental results ORL MLC55

L Li k ORL vs. MLCs

45

50

)

Long Link

Short Link

35

40

OR

L(dB

25

30

35

250 1 2 3 4 5 6 7ORL(Total)_850nm

ORL(C1)_850nmORL(C2)_850nmORL(C3) 850nm

ORL(C1)_1300nm

ORL(C3)_850nmORL(Total)_850nmORL(C1)_1300nmO (C )ORL(C2)_1300nm

ORL(Total)_1300n

ORL(C2)_1300ORL(C3)_1300nmORL(Total)_1300nm

OTDR Experiment results vs. MLCsConnectors and Macro-bending Losses

New Proposed MC ArtifactMandrel

2 5

S1 18mm10 turns 50/125 fiber

25m 25mC1 C2

Mandrel50m

2

2.5

ectio

n

C1+S1C2C2+M d

1

1.5

ding

/con

neos

s (d

B)

C2+MandTotalC1+S1+C2

0.5

1

Mac

robe

nd Lo C1+S1+C2Mand

00 1 2 3 4 5 6

Mode Launching Condition(MLC)

Conclusions

Experiments were performed =

Compare losses of 50/125 MMF at 850nm and 1300nm by OTDR and LSPM for 3 types of links

1. A Link with a few km length (Long link)

2 A li k ith h t l th (100 ) d2. A link with a short length (100 m) and many connectors (6) and splices (3)

3. A short link with macro-bending

4. All with various launching conditionsg

Conclusions

With Encircled Flux Template, it was shown that:

• Loss varies less in Long Links than in Short Links

• In Long Links, loss does not vary much at 850nm

In general loss varies less at 850 nm than at• In general, loss varies less at 850 nm than at 1300nm

• The loss measured by OTDR or LSPM exhibits good agreement

ConclusionsConclusions

With Encircled Flux Template, it was shown that:

• OTDR and LSPM loss = same behavior for any 3 Link types3 Link types

• 70/70 MLCs do not work with OTDR and LSPM i ll i Sh t Li k ” ithLSPM, especially in Short Links” with multiple connectors and macro-bending

• ORL is insensitive to MLCs

ConclusionsAnd Finally…

• At last, the Encircled Flux Template provides At last, the Encircled Flux Template provides MPD maintaining launch

• Reconciles MMF link• Reconciles MMF link loss measurements using either LSPM and OTDR

• A new physical MLCs artifact is proposed andartifact is proposed and recommended for OTDR– VerificationVerification– Qualification, and – Calibration

Thank you very much for your attention; andThank you very much for your attention; and…