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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

White Paper

MAY 2021

GR-1435: Ensuring
a Reliable Multi-Fiber
Optical Connector
Dr. Bernard Lee, Emmanuel Kolczynski,
Andrei Vankov

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Exchange2GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

3GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

GR-1435: Ensuring
a Reliable Multi-Fiber
Optical Connector
Contents

4

Introduction

5

Why is there a need for GR-1435?

6

Introducing GR-1435

7

GR-1435 Test Criteria and Measurements

8GR-1435 General Requirements

9GR-1435 Test Criteria

12 What Failure Looks Like
13 Summary
14 Reference
14 Biography

4GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

Introduction
In 1985, Nippon Telegraph and Telephone (NTT) introduced MT ferrule

The most widely deployed multi-fiber connector in the market istechnology as a way to improve mass fiber connectivity and efficiency.

the MPO connector which features multiple fibers housed within

Multi-fiber Push-On, abbreviated MPO, is an MT ferrule-baseda monolithic ferrule. With so many suppliers in the market offeringfiber optic connector that was developed in the 1990’s as a way for

optical connectors, how does one ensure that the connector thatmechanical connectorization. The early adoption of MPO connectors

they are selling can perform well during deployment and throughout

was very slow due to high costs and low optical performance.

its life cycle? The quality, reliability, and performance of multi-fiber

In recent years with the ever-increasing demand for more bandwidth,connectors are assured not only by selecting superior components,

multi-fiber connectors have become one of the most important

but also by following a repeatable refined termination procedure,

components in optical network connectivity. As 100G/400G/800G

followed by a refined polishing process, and extensive testing withtransceiver technologies continue to gain popularity, more multi-fiber

top-of-the-line equipment.

connectors will be deployed to increase network density. However, as
history has shown, multi-fiber connectors are not without their own
challenges when compared to single fiber connectors. The mechanicalalignment of 12, 16, 24, 32, 48, and even 72 fibers between two pins as
wide as 5.3 mm is no small engineering feat.

Monolithic Multi-Fiber Connector

PLUG

Multi-Ferrule Multi-Fiber Connector

CABLE

KEY
MONOLITHIC FERRULE
COUPLING

GUIDE PINS

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

Why is there a need for GR-1435?
It is a very high hurdle to achieve GR-1435 certification. Does this mean that certified connectors will be more expensive? Why would
someone spend about twice as much on a connector just because it is certified?
The connector is just one small component in an intricate optical network. However, the connector has a significant impact on overall network
performance. Using non-certified components may save on capital expenditures upfront, but from a Total Cost of Ownership perspective, it will bea much higher cost with all the maintenance expenditures in the future. Unlike a single fiber connector where any failure will only affect a single
transmission, the potential disruption from a multi-fiber is much more severe.
Let’s use a 24-fiber MPO connector as an example, if deployed in a 400 Gbps parallel network, the connector failure would cause a catastrophic
failure. The damage would not only be limited to network failure, but also cause a loss in revenue, result in Service Level Agreement (SLA) penalties,
and reduce customer confidence.

Ruggedized Indoor
Fan-Out

Junction Box

36F Cable
MODU - FTTB

FTTA Network

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MPO
Trunk
Cable

MPO-LC
Fan-Out
72F Cable

12F Cable
FTTH Cabinet

MPO-LC
Fan-Out

FTTH Network

Splitter
ETP

Ruggedized MPO
Fan-Out

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

Introducing GR-1435
The GR-1435-CORE standard outlines the requirements,
features, performance criteria, and characteristics of
single-mode multi-fiber optical connectors. The standard outlines
qualification testing in two phases: 1) initial product qualification/
certification, 2) periodic verification to ensure that the product performs
within established parameters.
The GR-1435 standard outlines three different fiber/cable media types
for providing optical multi-fiber pathways. These three media types
vary in connector assembly robustness for diverse applications, suchas in back-plane connections or in an outside plant environment. The
three media types are:

Type I Media
Bare Ribbon Fiber• Type I Media: bare ribbon fiber• Type II Media: jacketed ribbon fiber• Type III Media: unreinforced single fiber with a buffer
or coating of approximately 0.9mm

GR-1435 is designed to test a connector’s lifetime performance andreliability through a series of service life performance tests, which
include environmental and mechanical tests. These tests are designed
to simulate stressors that a connector may experience during its lifetime
from manufacturing, storage, transport, operation, handling, and aging.
Furthermore, the GR-1435 standard outlines an extended service life
test to determine the long-term reliability of the connector assembly.
These tests are in addition to the standard service life performance
tests and are meant to identify possible weaknesses in the connector
assembly, design or materials.
The tests are usually performed on a set of 15 samples from the
manufacturer to establish a statistically valid sample size. To achieve GR1435 compliance certification, testing and reporting is performed by anaccredited 3rd party test laboratory, which is part of the requirement
for any manufacturer.

Type ll
Reinforced Jacket

Type III Media
Unreinforced Single Fiber

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

GR-1435 Test Criteria and Measurements
Before the multi-fiber connector assembly is put through rigorous testing conditions, we need to establish the initial condition andwhat changes (if any) are considered acceptable. The GR-1435 standard takes the grade of the connectors into consideration, which
are divided into Standard, High-Performance, and Ultra-Performance categories. The connector insertion loss and reflectance are measured
at 4 phases throughout the lifetime of the samples, these include as a new product, during testing not under load, during testing under load,
and at the end of the test.

Test

Maximum Insertion Loss (dB)Maximum Insertion Loss Change (dB)Standard(R)

High Performance(CR)

Ultra Performance(CR)

Standard & High Performance(R)

Ultra Performance(O)

New Product

0.70

0.50

0.35

-

-

During Testing,
Not Under Load

0.80

0.60

0.45

0.30

0.20

During Testing,
Under Load

-

-

-

0.50

0.30

End of Test

0.80

0.60

0.45

-

-

Test

Reflectance (dB)Standard(R)

High Performance(CR)

Ultra Performance(CR)

New Product

-55

-60

-65

During Testing,
Not Under Load

-50

-55

-60

During Testing,
Under Load

-50

-55

-60

End of Test

-50

-55

-60

(R) - Requirement(CR) - Conditional Requirement(O) - Objective

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

GR-1435 General Requirements
There are basic requirements that the multi-fiber connector assembly must satisfy for it to be considered for the service life performance
tests. The three main requirements are connector intermateability, fire-resistance, and fungal resistance.

Basic Requirements

Intermateability

The connector must meet a set of defined physical attributes withcouplings and plugs to ensure that connectors supplied from one suppliercan be mated with connectors from a different supplier. An example is themost common multi-fiber connector, the MPO connector, needing to becompliant with the EIA/TIA-604-5 Fiber Optic Connector Intermateability
Standards (FOCIS-5) standard and the IEC 61754-7 standard.

Fire-resistance

There is a range of flammability tests, such as the ANSI T1.307 and UL94,
that must be passed depending on the type of material used. The main
reason for this requirement is the possibility of the multi-fiber connector
assembly being used in an indoor environment, especially in FTTP and data
centers. Flammable materials or materials that emit too much smoke candamage surrounding equipment. Corrosive chemicals in the smoke may
also cause acidic condensation, which corrodes equipment over time.

Fungal resistance

Many additives such as lubricants, stabilizers, and plasticizers may be usedin the manufacture of the connector. These materials may promote fungal
growth, which digests these additives and secretes acids as a by-product.
These acids can then breakdown the resins to cause more damage.
Polymeric materials used for multi-fiber optical connectors must be
resistant to fungal growth. Fungal resistance is tested based on themethodology outlined in the ASTM G21 standard.

9GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

GR-1435 Test Criteria
The following table is a description of the Uncontrolled Environmental Tests performed on the connectors during the GR-1435 testing:Uncontrolled Environment

Thermal Aging

Connectors are subjected to high temperature of 85°C with uncontrolled
humidity for a duration of 168 hours. This test is the least severe of all theenvironmental tests and simulates and accelerated the processes that may
occur during product shipping.

Humidity Aging

Connectors are subjected to high temperature and humidity of 95%
relative humidity at 75°C for 168 hours. This test simulates the connector’s
condition in the second half of its service life with wear and tear,

Thermal Cycling

The thermal cycling test is performed to simulate conditions that theconnector assemblies may be exposed to in the outside plant environment
after a period of aging. This test is performed with cycles between -40°C to
75°C, as optical connectors may be installed in areas with temperatures atboth environmental extremes. This test is run for 168 hours as well.

Humidity/
Condensation Cycling

This test is performed to simulate worst-case condensation conditions that
may occur in outside plant environments, such as in enclosures or cabinets.
Since enclosures will usually warm up faster, the connector assemblies
remain below the dew point of the atmosphere within the enclosure, thus
causing condensation to deposit on the connectors. This test is designed
to exploit any physical imperfections, such as minor cracks, that would
allow water to enter , eventually causing the crack to expand when thewater freezes. The samples are exposed to 14 cycles over 168hrs withtemperatures going from -10°C to 65°C with 90-100% relative humidity.

Dry-out

The dry-out step is performed to dry the connector assembly before being
subjected to subsequent tests. The dry out step is 24 hours at 75°C.

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

The following table is a description of the Controlled Environmental Tests & Mechanical Tests performed on the connectors
during the GR-1435 testing:Controlled Environment
Thermal Aging

The controlled thermal aging test is performed to generate wear on theconnector assembly by simulating the conditions in the second half of its
service life. The connector assembly is subjected to a high temperature at
60°C for 96 hours.

Humidity Aging

This test is designed to simulate the conditions in the second half ofthe connector assembly’s service life with wear and tear. The connector
assembly is exposed to a temperature of 40°C at 95% humidity for 96 hours.

Thermal Cycling

The thermal cycle test simulates the exposure of an aged connector
assembly to normal operating environments. The connector assembly issubjected to five temperature cycles from -10°C to 60°C.

Dry-out

The dry-out step is performed to dry the connector assembly before being
subjected to subsequent tests. The dry out step is 24 hours at 60°C.

Vibration

The vibration test is designed to expose the connector assembly toenvironmental vibrations, such as those from passing traffic or the wind.
The connector is vibrated on all three main axes to simulate various
connector mounting positions.

Cable tension

Cable tension tests are designed to simulate the potential stressors thatconnector assemblies may be subjected to during normal operation.
Connector assemblies may be pulled, flexed, or twisted while underoperation. Test conditions vary depending on the media type.

Impact

The impact tests are designed to simulate the connector assembly use in
a controlled environment, as well as in an outdoor plant. This test assesses
the condition of the connector assembly after stressors experienced fromprolonged handling by technicians. It also tests the integrity of nonmetallic components by ensuring that the material maintains its nonbrittle behavior throughout the operating temperature range.

Durability

The durability test simulates the connector assembly mating and demating. As connectors are intended to enable quick changes in network
termination, they are expected to be disconnected and reconnected
multiple times over their lifetime.

Mechanical Testing

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

Following the service life tests, one last end of service life test is performed as a confirmation of the connector assembly performance.
This test is performed to quantify the cumulative effect of all service life tests that were performed on the connector assembly.
The following table is a description of the Extended Service Life Tests performed on the connectors during the GR-1435 testing:

Extended Service Tests

Extended Thermal
AgingThis test is similar to the service life thermal aging test, but is performed
for a much longer duration to simulate long term storage.

Extended Humidity
Aging

This test is similar to the service life humidity aging test, but is performed
for a much longer duration to simulate the operational service lifetime

Extended Thermal
Cycling

This test is similar to the service life thermal aging test, but is performed
for a much longer duration to simulate the operational service lifetime.

Salt SprayThis test is intended to simulate the installation of the connector assemblyin a harsh environment with high salinity, such as by the seaside. This test
also determines the rust resistance of the connector assembly’s metallic
components

Airborne Contaminants

This test simulates the installation of the connector assembly in anenvironment with a high concentration of contaminants and chemical
exposure

Dust

This test simulates the installation of the connector assembly in a dusty
environment, such as sandy beaches or deserts

Ground Water
Immersion

This test simulates connector assembly deployment in an undergroundenclosure where it may be potentially exposed to ground water or if
improperly installed.

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

What Failure Looks Like
The GR-1435 standard is one of the most stringent tests for multi-fiber connector assemblies, so it is expected that not all manufacturers
can pass all the tests. Some of the common defects observed are:Dimension Defect Adapter

Dimension Defect Connector

Connector dimensional non-compliance can result in mating andde-mating force issues. In the worst-case scenario, the latches on theconnector or adapter can break.
This image shows the latches broken off. This problem does not only posea risk to damaging patch panels, but can also damage the connector on
high-cost test equipment.

Another example of a connector dimensional non-compliance results inthe weakest section of the connector breaking off.
This image shows the side of an MPO connector broken off. This can becaused by misaligned pins and misaligned latches. Stress from repeatedmating and de-mating can cause such failures.

Material DefectUse of substandard materials can result in distortions, discoloration, andeven mechanical failure (such as cracking) when put through a series ofenvironmental tests.
This image shows a cracked MT ferrule that can no longer be used.

Material DefectAnother example of the use of substandard materials results in theinability of connectors to withstand stresses from normal operation.
This image shows an MPO connector that was subjected to a twist test.
The strain on the connector body caused it to break off at the base.

Manufacturing DefectOn top of good quality components, proper manufacturing proceduresand quality control are crucial to producing high quality connectors.
This image shows the failure of crimping the boot of the connector onto
the body, which resulted in it being pulled off when longitudinal stresses
were applied to it.

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

Summary
Network performance reliability relies heavily on the use of high-quality connector assemblies. Multi-fiber connector assemblies
that are GR-1435 compliant provide an assurance of the quality of connector components, as well as its manufacturing processes
and equipment, by adhering to a strict quality assurance program. When deploying and operating a high-speed transmission networks with
100G, 400G, or even beyond, service providers and installers need a reliable connector assembly from a trusted certified supplier.

GR
1435
COMPLIANT

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

References
1.
2.
3.
4.

GR-1435-CORE: Generic Requirements for Multi-Fiber Optical Connectors, Issue 02, May 2008.
International Electrotechnical Commission, IEC 61754-7-1: Fibre optic interconnecting devices and passive components - Fibre optic connector interfaces- Part 7-1: Type MPO connector family - One fibre row, Sep 2014.
International Electrotechnical Commission, IEC 61754-7-2: Fibre optic interconnecting devices and passive components - Fibre optic connector interfaces- Part 7-1: Type MPO connector family - Two fibre rows, Dec 2017.
Underwriters Laboratories, UL 94: Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, March 2013.

Biography
Dr. Bernard HL Lee is currently the Director of Technology & Innovation at SENKO Advanced Components. He started his career in
optical communications when he was a Senior Research Office for the European Union IST project known as DAVID in 2000. In 2003, hejoined 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 at the Group Business Strategy Division. Bernard is also an Expert at the International
Electrotechnical Commission (IEC), a Chartered Engineer (CEng) accredited by the Engineering Council of UK, a Professional Engineer(PEng) registered with the Board of Engineers Malaysia and also a BICSI Registered Communications Distribution Designer (RCDD).
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 Electric Lightwave 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 opticalcomponents and packaging integration to meet Telcordia industry standards. He designed optical interconnects, including optical
backplanes (MTP, HBMT, PHD, OGI), and a fiber 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 a LTE RAN launch project team. He was
responsible for engineering, design and cost estimating of fiber optic builds for microwave and cell tower projects, defining design
criteria and completing initial planning and cost estimates of fiber optic projects in North America. Andrei holds a number of US andEuropean Patents in fiber optics interconnect technology.
Emmanuel Kolczynski is an Application Engineering Manager at SENKO Advanced Components. He is from Ottawa, Canada where
he attended Carleton University and completed his Bachelor of Engineering, with a focus in Electrical. He began his fiber optic careerwith JGR Optics Inc. in 2013 as an Application Engineer, helping companies globally with production processes and various testingneeds. He eventually became a Product Line Manager to help guide the company business direction by making strategic decisions
based on market trends and planning a future road map. At SENKO, Emmanuel applies his fiber optic knowledge and expertise tohelp with the design, testing, and release of critical interconnect technology for use in a constantly evolving market. He is currently
a member of the Telecommunications Industry Association (TIA) to follow the latest in industry standardizations and developments.
Emmanuel has a passion for technology and being able to reach the fullest potential through constant innovation and developments.

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GR-1435: Ensuring a Reliable Multi-Fiber Optical Connector

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