1MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

White Paper

senko.com

MPO Connector
Random Mating IL versus
IL by Master Jumper
FEBRUARY 2024
Rev. 01

Bernard Lee
Andrei Vankov

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

MPO Connector
Random Mating IL versus
IL by Master JumperContents

4Introduction

4Insertion Loss (IL)

5Random Mating

7

Low-Cost MT vs Super-Low-Loss MT Evaluation

10Summary

11

Biography

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

Introduction
Optical connectors are one of the most important components in an
optical network as it provides the flexibility to quickly and reliably
establish a connection without needing any complex equipment
such as fusion splicers. However, they are also one of the componentsthat can cause network failure with high Insertion Loss (IL) and
Return Loss (RL). As higher bandwidth networks using 400GbE and800GbE transceivers are deployed, optical performance of connectors
becomes ever more crucial.
The increase in the demand for data intensive and latency sensitive
services such as video streaming, machine learning, and AI-driven
applications further increases the number of fiber links. This pushes
an exponential increase in the deployment of higher density multifiber connectors such as the MPO connector.

Unlike the more commonly used LC and SC single fiber connector,
multi-fiber connectors house multiple fibers, with some up to 32
fibers within a single connector housing. The failure of a single fiber
within the connector housing can have an impact on the rest of thefibers. A high level of connector quality in terms of its material, overall
dimensions, fiber positioning, and manufacturing must be of thehighest quality to comply with international standards.
As all the components have very tight tolerances in the microns,variability in these tolerances causes increased optical losses, even if
the patch cords are produced by the same manufacturer. In addition
to controlling the component tolerances, design considerations andtesting methods also contribute to optimal connector intermateability.

1.1 Insertion Loss (IL)As manufacturers need to have a reliable and repeatable method to test
their patch cords, a reference or master patch cord and adapter is used
as a control to perform these tests. A master patch cord is essentiallya near perfect patch cord, specifically in terms of the positioning of
the fiber core and its protrusion/undercut from the ferrule. The patch
cord test result against this master patch cord is what is measured andreported on the performance report that is provided to the end user.

The manufacturer’s IL values can only serve as a guidance on
the connector performance in a controlled environment. The IL
performance using a master patch cord will not be the same as out
in the field and can vary at the installation site where various random
patch cords are mated together using generic adapters. The higher
loss values recorded in the field is referred to as Random Matingloss. The only way to reduce Random Mating loss is by improving
manufacturing consistency and reducing tolerances.

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

1.2 Random Mating
Random Mating is a method of cross-mating patch cords fromdifferent manufacturers or manufactured batches from the same
supplier without the use of master patch cords or adapters. The
IEC 61300-3-34, “Fiber Optic Interconnecting Devices and Passive
Components – Basic Test and Measurement Procedures” standard,
specifies random mating procedures. These procedures are intendedto give an accurate expected optical loss in the field, including worst
case scenarios, taking complex interactions into account between all
factors including ferrule and fiber dimensions, end-face geometry,and polish surface quality. The standard describes test methods ofrandomly mated connector with randomly selected adapters toprovide an estimation of their expected performance.

The IEC 61753-1 standard specifies the random mating IL performanceand provides attenuation grades depending on their performance.
As multi-fiber connectors have additional design parameters andconstraints, another standard was developed. The standard thatoutlines the IL performance requirements for angled polyphenylene
sulphide rectangular ferrules with 2, 4, 8, and 12 fibers, such as theMPO connector, is the IEC 61755-3-31. This standard also outlines theoptical interface end-face geometry tolerances and three connector
grades which outlines random mating IL performances which are
Grade B, Grade C, and Grade D. Like the IEC 61753-1 standard, GradeA has yet to be defined.

Interface Dimensions Related to Lateral and Angular Offset
Key
2x OD
OE UCOA U VY

2x ODXYiVUxlBOJ

Rz < GK

Alignment Pin Geometry

Ref

Grade B

Grade C

Grade D

Units

Remarks

MinMaxMinMaxMinMax

A-

0.0016-0.0024-0.0034mm

Core position

B

4.598

4.602

4.598

4.602

4.597

4.603

mm

Hole pitch

C-

0.2-

0.2-

0.2o

Fiber angle error

D

0.699

0.6996

0.699

0.7

0.699

0.7mm

Diameter

E-

0.012-

0.012-

0.012

mm

Hole parallelism

G-

200-

200-

200mm

RMS roughness

J0.69840.6985

0.698

0.699

0.698

0.6990mm

Diameter

K-

0.005-

0.005-0.005mm

Cylindricity

Figure 1 EC 61753-1 optical interface enface geometry tolerances.

6MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

Grade B connectors are becoming a common requirement for many
telecommunication network and data center operators. This is toreduce the cost of transceivers and power consumption with lower
optical budget. In this paper, we focus on the Random Mating IL
requirements of a Grade B connector.

As an example, for a 12-fiber MPO connector, the theoretical IL yield %can be calculated as

12-fiber MPO
yield % with=Attenuation≤ 0.25 dB

Rectangular ferrule connector core alignment specifications are definedat the single channel level. A population of fiber links interconnectedwith Grade B rectangular ferrules will yield ≤ 0.25 dB IL for ≥ 97 % of allchannels with a mean of ≤ 0.12 dB. However, as multiple channels aregrouped in a single connector, the theoretical, worst-case connector IL
yield percentage for a completely random core alignment distribution
can be calculated as follows:

Multi-fiberconnector=attenuation
yield %

singlechannel
attenuation
yield %1297.293
or 71.94%

n= total number of populated fibers per ferrulen
The yield % of 4-fiber, 8-fiber, and 12-fiber connectors with various
attenuation levels are outlined in the table below.

n= total number of populated fibers per ferrule

Grade B Single Channel vs. Multi-fiber Connector Performance
Attenuation (dB)Single Channel
Cumulative %4-Fiber Cumulative %8-Fiber Cumulative %12-Fiber Cumulative %

0.25

97.29

89.60

80.29

71.94

0.30

98.71

94.92

90.10

85.53

0.35

99.41

97.66

95.37

93.14

0.40

99.72

98.90

97.81

96.74

0.45

99.87

99.49

98.98

98.48

0.50

99.94

99.75

99.49

99.24

IL max <0.25 dB for 97.29%
of channels

IL max <0.25 dB for 89.60%
of channels

IL max <0.25 dB for 80.29%
of channels

IL max <0.25 dB for 71.94%
of channels

Note: Mean = 0.07 dB

Figure 2 Grade B single channel vs. multi-channel connector performance.

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

1.3 Low-Cost MT vs Super-Low-Loss MT Evaluation
The dimension of the connector is not only crucial to ensure the properalignment of the connector, but it also has an impact on the assemblyand polishing processes. The specifications of a generic low-cost MT
ferrule and SENKO's super-low-loss MT ferrule are evaluated for the12-fiber MT ferrules.

ferrule is observed to have the X-axis eccentricity being shifted to thecenter of the ferrule, hence the fiber holes on the outer side has a muchlarger eccentricity error. It also has a much larger variation in the Y-axis
eccentricity. The high variability in eccentricity will result in a higher IL.

The fiber hole eccentricity is one of the most crucial attributes of afiber ferrule as it determines the position of the optical fibers that arewill be terminated to establish a connection. The generic low-cost MT0.80
0.60
0.40
0.200.00
-0.20
-0.40
-0.60
-0.80

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F120.80
0.70
0.60
0.50
0.40
0.30
0.20
0.100.00

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F120.80
0.600.400.200.00-0.20-0.40-0.60-0.80

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12Eccentricity SENKO
Eccenctricity µm

Eccenctricity µm

Eccentricity Generic

0.80
0.60
0.40
0.20
0.00
-0.20
-0.40
-0.60
-0.80

y

Y-axis Eccentricity SENKO
Eccenctricity µm

Eccenctricity µm

Y-axis Eccentricity Generic
0.80
0.60
0.40
0.20
0.00
-0.20
-0.40
-0.60
-0.80

X-axis Eccentricity SENKO
Eccenctricity µm

Eccenctricity µm

X-axis Eccentricity Generic

X

0.60
0.50
0.40
0.30
0.20
0.100.00
0.100.20

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12Figure 3 A comparison between generic low-cost MT and super-low-loss SENKO MT geometrical data.

8MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

The table below shows three tests which are the generic low-costconnector random mating, generic low-cost connector with masterpatch cord, and SENKO's super-low-loss connector random mating

WavelengthMax.

IEC 61755-3-31 Grademeasured in the 1310 nm wavelength. The reason for choosing
1310 nm is because it is more sensitive to misalignment than longer
wavelengths would be.

Avg.

≤0.25 dB

≤0.30 dB

≤0.35 dB

≤0.40 dB

≤0.45 dB

≤0.50 dB

≤ 0.12≥ 71.94%≥ 85.53%≥ 93.14%≥ 96.74%≥ 98.48%≥ 99.24%

Generic Connector
Random Mating

1310 nm

0.70

0.179

72.8%

80.8%

85.9%

90.6%

96.2%

98.1%

1550 nm

0.62

0.170

75.2%

83.8%

88.7%

93.7%

96.8%

99.1%

Generic Connector
with Master Patch
Cord1310 nm

0.36

0.097

94.4%

99.3%99.3%

100%100%100%

1550 nm

0.33

0.092

97.9%

99.3%100%100%100%100%

SENKO Super Low-LossRandom Mating

1310 nm

0.26

0.067

99.6%

100%

100%

100%

100%

100%

1550 nm

0.20

0.060

100%

100%

100%

100%

100%

100%

Comparison IL distribution of 12-fiber
MPO connectors @1310 nm, random mating

Comparison IL distribution of 12-fiber
MPO connectors @1550 nm, random mating

Figure 4 Comparison IL distribution of 12-fiber MT @1310/1550 nm, random mating between SENKO and Generic MPO connectors.

Comparing the test results with the IL standards outlined in theIEC 61755-3-31 standard performance grades, the generic low-costconnector does not meet the Grade B standard with the averageinsertion loss being greater than 0.12 dB for the 1310 nm and 1550 nm
wavelengths. In addition, the yield of connectors with IL below 0.30 dB,
0.35 dB, 0.40 dB, 0.45 dB, and 0.50 dB fall short of their respective yieldrequirements.

Comparatively, the SENKO super low-loss connectors under test fullycomply with the IEC 61755-3-31 standard performance grade with only
one connector having an IL of 0.26 dB at 1310nm, which gives it analmost perfect result. In addition, the average IL at 0.067 dB at 1310 nm
and 0.06 dB at 1550nm, are significantly lower than the requirement. Itis also observed that this result also passes the requirement under theIEC 61753-1 standard for single-fiber ferrule Grade B connectors.

9MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

MT Ferrule
16-fibers

IL distribution of 16-fiber MPO connectors withrandom mating @1310 nm and 1550 nm
Although the IEC 61755-1-31 standard does not outline multi-fiber
ferrules with more than 12 fibers, the 16-fiber and even 32-fiber
MPO connectors are widely used in data centers. As the number offibers in a single-ferrule housing increases, so do the challenges inmaintaining a reliable and low-loss connector. As a challenge, SENKO
put the super-low-loss 16-fiber MPO connector through the samerandom mating IL tests.
The results show that even with the higher fiber count, SENKO's superlow-loss MPO connector fully complies with the IEC 61755-3-31 andalmost even passes the IEC 61753-1 standard for single-fiber ferrule GradeB connectors that requires 97% of tested connectors having ≤ 0.25dB.

SENKO Super-Low-Loss 16-Fiber MPOMax.
IEC 61755-3-31 Grade B requirement

Avg.

≤0.25 dB

≤0.30 dB

≤0.35 dB

≤0.40 dB

≤ 0.12≥ 71.94%≥ 85.53%≥ 93.14%≥ 96.74%

SENKO Random Mating @ 1310nm

0.330

0.069

96.88%

98.44%

100%

100%

SENKO Random Mating @ 1550nm

0.300

0.057

99.69%

100%

100%

100%

Figure 5 SENKO's super-low-loss 16-fiber MPO random mating, surpasses the IEC 61755-3-31 Grade B requirements.

10MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

Summary
SENKO has refined the designs and manufacturing processes on its
range of super-low-loss MPO connectors to improve performance
during random mating to exceed the requirements outlined in the IEC
61755-1-35 standard. Optimizations have been made to the overall
dimensions, fiber hole eccentricity, and fiber hole tilt angle to improve
the IL performance repeatability. These design improvements
manifest themselves as lower and tighter optical losses during
random mating scenarios.
SENKO connectors have demonstrated their superiority overcompetitors by successfully passing the rigorous GR-1435 standards,
ensuring a reliable Multi-Fiber Optical Connector. GR-1435 setsstringent requirements for MPO interconnects, subjecting them tovarious environmental and mechanical stresses. Consequently, it isadvisable for end-users to request such data from their MPO provider
to guarantee reliability in the field. SENKO is ready to support withtest setup configurations and advise on how to replicate your own
Random Mating test at your facility.

In addition to meeting industry standards, a thorough interoperability
study revealed that, when testing MT-based connectors against
master cables, optical performance often remains high regardless ofconnector type. However, the real-world scenario in the field differsfrom laboratory conditions due to two key factors. First, technicians
may lack sufficient knowledge, proper end-face cleaning gear, andvisual inspection equipment. Second, connecting connectors fromdifferent manufacturers and not against master cable results in higher
losses than those reported in controlled laboratory environments.
SENKO’s MT super low-loss ferrules address these challenges
effectively by minimizing the impact of these factors. This is achieved
through superior guide pins alignment and meticulous attention
to fiber hole geometrical parameters, refined through years ofexperience and continuous improvement in Japan. As a result, SENKO
connectors offer a reliable solution that significantly reduces the loss
associated with interconnection in practical field applications.

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MPO CONNECTOR RANDOM MATING IL VERSUS IL BY MASTER JUMPER

Biography
Andrei Vankov, is an Application Engineer at SENKO Advanced Components. He received his BS from Thomas Edison
State College and his MSEE from Pennsylvania State University. He began his career in 1993 at Sumitomo ElectricLightwave Corp as a Fiber Optic Manufacturing Engineer where he worked on active and passive components using
Kaizen methods in Yokohama, Japan. As a Senior Optical Design Engineer in Franklin, MA (founded as Advanced Interconnect) Andrei Vankov developed various passive optical components and packaging integration to meet Telcordia
industry standards. He designed optical interconnects, including optical backplanes (MTP, HBMT, PHD, OGI), and afiber optic SMPTE compatible Broadcast Connector for HD applications. In 2013-2020 Andrei worked at Nokia division Radio Frequency Systems (RFS) where he provided leadership for an LTE RAN launch project team. Andrei holds
several US and European Patents in fiber optics interconnect technology.

Bernard HL Lee is currently the Regional Technology Director at SENKO Advanced Components. He started his careerin optical communications when he was appointed as a Senior Research Office for the European Union IST project
known as DAVID in 2000. In 2003, he joined Telekom Malaysia R&D where he has held various technical and management positions there including the Head of Photonic Network Research and also Head of Innovation and Communications. Bernard then joined the parent company, Telekom Malaysia (TM) in 2010 as the Assistant General Manager ofthe Group Business Strategy Division where he oversees the company’s business direction. Bernard is also a memberof the International Electrotechnical Commission (IEC), the Institute of Engineering and Technology (IET) and is also
the Director of the Board of the Fiber-To-The-Home Council APAC.

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