Optical Fiber Connector Handbook - Senko Fiber Connector Handbook - ver… · 4 1White PaiprJP...

1OPTICAL FIBER CONNECTOR HANDBOOKWhite Paper JUL 2017

Optical Fiber Connector Handbook

Bernard LeeTom Mamiya

2OPTICAL FIBER CONNECTOR HANDBOOK


Contents


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Introduction to SENKO

Basic of Optical Fiber

Introduction to Optical Fiber

Optical Fiber Connectivity

Fiber Optic Connectors

Basics of Fiber Optic Connectors

Fiber Optic Connector Assembly

Connector Assurance (GR-326-CORE)

Service Life Test

Extended Service Life Test

Random Mating Loss Performance

Connector Testing

Insertion Loss

Return Loss

Introduction to Test Equipment

Power Meter & Light Source

Limitations

Optical Time Domain-based Measurement (OTDR)

Limitations

Backscatter Coefficient Settings

Index of Refraction (IOR)

Mode Field Diameter (MFD) Mismatch

Dead Zone

Helix Factor


Contents


Optical Continuous Wave Reflectometer (OCWR)

Limitations

Testing Procedure

Insertion Loss Measurement with Power Meter & Light Source

Cut-back Method

Substitution Method

Insertion Method

Insertion Loss Measurement with OTDR

Return Loss Measurement with OTDR

Return Loss Measurement with OCWR

Connector Hygiene

Overview

Optical Connector Ferrule & Contamination

Inspection Standards

Inspection Tools

Inspection Tools for MPO Connectors

Cleaning Tools

Cleaning Challenges for MPO Connectors

IEC Connector Type

IEC 61754-2 BOFC Connector

IEC 61754-3 LSA Connector

IEC 61754-4 SC Connector

IEC 61754-5 MT Connector

IEC 61754-6 MU Connector

IEC 61754-7 MPO Connector

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39.1

39.2

39.3

39.4

39.5

39.6


Contents


IEC 61754-8 CF08 Connector

IEC 61754-9 DS Connector

IEC 61754-10 Mini MPO Connector

IEC 61754-12 FS Connector

IEC 61754-13 FC Connector

IEC 61754-15 LSH Connector

IEC 61754-16 PN Connector

IEC 61754-18 MT-RJ Connector

IEC 61754-19 SG Connector

IEC 61754-20 LC Connector

IEC 61754-21 SMI Connector

IEC 61754-22 F-SMA Connector

IEC 61754-23 LX.5 Connector

IEC 61754-24 SC-RJ Connector

IEC 61754-25 RAO Connector

IEC 61754-26 SF Connector

IEC 61754-27 M12 Connector

IEC 61754-28 LF3 Connector

IEC 61754-29 BLINK Connector

IEC 61754-30 CLIK! Connector

IEC 61754-31 N-FO Connector

IEC 61754-32 DiaLINK Connector

IEC 61754-34 URM Connector

Biography

39.7

39.8

39.9

39.10

39.11

39.12

39.13

39.14

39.15

39.16

39.17

39.18

39.19

39.20

39.21

39.22

39.23

39.24

39.25

39.26

39.27

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Introduction to SENKO

SENKO Advanced Components is a wholly owned

subsidiary of the SENKO Group, which is headquartered

in Yokkaichi, Japan. From its humble beginnings in 1946, the SENKO

Group currently has an estimated annual revenue of $1.4 billion

globally. SENKO Advanced Components itself has 14 offices and

dozens of design and manufacturing facilities providing local support

to customers all around the globe.

SENKO Advanced Components develops, manufactures, markets and

distributes over 1000 fiber optic products for the telecom & datacom

industries worldwide.

SENKO Advanced Components was incorporated in the United States

in the early nineties and has since being recognized as one of the

industry’s specialists in passive fiber optics interconnect and optical

components.

An ISO-9001 approved company, SENKO is able to provide

multinational corporations with the technical expertise to liaise

with engineers, and the manufacturing flexibility to develop custom

products for the ever growing high tech industry.

Many of our products were created to resolve a specific design

challenge faced by our customers. We offer one of the industry’s

largest product portfolios, and our quality is second to none.

Our mission is to be the best global provider of passive fiber optic

components. We strive to provide an extensive portfolio of high

quality products and services, available on a global scale, with

excellent delivery time. We will stand by products, providing our

customers with superior post-sales support.

Our customers, suppliers and partners are essential to our success, and

shall be treated with respect and integrity. Our team is committed to

understanding the technical requirements and service expectations

of our customers, and share the goal of resolving the specific

challenges these clients face in their own business.


Introduction to Optical Fiber

Optical Fiber Connectivity

The use and demand for optical fiber networks has experienced

exponential grown over the past years. Optical fiber networks

are widely deployed for various applications ranging from global

telecommunications, signaling to desktop computers. These includes

the transmission of voice, data and video over short distances of

meters to hundreds of kilometers across continents.

Optical fiber is also used in systems for reliable and secure

transmission of data and financial information between computer

terminals, companies and countries around the world. Cable television

companies also use optical fiber to deliver data services and digital

video content to consumers. With the introduction of online video

streaming and higher definition video such as the 4K format and

the upcoming 8K format, optical fiber is required to deliver higher

bandwidth connectivity.

Optical fiber also enables new technology, application and services

such as remote learning and tele-medicine through transmission

of digital content and low latency control of remote devices. Other

applications for optical fiber includes automation, automotive,

industrial, space and military.

In order to build an optical fiber network, optical connectivity is required to extend, branch or split an optical fiber. There are mainly three

methods to terminate an optical fiber, which are fusion splicing, mechanical splicing and optical connectors.

Fusion splicing is the process of welding two optical fibers together. This is usually done by using and electrical arc in a fusion splicer. The ends

of the two optical fibers are melted and forms a continuous bond. This method results in the lowest attenuation and reflectance. It also provides

the strongest and most reliable joint between two fibers.

Mechanical splicing is the process of jointing two optical fibers through a mechanical splice unit. The mechanical splice is a self-contained unit

that has a V-groove which aligns the optical fiber within the unit. The two fibers are butted against each other with some index matching gel

to improve the optical transmission. Mechanical splicing is a non-permanent connection.

An optical connector is a termination at the end of an optical fiber that enables a quick and flexible fiber mating and demating compared

to splicing. The connectors are mechanically coupled to align the fiber cores. Fiber optic connectors are usually used in situations that require

quick fiber termination or increased flexibility such as in cross connection panels and customer premises termination.

Basics of Optical Fiber

Wireless

Telco/FTTx

Silicon Photonics/ On-Board Optics

Data Centers

Security

Medical Fiber Optic


Fiber Optic Connectors

There are many types of optical connectors. Different types of

connectors are used depending on the equipment and application.

Optical connectors have been designed throughout the years either

for specific application, improving on existing connector quality or

to increase connection density. Optical connection are available for

different types of fiber such as glass optical fiber, polymer optical fiber

and plastic optical fiber. In addition, connectors are also available for

both single mode and multimode networks.

A good connector design is determined by factors such as low

coupling loss, interchangeability, ease of assembly, environmental

resilience, high reliability, ease of connection, repeatability and low

cost of manufacture and operation. There are many different types

of connectors which use a variety of techniques for coupling such as

bayonet, screw-on, latched and push/pull.

Fiber optic connectors are mostly butt joint type connection where

the optical fiber is secured in a precision alignment sleeve called a

ferrule. Two connector ferrules are aligned and butted against each

other within an adapter to complete the fiber optic connection. There

are two commonly used butt-joint alignment designs which are the

straight sleeve and tapered sleeve.

Basics of Fiber Optic Connectors

Straight Sleeve

FiberFerrule

Alignment Sleeve


Fiber Optic Connector Assembly

• The connector boot and crimp eyelet is slotted through the fiber cord

• The cord is then stripped to expose the Kevlar and fiber buffer within the cord

• The fiber buffer is then stripped to a certain measurement to expose the optical fiber and cleaned

• A mixture of epoxy is prepared to be used as adhesive for the optical fiber in the ferrule

• The connector ferrule is connected to a pump which sucks the epoxy into the connector ferrule

• The prepared optical fiber is then inserted into the connector ferrule

• The connector ferrule with the optical fiber is then placed in an oven for curing

• After the connector ferrule is cured, excess fiber protruding out of the ferrule is carefully cut

• The connector ferrule is now ready for polishing.

STEP 1/3AdHESION

There are generally 3 steps in the optical fiber connector assembly which are adhesion, polishing and assembly. In this example, the general

method of connectorizing an optical cord is outlined.

boot, bare buffer

boot, short

crimp eyelet

connector sub-assembly

connector housing

dust cap

fiber ferrule


• The prepared connector ferrule is then affixed onto a ferrule holder jig

• The jig is then secured onto a polishing machine above a polishing pad

• Depending on the connector ferrule type and connector polishing requirements, suitable polishing films and

polishing program are chosen

• A piece of polishing film is placed onto the polishing pad. The initial polishing uses a coarse film

• The polishing machine is started. Distilled water is added to help smoothen the polishing

• The polished connector ferrule is then rinsed by using an ultrasonic washer

• The connector ferrule is then polished again by using a finer polishing film and rinsed after finishing

• This step is repeated as many times as required with the suitable polishing film until it is ready for assembly

• After polishing, the ferrule endface is examined by using an interferometer to ensure the prepared ferrule is within

the acceptable tolerances

• If the connector endface ferrule is not within the acceptable limits, the endface ferrule can be re-polished but this

can only be done for a limited number of times before the ferrule is rendered unusable.

STEP 2/3POLISHINg

After rough polishing

After fine polishing

After medium polishing


• After the connector ferrule passes the interferometer testing, connector assembly can begin

• The connector ferrule is slotted into the subassembly then few drops of epoxy can be added to the end of the

subassembly where it is to be crimped

• The connector Kevlar is then spread around the end of the subassembly

• The crimp eyelet is then slotted over the Kevlar and subassembly then crimped to secure the cord Kevlar

• The boot is then slotted over the crimp eyelet and pushed toward the subassembly

• The connector housing is then slotted over the subassembly according to the connector orientation

• The connector ferrule is then cleaned and the dust cap is slotted over the connector ferrule to complete the connector

production.

STEP 3/3ASSEMBLy


As demand for optical connectors increases globally, so does the

supply. When one visits trade shows, one will find numerous suppliers

offering from basic components to finished cable assembly products.

One key fact that end users have discovered in recent years is ‘not

all connectors are equal’. The quality, reliability, and performance of

optical components and cable assembly products such as patch cords

are assured by selecting the best components and by terminating and

polishing with the best equipment and procedures. These components

and procedures must assure that the jumper assemblies meet or

exceed the requirements of all pertinent industry specifications such

as the internationally recognized GR-326 standards.

This paper describes the relevance of the criteria in the applicable

industry specifications, as well as the importance of the physical

parameters and how they relate to the performance of the jumper

assembly.

GR-326-CORE (Generic Requirements for Singlemode Optical

Connectors and Jumper assemblies) was initially created by Bellcore

and continues to evolve as one of the more popular standards in

the telecommunications industry. Bell Communications Research,

Inc. or Bellcore was established in the early 1980’s by the Regional

Bell Operating Companies (RBOC’S) upon their separation from

AT&T. Bellcore served as the research and development, training

and standard setting arm for the RBOC’s. Following a divestiture

of the company in 1996, Bellcore was officially renamed Telcordia

Technologies in 1999. In 2012 Telcordia was acquired by Ericsson.

GR-326-CORE was written as part of Telcordia’s General Requirement

series to be consistent with the Telecommunications Act of 1996 and

it is intended to be the industrial specifications for long haul high-

speed applications such as telecommunications and cable TV.

There has been a total of four issues of GR-326, initial release, Issue

2 December 1996, Issue 3 September 1999 and the current Issue 4

February 2010. The Telcordia views in any particular release are

developed from the expressed needs of the Telcordia Technical Forum

(TTF), the TTF is made up from the companies who participated in the

development of each new issue.

As networks evolve and new products are offered the standards are

typically reviewed to see if there are changes that need to be made

or criteria added. A good example of this was the addition of four

wavelength testing (1310nm, 1490nm, 1550nm, 1625nm) in GR-326

issue 4, this was added because of the heavy use of connectors and

cable assemblies in FTTH networks. Field data is also a very important

part of the process when determining the need for reissues of the

standard. As some of the current networks have been in service for

many years, review of FIT (failure in time) rates along with post mortem

investigations provide invaluable data about the components

long term reliability. When the standards are developed, there are

many other industry standards that are referenced. Standards from

IEC, TIA/EIA, ASTM, ISO, ITU, UL as well as other Telcordia General

Requirement standards are referenced for test procedures, test

criteria, intermatebility criteria etc. When these standards are updated,

they need to be reviewed to determine if a GR-326 reissue is needed

to bring them in line.

The purpose for GR-326 is to determine a connector or connector

assembly’s ability to perform in various operating conditions, and to

determine long term reliability.

Connector Assurance (gR-326-CORE)

GR 326CORE


The GR-326-CORE test is one of the most comprehensive testing methodologies which will not only test the product’s material and

manufacturing precision but also the quality of workmanship. A full test will take a minimum of 2000hrs with multiple tests running in parallel.

As mentioned earlier, the GR-326-CORE test is divided into two main tests (i.e. Service Life Tests & Extended Service Life Tests). In the majority

of cases, when a sample is requested, a ‘golden sample’ will be provided which will most definitely pass all tests with flying colors. Hence, one

should always ask for a GR-326-CORE compliance certificate which is issued to manufacturers whom has passed the GR-326 compliance test at

any accredited 3rd party test laboratory in the world.

List of Main Test Categories

general Requirements These General requirements cover documentation, packaging, design features, intermateability, product markings and safety

Service Life TestingA sequence of environmental and mechanical tests that simulate possible conditions the connectors or connector assemblies may be under while in service

Extended Service Life Testing

Various tests intended to determine long term reliability of the connector or connector assemblies. Usually a simulated 25 year lifetime

Reliability Assurance Program

The program focuses on requirements for the manufacturing process that relate to long term reliability and performance of the finish product. Also includes additional testing to ensure the stability of the manufacturing process

The standard is broken down into 4 main categories as shown in table below:


Service Life Test

GR-326-CORE Environmental Service Life Test

Thermal AgingThe Thermal Age Test is considered the least extreme of the environmental tests in terms of stress applied, and is intended to simulate and accelerate the processes that may occur during shipping and storage of the product. Connectors are subjected to a temperate of 85 degrees Celsius with uncontrolled humidity for duration of 7 days, with measurements taken before and after testing.

Thermal Cycle During thermal cycling, the temperature fluctuates over an expansive range, subjecting the product to extreme heat and cold. Thermal cycling involves changing the ambient temperature of the connector by 115 degrees Celsius (75° to -40°) over the course of three hours. Heavy stresses and strains will be applied to each of the materials in the product. This test will also expose any weaknesses in the termination. If the design and procedures are not optimal, this can lead fiber cracks or breakage.

Humidity AgingHumidity aging is designed to introduce moisture into the connector and to determine the effect that the moisture has on the samples. This test is performed at the elevated temperature of 75 degrees Celsius for 7 days, while the connectors are exposed to 95% RH (relative humidity)

Humidity/ Condensation Cycle Humidity/Condensation cycling is performed in order to determine the effect that water has on the connector when a rapid transition in moisture occurs. This can cause water molecules to freeze or evaporate within the connector assemblies, potentially exposing “gaps” in the physical contact between connectors within an adapter. This phenomenon may have previously been masked by the water acting as an optical intermediary. The purpose is to achieve heavy condensation, so as to simulate a worse-case condition that may occur in outside plant applications.

dry-out StepThe product is exposed to a drying step at 75 degrees Celsius for 24 hours before the Post-Condensation Thermal Cycle is performed. The purpose is to remove any moisture that may remain from the previously performed Humidity/Condensation Cycling.

Post Condensation Thermal CycleThis is identical to the Thermal Cycle that was previously performed. The changes that may occur in the connector during Humidity/Condensation cycling are often revealed once the condensation is removed (as is the purpose of the ‘Dry-Out’ step), and these changes can potentially affect the loss and/or reflectance of the connector.

The function of the Service Life test is to simulate the stresses a connector may experience during its lifetime. The test is divided into two

sections namely the Environmental Test & Mechanical Tests. The Environmental Tests are NOT ONLY performed to ensure the jumper assemblies

will be able to withstand prolonged exposure to 85°C or temperature fluctuations of up to 125°C but also to accelerate the effects of aging on

jumper assemblies. Details of each of the test are explained in the following table.


TaBLE 3 GR-326-CORE Mechanical Service Life Test

Vibration Test In a vibration test, the products being tested are mounted to a “shaker.” By stressing the connectors in this fashion, the test will reveal whether high frequencies of vibration induce performance change in the connectors being tested. The test is conducted on three axis for two hours per axis at an amplitude of 1.52mm with the frequency sweeping continuously from 10 and 55 Hz at a rate of 45Hz per minute.

Flex Test The purpose of performing the flex test is to simulate stresses on the terminated cable and mated connector that could be incurred over the life of the connector. The boot, in particular, is important in this test, as it serves as one of the main points of strain relief. Thus, if the materials in the boot are inadequate, the boot may not function as intended. In addition, this will confirm that the fiber will not become uncoupled from the connector under such circumstances.

Twist TestThe twist test puts a rotational strain on the fiber, which tests the strength by which it is coupled with the connector. In addition, the adequacy of the crimp will also be tested. This, like the flex test, will help to identify weaknesses in the termination process.

Proof Test Proof Testing ensures the strength of the latching mechanism of the connector, as well as the crimp during the termination process. Should the jumper assembly receive a sudden tug after installation, this test ensures that the jumper assembly will neither break nor pull out of the adapter.

TWAL (Transmission With Applied Load) TWAL testing will stress the samples by applying different weights at multiple angles. The series of weights used depends on the media type of the cordage, as well as the form factor. Small Form Factor connectors are subject to a more extensive range of measurements.

*Note: Live measurements are made while the samples are under stress; this is done to reflect any degradation in transmission that might have incurred while the product is stressed in the field.

Impact TestImpact Testing is performed to verify that the connectors are not damaged when they are dropped. A cinderblock is mounted to the bottom of the fixture, approximately 1.5m from the horizontal plane that the connector will be dropped from. The connector contacts the cinderblock, and the process is repeated 8 times.

durability Test Durability testing is designed to simulate the repeated use of a connector. This test involves repetitively inserting (200 times) the connector into an adapter; this is done at different heights (3 ft., 4.5 ft., and 6ft) so as to simulate what a user in the field might encounter when standing in front of a telecom rack. The test can potentially reveal any problems with the design and/or material flaws in the connector, such as any part of the latching mechanism that may be heavily strained or flawed by frequent use

There are several mechanical tests (Figure 6) required to be performed once the aging is complete. These include: Flex Testing, Twist Testing,

Proof Testing, Impact Testing, Vibration Testing, Durability, and Transmission with an Applied Load. Again, details of each of the test are

explained in Table 3.


dust can seriously impair optical performance. Particles that contaminate endface can block optical

signals and induce loss. Whether or not the dust particles find an exposed path to a ferrule endface is

largely a matter of probability. Over time, dust particles will find their way to the optical connection if it is

possible. While the dust particles are not difficult to remove, the cleaning process involves disconnecting

the connector, which not only stops the transmission, but also exposes the endface to additional risk of

contamination. This test involves intense exposure to a dust of specified size particles in order to determine

if there is a risk of any particle finding its way to the ferrule endfaces.

Salt Fog (referred to as Salt Spray) is performed to guarantee the performance of the jumper assembly in

free breathing enclosures near the ocean. This test involves exposing the connector to a high concentration

of Sodium Chloride (NaCl) over an extended period. After the test, optical testing is performed, followed by

a visual inspection to confirm that there is no evidence of corrosion on the materials.

The Airborne Contaminants test is designed to guarantee the performance and material stability of

connectors in outdoor applications with high concentrations of pollution. The test repeatedly exposes

mated and unmated connectors to various gases and inspects the connector not only optically, but also

performing the same visual examination as in the Salt Fog test. An assortment of volatile gases is used in a

small chamber for 20 days to simulate prolonged exposure to these elements.

The materials are also verified in the Immersion/Corrosion test. This test has no optical requirements,

but instead involves a prolonged submersion in uncontaminated water. This test, like Dust, Salt Fog, and

Airborne Contaminants, involves both mated and unmated connectors. Mated connectors are checked for

ferrule deformation by measuring the Radius of Curvature before and after the test, and comparing the

values. If the ferrule is not geometrically stable during this test, it could be an indication of a flaw in the

zirconia material used in the ferrule. Unmated connectors are checked for Fiber Dissolution, which involves

checking to see if the fiber core has not recessed too far into the fiber cladding.

The final exposure test is groundwater Immersion.This test verifies the ability of the product to withstand

underground applications. The Immersion/Corrosion test is strictly to verify the materials involved, and

uses de-ionized or distilled water. Connectors deployed in underground environments are much more

likely to be exposed to contaminated mediums if their enclosures fail. During this test, the connector is

exposed to a variety of chemicals found in sewage treatment and agricultural fertilization, among other

applications, as well as biological mediums. These chemicals include ammonia, detergent, chlorine, and

fuel. Presence of these chemicals can have a detrimental effect on the materials comprising the connector

and adapter, reducing optical performance.

The criteria for connector and jumper assembly extended service life testing are exclusive to GR-326-CORE. The testing includes

exposure to a variety of environments, including additional Environmental Testing and Exposure Testing. The additional Environmental

Tests include extended versions of the Thermal Life, Humidity, and Thermal Cycle. These tests, which run for at least 2000 hours each (83 days),

are further studies in the life of the connector across a range of service environments. Testing is non-sequential, so there is no cumulative effect.

The Exposure Tests include Dust, Salt Fog, Airborne Contaminants, Ground Water Immersion, and Immersion/Corrosion. During the extended

Environmental Testing, many of the extruded compounds used in jacketing and buffering will shrink after exposure to elevated temperatures,

which can cause micro bending in the glass fibers and induce excessive loss..

Extended Service Life Test

GR-326-CORE Extended Service Life Test


The most common optical performance measurement

for an optical connector is the Insertion Loss and Return Loss.

Jumper measurement is usually done at the 1310nm and 1550nm

wavelength by using a master jumper and a master adapter. This is

to guarantee the performance measurement consistency. A master

jumper and master adapter are rare products which have near perfect

geometric and loss performance. A master jumper and adapter is

usually used for factory assurance measurement to maintain product

performance consistency. As such, the connector and adapter loss

performance report from the factory is based on a measurement

with a master jumper and adapter. They are usually not used in actual

network deployment due to its high cost and rarity in production. It

is commonly misunderstood that the Insertion Loss and Return Loss

you see tested with a master jumper is what you will be getting in the

actual usage of the product such as in racks, on devices and any other

finished product. The IEC 61753-1 standard was introduced to outline

the Insertion Loss and Return Loss specification based on randomly

mated connectors. The compliance to this standard guarantees the

loss performance of random mated connectors and categorizes it into

4 grades for Insertion Loss and 4 grades for Return Loss. The difference

of a good connector and a bad connector can clearly be differentiated

be measuring the Insertion Loss of a randomly mated connector. It is

known that a connector that has a guaranteed IL of 0.5dB against a

master can increase to as high as 1.00dB or higher in random mating.

The tables below outlines the Insertion Loss and Return Loss grades.

Random Mating Loss Performance

Insertion Loss data against Master

120%

100%

80%

60%

40%

20%

0%

Points where Max IL is reached for each connector brand

GR 326Max IL(0.4dB)

IECMax IL(0.5dB)

Attenuation grade Random Mated Return Loss

Grade 1 ≥ 60 dB (mated) with ≥ 55 dB (unmated)

Grade 2 ≥ 45 dB

Grade 3 ≥ 35 dB

Grade 4 ≥ 28 dB

Attenuation grade Random Mated Insertion Loss

Grade A Not Defined Yet

Grade B≤ 0.12 dB mean ≤ 0.25 dB max for > 97%

of samples

Grade C≤ 0.25 dB mean ≤ 0.5 dB max for > 97%

of samples

Grade D≤ 0.5 dB mean ≤ 1.0 dB max for > 97%

of samples

Random mating Insertion Loss

120%

100%

80%

60%

40%

20%

0%

Points where Max IL is reached for each connector brand

IECGrade A(0.15dB)

IECGrade B(0.25dB)

IECGrade C(0.50dB)

IECGrade D(1.0dB)

SENKO Low Loss

SENKO Premium

SENKO Standard

High quality Competitor

Low quality Competitor


Insertion Loss One of the main advantages of fiber optic networks is the efficient

operational wavelength light transmission suited for long distance

telecommunications. Optical attenuation occurs when the light

intensity reduces as light propagates through an optical network.

Optical attenuation which is also known as Insertion Loss (IL) reduces

the potential transmission distance of an optical network.

Although this can be compensated by the use of higher power

optics, this will introduce a higher deployment cost. In addition, the

use of high power optics can introduce new set of problems such as

increased thermal stress on the optical network, thermal lensing, non-

linear attenuation, and increased requirement for optical hygiene.

Insertion Loss is defined as the ratio of the optical input power over

the optical input power. A representation of IL in decibels (dB) is

shown below:

The largest contributor of attenuation in an optical network are

interconnect components such as connectors and splitters. The

degradation of light intensity is managed through the precise

engineering, manufacturing, quality control and long term reliability

of optical fibers and the interconnect components. The IEC 61300-

3 family of standards outline the basic test and measurement

procedures for fiber optic interconnecting devices and passive

components.

Optical connectors is one of the largest contributors of attenuation.

Fiber optic connectors are an integral part of an optical network to

enable a point of flexibility to alter the network connectivity such

as a cross-connect rack in an exchange. A fiber optic connection is

made up of two connectors which are plugged into an adapter which

aligns the connector ferrules within its sleeves. Attenuation from

connectors arise from multiple factors such as connector cleanliness,

connection gap, core centricity error, angular misalignment and

lateral misalignment.

Connector Testing

Insertion Loss (IL) =

-10 log10 (Po/Pin)where: Po = Output Power Pin = Input Power


Example of a perfect connector termination

• Clean connector endface• Straight joint with good lateral and angular alignment• Fiber core is aligned and in contac

Example of contaminated connector endface

• Contamination on the fiber core can cause high attenuation and even permanent damage if the contamination is burnt by high optical power

• Contamination in between two connectors can cause a gap

• An air gap between the connectors can result in a lower return loss.

Example of connector with angular misalignment

Angular misalignment can be caused by:

• Low quality barrel in the bulkhead adapter or connector ferrule

• Contamination on the side of the ferrule

Example of connector with lateral misalignment

Lateral misalignment can be caused by:

• Low quality barrel in the bulkhead adapter or connector ferrule

• Contamination on the side of the ferrule

Example of core concentricity error

• Position of the fiber core is offset from the actual center of the connector ferrule

• Note: Image is an exaggeration of a core off-set

contamination

connector gap

Actual position of fiber coreCentral position of fiber core

Core Concentricity Error


• Optical Continuous Wave Reflectometer (OCWR)

• Optical Time Domain Reflectometer (OTDR)

• Optical Low Coherence Reflectometry (OLCR)

• Optical Frequency Domain Reflectometry (OFDR)

To ensure the proper performance of an optical transmission system,

various parameters such as attenuation and Optical Return Loss (ORL)

must be within the acceptable tolerance level of the transmission and

receiving equipment. ORL is measured based on components such as

cables, patch cords, pigtails and connectors as well as an end-to-end

network ORL level.

With increasing data speeds and the use of WDM technology, the

measurement of ORL is becoming more important in characterizing

optical networks. ORL is defined as the ratio of light reflected back

from an element in a device, to the light launched into that element.

This is usually represented as a negative number in decibels (dB). The

mathematical formula representing ORL is as shown below:

In addition to the increase in network attenuation, high levels of

reflected optical power can cause light-source signal interference,

higher Bit-Error Rate (BER) in digital systems, lower Signal to Noise

Ratio (SNR), laser output power fluctuations and in more severe

situations, permanent damage to the laser source. ORL and reflectance

must be measured on a component level, such as connector and cable

assembly, and an end-to-end network level.

Higher transmission bandwidth networks requires higher ORL

performance. For example, an OC-48 2.5Gbps transmission network

has a minimum ORL level of 24dB while an OC-768 40Gbps has

a minimum ORL level of 30dB. An FTTx network delivering video

content with a low BER tolerance has a minimum ORL level of 32dB.

As outlined in the IEC 61300-3-6 standard, there are mainly 4 methods

to measure return loss which are:

Return Loss

Return Loss (RL) =

-10 log10 (Pr /Pin)

where: Pr = Reflected Power Pin = Input Power


Rayleigh backscattering is an intrinsic property of optical fiber which

causes light to scatter. This is usually caused by defects and impurities

introduced into the fiber core during the manufacturing process, or

regions of mechanical stress such as microbending. A fraction of the

scattered light which is directed back to the source is detected as ORL

while the majority of scattered light will be lost. Rayleigh scattering

occurs along the total length of fiber.

light Rayleigh scattering

reflected light

light attenuated light

reflected light

air gap

Fresnel backreflection is caused by different network elements

where a transition through different mediums occur. Optical

connectors are usually the highest contributors of reflections due

to air gaps, impurities, geometry misalignments, and manufacturing

imperfections. Common sources of Fresnel backreflection are optical

connectors, mechanical splices, open fiber ends and cracks in the

optical fiber. Significant light is backreflected to the source when

light travels from the fiber core to air. In ORL sensitive networks,

Angle-Polished Connectors (APC) are usually deployed to reduce

backreflection to the source.

The measurement methods are applied depending on the Device under Test (DUT) condition, level of return loss, measurement distance and

the measurement resolution. This paper will focus on the return loss measurement using the OCWR and OTDR methods. Back reflectance is

described as the ratio of reflected optical power to the incident optical power at the input of the device. The term ORL is used to describe the

ratio of relative magnitude of the cumulated back reflectance or multiple Fresnel events and backscattered signal power to the optical power

at the input of the device. There are mainly two factors that cause ORL which are Fresnel backreflection and Rayleigh backscattering.

Causes of Optical Return Loss


Power Meter & Light Source

Limitations

The Power Meter and Light Source works as a pair of devices. As the name suggests, the Light Source is a device that injects a certain amount of

light into the DUT while the Power Meter detects the light power level that comes out of the other end of the DUT. The difference in the power

level provides an accurate representation of the DUT insertion loss.

Unlike the OTDR, the Power Meter & Light Source testing method is unable to discern the individual elements within the DUT. This testing

method can only give the total insertion loss of the DUT.

Depending on the connector quality, the act of mating and demating a connector can result in a different insertion loss level. When measuring

a low attenuation DUT, the connector loss variable can significantly distort the actual insertion loss reading. This limitation can be overcome by

using a method called the cut-back method which maintains the connector termination to the Light Source and Power Meter but it introduces

a fusion splicing which is a new loss element, which has a very low attenuation level if done properly, that is not part of the DUT.

Introduction to Test Equipment

Optical Time domain–Based Measurement (OTdR)

Optical time domain–based measurement spatially evaluates backreflection characteristics both in individual components and along the length

of a fiber. One main instrument that uses this measurement method is the optical time-domain reflectometer (OTDR). An OTDR measures the

backscatter level of the fiber medium itself and the peak reflection level of Fresnel events along an optical link. The backscatter measurement

level is a function of the fiber backscatter coefficient—an intrinsic factor of the fiber under test—and the pulse width used for measurement.

As its name suggests, an OTDR operates in the time domain and measures the backscatter optical-power level from the fiber itself. It enables

users to measure Fresnel backreflection at any point along the fiber under test without de-mating optical interconnections. A light pulse

is introduced into an optical link and will experience both backreflection and Fresnel events along the pathway. The power level of light

reflected back to the source is measured with reference to the time it takes for the light to return to the source. In this way, the OTDR estimates

the distance of an event from the source according to the elapsed time versus the speed of light. This makes the OTDR a very useful tool in

evaluating the distance of the optical network under test as well as the location of components in the network, thus enabling the tester to

evaluate the network for commissioning purposes and locate network faults for maintenance.

There are two types of OTDRs: the photon-counting OTDR (PC-OTDR) and the network OTDR. Although both types of OTDR use the same

principles to measure ORL, the PC-OTDR applies a much shorter optical pulse width, enabling a much higher spatial resolution and reflection

sensitivity. However, this reduced dynamic range lowers the maximum useful DUT length of a PC-ODTR. Due to these differences, the two types

are applied for different purposes: network OTDRs are typically portable and usually deployed in outside plant networks for commissioning

and troubleshooting, while PC-OTDRs are usually used for qualification and troubleshooting of individual components, modules, or subsystems

in which reflections are often closely spaced.

Max Spatial Resolution

Reflection Sensitivity

Reflectance Measurement

Range

Optical Pulse Length

Max Length of dUT

NetworkOTdR

> 1 m −60 dB ≈ 50 dB ≥ 10 ns < 100 km

PC-OTdR ≈ 10 mm < −120 dB ≈ 60 dB ≤ 10 ns < 200 m


Backscatter Coefficient SettingsAs OTDRs measure backreflection power levels, the reflectance of a given element in the DUT depends on the fiber backscatter coefficient,

optical pulse width, and the measured reflectance amplitude with reference to the backscatter level. An inaccurate backscatter coefficient value

setting can lead to an error in measuring reflection level. The percentage of measurement uncertainty increases with a lower reflectance value.

The backscatter coefficient is usually one of the parameters that is set when performing an OTDR measurement. In a fiber-access network,

especially one that has legacy fibers, there may be a combination of various fiber standards – for example from early G652.A fiber to G657.A2

fiber – as well as fiber from different suppliers manufactured with different methods, such as the plasma chemical vapor deposition (PCVD)

method or the modified chemical vapor deposition (MCVD) process. The OTDR’s backscatter coefficient setting cannot be adjusted to match

the varying fiber characteristics in the network under test.

Index of Refraction (IOR)IOR is a way to measure the speed of light in a medium with reference to the speed of light in a vacuum, where light moves fastest. Light travels

at approximately 3 x 108 ms−1 in a vacuum. The IOR of a medium such as an optical fiber core is calculated by dividing the speed of light in a

vacuum by the speed of light in the medium. By definition, the IOR of light in a vacuum is denoted by 1. A typical single-mode fiber has a silica-

doped core with an IOR of approximately 1.447. The larger a medium’s IOR value, the more slowly light travels in that medium.

An inaccurate IOR setting in an OTDR will cause the total distance of the network measured to be skewed. If the IOR is set too high, the OTDR

will calculate the network distance to be shorter than it actually is; likewise, if the IOR is set too low, the OTDR will measure too long a distance.

A difference in IOR setting of just 0.01 can cause a reading difference of 70 m over a 10 km fiber span. When an OTDR is used to locate a specific

fault in a network, an incorrect IOR setting can cause the fault location shown in the OTDR to be far off from the actual location.

Limitations

Mode Field diameter (MFd) Mismatch The MFD of an optical fiber is the area where light propagates. This

area is usually slightly larger than the fiber core as a portion of

light propagates through the cladding as well. When two optical

fibers with different fiber core size and MFD size are spliced, the

attenuation measurement by using an OTDR can result in a gainer or

an exaggerated loss. This is due to the propagation of light through

mediums with different Index of Reflection.

The attenuation reading from the OTDR depends on the difference

in fiber MFD and the measurement direction of the OTDR. If the

OTDR measurement is made from a fiber with a larger MFD to a fiber

with a smaller MFD, the reading will result in a gainer. However, if the

measurement is made from a fiber with a smaller MFD to a fiber with

a larger MFD, the reading will result in an exaggerated loss.

core

core

core

core

cladding

cladding

OTDR measurement results in an exaggerated loss

OTDR measurement results in a gainer

Backreflection reduced after splice point due to MFd mismatch

Backreflection increased at splice point due to MFd mismatch

cladding

cladding


dead ZoneA dead zone is the location of a section of network beyond a reflective event, where

subsequent network characteristics cannot be measured. There are two types of dead

zones: attenuation dead zones (ADZs) and event dead zones (EDZs).

An ADZ is the minimum distance required to make an attenuation measurement for

an event. This value is usually defined as the distance between the rising edge of a

reflective event to the 0.5 dB deviation from a straight line fit to the optical backscatter

level. The optical backscatter level is the sloping line that indicates the fiber attenuation

over distance.

An EDZ is the minimum distance required for the OTDR to detect two separate events.

This is usually defined as the distance between two cursor points set at 1.5 dB below a

reflective peak, where the peak is non-saturating.

Dead zone measurement depends on the pulse width and the network element

reflectance level. A shorter pulse width will result in a shorter dead zone, while a

connector with a high return loss will result in a longer dead zone. When testing a long-

distance network, testers will use a higher pulse width, thus increasing the length of the

dead zone. This can cause multiple nearby events to be identified as a single merged

event. Examples include the connector and splice of a pigtail as well as both connector

ends of a patch cord.

Most OTDR manufacturers specify the OTDR dead zone for the shortest pulse width

and optimal connector reflectance. However, this specification cannot be taken at face

value. The suitable pulse width to be used for network measurement usually depends

on the total length of the network, while individual components within the network

have variable reflectance performance due to manufacturing quality and hygiene.

Helix FactorOTDRs are widely deployed in testing and measurement of outside-plant optical fiber

networks. In an outside-plant environment, optical fibers are deployed in cables. The

most common cable types deployed are loose-tube cables and slotted-core cables.

Optical fibers within these cables are not strung in a straight line but spiral around a

central strength member in an “SZ” fashion within loose tubes.

As light from an OTDR travels through the optical fiber, OTDRs measure the optical fiber

distance rather than the cable distance. Depending on the helix factor of a cable—

which can range from 0.3% to 42%, depending on the cable design—a cable 700 m

long may comprise 1,000 m of fiber distance. Without an accurate measurement of the

helix factor, fault locating by using an OTDR may result in considerable discrepancy.

Most modern OTDRs have a helix setting to adjust the distance measurement.

attenuation deadzone definition

Event deadzone definition

attenuation deadzones of two concatenated connectors

attenuation deadzones of two concatenated connectors

Applies to non-saturating peak (good UPC connector)

0.5 dB deviation from straight line backscatter

ADZ

Applies to non-saturating peak (good UPC connector)

EDZ

1.5 dB below peak

Can’t measure OkayADZ-1 ADZ-1

Can’t measure OkayADZ-1 ADZ-1


Optical Continuous Wave-Based Measurement (OCWR)

OCWR relies on a basic power-meter measurement of the launch power (assuming no DUT) as a base reference and compares this to the optical

power reflected back to the source. For a backreflection meter, this method is usually used to measure the ORL of patch cords. For an Optical

Line Test Set (OLTS), this method can be used to measure the total ORL and attenuation of a network.

The OCWR method cannot differentiate between Rayleigh backscatter and Fresnel backreflection. If a patch cord tested with a backreflection

meter yields a low ORL result, it is highly likely that the connector is faulty—although there is a possibility that the cord itself has been

manufactured with microbends. When using test instruments that employ the OCWR method, the network or component under test must be

isolated from the rest of the optical network to prevent any backscatter or reflection from events further down the link. This means that the

OCWR method cannot be deployed on a live network.

To isolate the DUT from unwanted reflections, the optical fiber must be terminated at two different points. The two commonly used termination

methods are the mandrel wrap and the index-matching gel or block. Each of these methods have limitations, as shown in the table below. The

difference in backreflection between the two termination points is calculated to give the DUT backreflection level.

Multimode fiber cannot be terminated effectively using mandrel wraps, as the wraps can introduce bend loss but not totally terminate the fiber.

In most cases, the use of an index-matching gel or block is the only solution. An index-matching gel or block matches the IOR of fiber, which

causes light to diffuse out of the fiber core rather than experience Fresnel backreflection. However, index-matching gels are not as effective

as mandrel wraps, and they can never fully prevent backreflection. Multiple measurements are usually required, with the highest return loss

measurement result taken as an approximation of the potential result if a mandrel wrap is used.

Limitations

Mandrel Wrap Index-Matching Gel Index Matching Block

Not applicable to non-bendable structures such as hardened cables or cords

Matching gel might leave a residue on the polished connector end face

Not suitable for connectors with guide pins, such as MPOs, or where the connector end-

face is not accessible, such as E2000.

Bend-insensitive fiber does not exhibitbend loss

Backscatter of the fiber length between the reflective eventand the far end of the cable might amplify reflections

Cannot optically isolate far endthrough bending.

Limited effectiveness in terminating reflections

Manual process to isolate far end and highly depends on the technician’s skill level


Testing Procedure

OCWR relies on a basic power-meter measurement of the launch power (assuming no DUT) as a base reference and compares this to the optical

power reflected back to the source. For a backreflection meter, this method is usually used to measure the ORL of patch cords. For an Optical

Line Test Set (OLTS), this method can be used to measure the total ORL and attenuation of a network.

In the cut-back method is the most accurate insertion loss measurement for a Device under Test (DUT). This method is usually used for

component testing in a lab situation. The DUT is connected to a light source with a temporary joint which is usually an optical splice. The output

of the DUT is then connected to a power meter. The power level measurement is noted as P1.

The temporary joint is cut and then spliced to the fiber connected to the power meter. The power level measurement is noted as P0. The optical

attenuation of the DUT can then be calculated as P0 – P1.

The substitution method is usually used for component testing where the input and output of the DUT are connectorised. The DUT is connected

to a light source by terminating the DUT input connector to a reference adapter. Similarly, the output of the DUT terminated to a power meter

by using a reference adapter. The power level measurement is noted as P1.

The input and output connectors of the DUT are disconnected and substituted by a patch cord. To achieve a higher DUT attenuation

measurement accuracy, a master patch cord with low loss connectors can be used. The power level measurement is noted as P0. The optical

attenuation of the DUT can then be calculated as P0 – P1.

Cut-back Method

Substitution Method

Insertion Loss Measurement with Power Meter & Light Source

Power Meter

Temporary joint

Temporary joint

dUT

dUT

Light Source

Temporary joint

Temporary joint

Power MeterLight Source


The insertion method is usually used to measure a connection attenuation performance such as a splice point, or a field-mountable connector.

The light source and power meter is directly connected and the power level measurement is noted as P0.

The connection between the light source and the power meter is then cut. The cut fiber is then spliced to re-establish the optical network with

a higher attenuation which is measured and noted as P1. The optical attenuation of the DUT, which in this scenario is a splice point, can then

be calculated as P0 – P1.

An OTDR is not an ideal equipment to measure optical attenuation as it only detects back reflection level at different locations in the optical

network instead of measuring the actual optical output power with respect to the input power. As outlined in a previous section, if two fibers

with different specification are spliced, the MFD mismatch may cause a skewed attenuation reading called a gainer and exaggerated loss. The

gainer and exaggerated loss reading can be corrected by performing a bidirectional OTDR test and getting the average attenuation reading

of the splice event.

Insertion Method

Insertion Loss Measurement with OTdR

Power Meter

Temporary joint

Temporary joint

Light Source

SPLICE or CONNECTOR

Insertion Loss =

a + b

2

IL Excessive Loss

a

gainer

b


5.4.2. Return Loss Measurement with OTdR Return Loss Measurement with OTdR

A launch lead, which is a standard patch cord with suitable connectors

on both ends, must be used to connect the OTDR to the DUT. This

ensures that the first event in the DUT can be quantified. If a launch

lead is not used, the high reflection from the OTDR internal connector

masks the actual reflectance and attenuation of the DUT.

The correct parameters suitable for the measurement of the DUT is

set in the OTDR. These parameters include the IOR, backscatter, helix

factor, pulse width, measurement distance, and acquisition time. The

importance of an accurate IOR, backscatter and helix factor settings

is outlined in the previous section. Other important settings are::

• Pulse width: Smaller pulse width has a higher measurement

resolution but has limited distance and vice versa.

• Measurement distance: To be set as closest to the actual network

distance. If set to be lower, the far end of the network is not tested.

If set to be too high, the resolution of the network under test will

be low.

• Acquisition time: Test result with low acquisition time will result

in higher noise level. However, longer acquisition time will require

longer man hours for testing purposes

If the optical network parameters are not know, most modern OTDR

have auto settings. The OTDR tests the network starting with a short

pulse width and incrementally increases the pulse width until it

detects an end-of-fiber reading. The OTDR automatically adjusts the

pulse width and measurement distance setting which best suits the

DUT conditions.

An OTDR trace will be produced to indicate the detected events in the

DUT. There may be discrepancies between the OTDR trace result and

the actual components in the DUT, this may be due to:

• High quality connectors with low reflectance is recognized as a

splice rather than a connector.

• Undetected events such as low attenuation splices.

In PON systems where splitters are installed in the OSP, the use of a

short pulse width, such as a 5ns pulse width, will not be able produce

a readable result after the splitter due to the high loss. A 1:16 splitter

will cause about a 14dB attenuation. This will usually cause the OTDR

trace to drop below the OTDR noise floor. However, using a larger pulse

width such as 275ns will cause result in a lower resolution reading

before the splitter, thus potentially missing events or merging closely

spaced events.

One possible method to test such a network is by using a short pulse

width, such as 5ns to 10ns, to identify all event locations up to the

splitter. A second test is performed by using a medium pulse width,

such as 50ns to 100ns, for increased dynamic range to measure splitter

loss while maintaining good resolution. The third test is performed

by a longer pulse width, such as 275ns or higher, to test past the

splitter to the end of the network. Further tests may be required if the

dynamic range is insufficient to get a noise-floor margin of at least

6dB. Information from the multiple OTDR traces must be analyzed

and tabulated into a report. Such testing requires skill and time. In

addition, tests are usually performed using the 1310nm and 1550nm

wavelength to detect macrobends, which results in longer test times.

OTdR dUTLaunch Lead

OTdR

Launch LeadConnector

SpliceReceive End


Return Loss Measurement with OCWR

A reference patch cord is terminated to the light source of the OCWR.

The end of the reference patch cord is coiled around a mandrel to

increase attenuation and prevent Fresnel backreflection from the

open end connector from being detected. The mandrel is applied as

close to the end connector as possible. The detected ORL is set as a

base reference.

A DUT is then connected to the reference patch cord. The DUT is

then coiled around a mandrel as close to the connection point as

possible. This reduces the optical fiber backscatter from affecting the

connector reflectance reading. The OCWR displays the ORL of the DUT

with respect to the base reference value.

A master patch cord is usually used as the reference patch cord. A

master patch cord is manufactured with very strict quality standards

to ensure repeatability of measurement result regardless of the test

equipment type, manufacturer, the operator or the period of test.

The connector interface of the master patch cord has near perfect

specification on the end face radius of curvature, apex offset and fiber

protrusion/undercut. ORL of Patch Cord under test = ORL B - ORL A

OCWR

Reference Patch Cord

ORL B

Patch Cord under test

Mandrel

ORL B

dUT

ORL A

OCWR

Reference Patch Cord

ORL A

Mandrel

BR = -58.0db

Backreflection Meter

FC/APC

BR

BR0

Termination Point

for BRTOTAL

Termination Point

for BR0

Measurement Jumper

BRDUT

DARK

I

O

POWER

(LOCAL)

1310149015501625

DUT


OverviewOne of the drivers of many network operators to deploy optical

fiber has been, of course, its performance & reliability. Although

the general maintenance requirement is greatly reduced, many

network operators around the world is finding one main component

in an optical fiber network to be the cause of network failures.

That component is the optical connector, the ‘weakest link’ of your

network. Based on a study conducted by NTT Advanced Technology,

4 of the top 5 causes of network faults are connector related and the

No.1 cause is contaminated connector end faces. The same problem

is reported by major optical fiber network operators in Asia with the

lack of appreciation for fiber cleanliness accounting for 90% of all

reported faults.

In the past, connector contamination in optical transport networks

or data center fiber interconnect networks were less prevalent due to

the controlled environment of exchanges or data centers. However,

with the increasing deployment of optical fiber outside plant

networks, optical connectors are widely used in outdoor enclosures

such as roadside cabinets and pedestals as well as in customer

premise termination points that do not have filters to reduce dust

contamination or environment control systems to reduce humidity.

Although connector contamination is common, it can be easily

rectified. The main area of an optical connector that must be cleaned

is the ferrule endface.

Connector Hygiene

Contamination of the connector End Face

Poor polishing of the ferrule

Mistakes attaching lables to the cable

Damage of the optical connector

Damage of the ferrule End Face

Connector End Face contamination is the N°1 cause of network faults

1st

2nd

3rd

4th

5th

!


The ferrule is the most essential part of the connector which holds

and centers the optical fiber for connection with another section of

a fiber network. As defined in IEC 61300-3-35, an optical connector

end face is separated into three zones which are the Core (Zone A)

where light travels, Cladding (Zone B) which is the outer section of the

Core which reflects light back into the Core, and the Buffer Coating

(Zone C) which protects the optical fiber from moisture or damage

from external forces.

The core of a single mode connector is only 9µm. A piece of dirt,

speck of dust or oil smudge in the right position may cause high

reflection, insertion loss and fiber damage. Connector cleanliness is

critical in high power transmission systems such as DWDM systems

or long haul transmission where Raman amplifiers are used, the

optical signal transmission power may be up 1W to 5W. In a single

mode fiber transmission, such high power transmission may burn the

contaminant and fuse the dirt with the silica material of the optical

fiber, thus requiring the replacement of the connector.

The source of contamination is usually due to connector mishandling

and a lack of understanding for optical hygiene. Some of the most

common mistake for contaminating optical connectors are:

Image above: example of bad practice

• Leaving a connector uncapped for even a short period of time where it will be prone to dust contamination.

• Touching the connector end face with fingers thus leaving skin oil or passing on dirt

• Using unsuitable cleaning methods or products such as toilet paper, water or even shirt sleeves

• Assuming that connectors which are protected by dust caps are clean or factory guarantee cleaned

• Not cleaning both connector end faces before making a connection.

Optical Connector Ferrule & Contamination

Clean connection

Dirty connection


The ‘IEC-61300-3-35: Fiber optic interconnecting devices and passive

components - Basic test and measurement procedures - Part 3-35:

Examinations and measurements - Visual inspection of fiber optic

connectors and fiber-stub transceivers’ sets the standards on

measurement methods, procedure to assess the connector end face

and determines the threshold for allowable surface defects such

as scratches, pits and debris which may affect optical performance

and it is the de facto standard for the fiber optics industry globally.

According to the standards document, there are three inspection

methods which are the:

• direct view optical microscopy

• Video microscopy

• Automated analysis microscopy

The Direct view optical microscopy is essentially a microscope

designed to view optical connector end faces. Although most of

such microscopes have an optical filter to prevent eye damage

from exposure to transmission lasers, many network operators

do not approve its use due to health and safety reasons. Another

disadvantage of this method is different microscopes need to be

used for inspecting a connector or a connector terminated onto a

bulkhead adapter.

Video microscopy uses an optical microscope which projects an

image onto a display screen thus preventing any direct exposure

to transmitting lasers. An example of a video microscopy is a

Fiber Inspection Probe (FIP) with a display unit. Most FIPs available

in the market have interchangeable tips to inspect bare connectors

or when it is terminated onto a bulkhead adapter. There are also tips

available for different connector types.

The Automated analysis microscopy is similar to the video

microscopy but with an added feature which uses an algorithmic

process to automatically analyze the connector hygiene based on a

set criteria. This analysis provides a “Pass” or “Fail” result, thus removing

any human assessment ambiguity.

Inspection Standards

Fiber microscope

Fiber Inspection Probe (FIP)

Automated analysis microscopy


There are two assessment procedures outlined in IEC-61300-3-35 for a single fiber ferrule such as an SC or LC connector and for a multi-fiber rectangular ferrule such as the MPO connector. The end face of the connectors are divided into measurement regions starting from the center of the core and moving outwards.The tables below outline the measurement regions:

Zone Diameter for single mode Diameter for multimode

A: Core 0 µm to 25 µm 0 µm to 65 µm

B: Cladding 25 µm to 120 µm 65 µm to 120 µm

C: Adhesive 120 µm to 130 µm 120 µm to 130 µm

D: Contact 130 µm to 250 µm 130 µm to 250 µm

Note 1: All data above assumes a 125 µm cladding diameter.Note 2: Multimode core zone diameter is set at 65 µm to accommodate all common core sizes in a practical manner.Note 3: A defect is defined as existing entirely within the inner-most zone which it touches.

Measurement regions forsingle fiber connector

Zone Diameter for single mode Diameter for multimode

A: Core 0 µm to 25 µm 0 µm to 65 µm

B: Cladding 25 µm to 115 µm 65 µm to 115 µm

Note 1: All data above assumes a 125 µm cladding diameter.Note 2: Multimode core zone diameter is set at 65 µm to accommodate all common core sizes in a practical manner.Note 3: A defect is defined as existing entirely within the inner-most zone which it touches.Note 4: Criteria should be applied to all fibers in the array for functionality of any fibers in the array.

Measurement region formulti-fiber rectangular connector

The IEC-61300-3-35 standard outlines the Pass/Fail threshold level for the visual requirements for the different connector types. These criteria are designed to guarantee a common level of connector condition for connector performance level measurement. Based on the zones of a connector, the standard outlines the allowable number of scratches as well as the size and number of defects. There are four main requirements outlined which are:

• Visual requirements for PC polished connectors, single mode fiber, RL ≥ 45dB

• Visual requirements for angle polished connectors (APC), single mode fiber

• Visual requirements for PC polished connectors, single mode fiber, RL ≥ 26dB

• Visual requirements for PC polished connectors, multimode fibers

ABCD

Zone Scratches Defects

A: Core ≤ 4 None

B: Cladding No limit No limit < 2 µm / 5 from 2 µm to 5 µm / None > 5 µm

C: Adhesive No limit No limit

D: Contact No limit None ≥ 10 µm

The table below outlines the visual requirements for a single mode angle polished connector:


The race to deploy broadband FTTx networks is resulting in a global

fiber technician skill shortage. It is easy to train a technician to perform

a connector hygiene test but experience in operating and maintaining

a fiber network is required to be able to make correct assessments.

The use of automated techniques de-skill and reduce the risk of poor

installation. An automatic Pass/Fail analysis function based on the

IEC-61300-3-35. In addition, Geo tagging features together with cloud

storage allow centralized review by fewer highly skilled technicians

and confirmation that procedures were correctly carried out:

• Prevent any error with a standardized and impartial assessment

• Increase productivity by speeding up the assessment process through set algorithm

• Avoid replacement of connectors with slight defects that do not adversely affect performance

• Ensuring excellent long term connectivity performance

• Confidence correct process has been carried out

To cater for the massive adoption of FTTH services, the cost of

setting up all the field technician is highly expensive especially with

the various tools and equipment required to perform their tasks

effectively. The common connector hygiene inspection tool consists

of an FIP and a monitor to view the connector end face. The monitor

may be a standalone unit for the FIP, a different test equipment with

a monitor such as an Optical Time Domain Reflectometer (OTDR) or a

laptop. The high cost of these equipment becomes a barrier to entry

for many fiber technicians or contracting companies and in many

cases, proper inspection is not conducted. Hence, a low cost and high

performance alternative is needed to cater for the market.

The cost effective SENKO Smart Probe is one of these cost effective

alternative which allows relatively low skilled technicians to inspect

the fiber end faces and stream the images to any laptop, tablet or

smartphone. Many technicians already carry smartphones or tablets

as part of their daily operations hence no additional display device is

required and the SENKO Smart Probe connect to the smart devices via

conventional Wi-Fi.

In order to keep a record of connector inspection, all test results can be

uploaded into a cloud repository for future references or for reporting

purposes. These uploaded records with their associated location

data give skilled technicians the opportunity to review the hygiene

of individual connectors and provide network operators with the

confidence that proper procedures have been correctly carried out.

Inspection Tools


Inspection Tools for MPO Connectors

· For SM & MM MPO (up to 24F)

· High precision alignment

· Available in APC and PC version

Visualization of MT 12 fiber connector end face(two fibers of MT 12 fiber connector)

The race to deploy Connector inspection for MPO is much more

complicated. With current standard Fiber Inspection Probe (FIP) for

MPO connectors, the inspection of a single ferrule with multiple

connectors requires the operator to focus on one single fiber at a

time. The FIP fiber tip comes with a dial which moves the focus from

fiber to fiber.

The inspection is tedious and time consuming. In addition, multi-

fiber inspection probes the boundaries between Zone C and Zone

D is usually not visible to enable proper connector evaluation. Due

to the limited magnification, automated qualification for the MPO

connector inspection is not available.

The SENKO MPO FIP can inspect all fiber endface at once. The entire

connector endface needs to be cleaned even if only one fibre is

contaminated.

MPO Tip Up to 24F Available


Optical cleaning tools are specialized tools which are used to remove contaminants from optical connectors and bulk heads. There are two types of cleaning methods namely the dry cleaning and wet cleaning. The standard document, ‘IEC 62627-01: Fibre optic interconnecting devices and passive components - Technical Report - Part 01: Fibre optic connector cleaning methods’ describes a comprehensive cleaning methodology and is usually adopted as the industry’s best practice.Dry cleaning is the most common and fastest cleaning method which is used in connector manufacturing plants and in the field. The drawback of the dry method is the risk of potentially scratching the end face if there are any hard particles on the connector surface. In addition, some dry cleaners cause electro static charges on the

connector end face which attracts dust particles. The dry method usually cleans the majority of connectors, however, in more severe cases of contamination, the wet method is more effective. The main advantage of the wet cleaning method is the active solvent used in the cleaner which acts as a solvent for oils, raises particles to prevent connector end face damage, removes moisture and is fast drying. The most common solvent used in the market is 99.9% isopropyl alcohol (IPA). The presence of a solvent prevents the buildup of electrostatic charge on the connector end face. However, the excessive use of solvents may cause the contaminants to be pushed to a side of the ferrule and slowly creep back into center after the connector has been inspected and terminated. To prevent such an occurrence, a final dry cleaning is performed after a wet clean.

Cleaning Tools

Lint Free Swabs

Lint free swabs can be used to clean the internal barrel of a bulkhead adapter or the connector end face which is terminated in a bulkhead adapter.

If sufficiently large, contaminant on the side of the internal barrel may cause misalignment of two connectors thus increasing the connector insertion loss.

Lint Free Wipes

Lint free wipes are not usually used to clean connector end face. The operation of wiping the connector end face with a lint free wipe requires delicate skill to avoid damaging the connector end face.

Cartridge Cleaners

A small window is opened to expose the cleaning cloth when the lever is pressed. This will also turn the cleaning cloth so that a clean cloth section is used for every clean. The connector end face is pressed and wiped against the cloth. For a more effective clean, specially treated cleaning cloth that prevents electrostatic charge buildup can be used.

Pen Cleaner

Pen cleaners have a reel of cleaning cloth that rotates at the tip of the cleaner when it is pressed against a connector in a bulk head adapter or directly onto a connector if a fitting is placed onto the tip. This instrument with a “push and click” mechanism cleans the ferrule end faces removing dust, oil and other debris without nicking or scratching the end face. There are mainly three types of pen cleaners suitable for 2.5mm, 1.25mm and MPO connectors.

Adhesive BackedCleaner

Adhesive backed cleaners have a sticky tip with a soft backing at the top of the cleaner. This cleaner is pressed onto the end face of a bare connector or when terminated in a bulkhead adapter. The soft adhesive removed dust and other particles.

Compressed Air

Compressed air or air duster is used to blow air through the nozzle to get rid of dust on the connector end face. To maintain purity and pressure in the canned air, special material such as difluoroethane or trifluoroethane is used. It is advisable to select a material which has a lower Global Warming Potential (GWP) index.

The following table outlines the most common dry cleaning tools and the area of use:


Wet cleaning is usually done by applying 99.9% isopropyl

alcohol to any of the dry cleaner type in situations when

contamination on connectors is unable to be cleared from dry cleaning

alone. This usually occurs when contaminant on a connector end face

is left uncleaned for a long period of time. Multiple wet cleaning may

be required to fully clean a connector end face and must always be

followed by a final dry clean to remove isopropyl alcohol residue.

There is currently no industry standard on the number of iterations

one should attempt to clean the connector end face before disposing

it but the common practice is generally 3 times. Nevertheless, an

internal guideline should be set in order to avoid wasting time and

resources trying to clean a contaminated/damaged connector. The

diagram below summarizes the recommended cleaning procedure.

Inspect endface with fibre scope

Dry Clean

Dry Clean


Wet clean immediately

followed by Dry clean



Plug into clean mating connector




is endface clean?

is endface clean?

is endface clean?

is endface clean?

YES

YES

YES

YES

NO

NO

NO

NO

START


Cleaning Challenges for MPO Connectors

Unlike single fiber connectors, the cleanliness of the total surface of

a multi-fiber connector such as the MPO connector is also critical to

making a proper connection. The array of fibers is presented on a flat

surface which comes into contact when terminated. Any contaminant

around the optical fibers and alignment pin prevents full contact

of the two connectors. This creates an air space which reduces the

connector loss performance. Conventional MPO cleaning tools such

as the pen cleaner clears contaminants around the optical fiber array.

However the space around the alignment pins remains contaminated.

A new type of MPO cleaning tool such as the SENKO Smart Cleaner

Stick is able to effectively remove oil, dust and dirt particulate from

pin to pin on the connector endface. An MPO connector is pushed

onto the cleaner which sticks onto any contaminant, thus removing

any particulate when the connector is removed.

Step 2:PUSH MT Ferrule against the stick surface for cleaner

Step 3:Remove the MT Ferrule, dirt and oil will be transferred from the ferrule to the cleaner

2 3Step 1:Sticker cleaner contains 10 “Stick” cleaning area

1

Conventional cleaner cleaning area

Particles around the pin area can remain which could cause “air gap.”

Full surface will be cleaned

NEW “Stick” Cleaner Cleaning Zone will clean the full end face


IEC Connector type

There are many types of connectors specified under the IEC 61754 family of standards. Such standardization enables a more widespread use of

the connectors through a more diverse manufacturers, connector interoperability and connector quality assurance. The list of connectors that

are currently specified under the IEC standard is as follows:

1 IEC 61754-2 BOFC Connector

2 IEC 61754-3 LSA Connector

3 IEC 61754-4 SC Connector

4 IEC 61754-5 MT Connector

5 IEC 61754-6 MU Connector

6 IEC 61754-7 MPO Connector

7 IEC 61754-8 CF08 Connector

8 IEC 61754-9 dS Connector

9 IEC 61754-10 Mini MPO Connector

10 IEC 61754-12 FS Connector

11 IEC 61754-13 FC-PC Connector

12 IEC 61754-15 LSH Connector

13 IEC 61754-16 PN Connector

14 IEC 61754-18 MT-RJ Connector

15 IEC 61754-19 Sg Connector

16 IEC 61754-20 LC Connector

17 IEC 61754-21 SMI Connector

18 IEC 61754-22 F-SMA Connector

19 IEC 61754-23 LX.5 Connector

20 IEC 61754-24 SC-RJ Connector

21 IEC 61754-25 RAO Connector

22 IEC 61754-26 SF Connector

23 IEC 61754-27 M12 Connector

24 IEC 61754-28 LF3 Connector

25 IEC 61754-29 BLINK Connector

26 IEC 61754-30 CLIK! Connector

27 IEC 61754-31 N-FO Connector

28 IEC 61754-32 diaLink Connector

29 IEC 61754-34 URM Connector


IEC 61754-2 BOFC Connector

IEC 61754-3LSA Connector

The Bayonet Optical Fiber Connector (BOFC) is also more commonly

known as the Straight Tip (ST) Connector. The ST Connector was

developed by AT&T as a connector which deploys a plug and socket

design. This was the first defector standard for fiber optic cabling and

was widely deployed for networking applications in the late 80s and

early 90s.

The connector has a cylindrical shape connector with a 2.5mm

keyed ferrule. The connector and matching adapter has a latch

which requires a half-twist bayonet to lock and unlock the connector

termination. The ST connector is spring loaded to enable an effortless

mating and demating operation.

The main application for the ST connector are in CATV networks, LAN

and measurement equipment. The popularity of the ST connector is

soon overtaken by the FC connector which uses the same twist lock

mechanism but with a more compact design.

The DIN connector was originally standardized by the Deutsches

Institut für Normung (DIN), a German national standards organization.

The term “DIN connector” usually refers to a family of round connectors

that is usually used for electrical connectivity such as computing data,

video and audio. Due to the wide range, the document number of the

DIN connector standard is also mentioned to discern specific types of

connectors. The optical fiber connector based on the DIN standard is

DIN 47256 or also known as the LSA connector.

The connector body is similar to the more known FC connector with

a screw on connector body. However, the ferrule is much larger. This

causes the connector to be much more expensive.

aDvaNTaGES DISaDvaNTaGES

Proven reliability Expensive ferrule design

Compact connector design

ST Connector

DIN Connectors


Easy mating and dematingdue to spring loaded design

Locking mechanism can be misaligned and result in amisaligned ferrule terminationwhich results in high loss

39.1

39.2


IEC 61754-4SC Connector

The Subscriber Connector or more commonly known as the SC

connector is designed by NTT, a Japanese telecommunications

company, as an improvement over the FC connector. The SC connector

is a push/pull type connector which enables a more compact patch

panel where traditional FC connectors require additional operation

space to screw and unscrew the connector locking mechanism. In

addition, the SC connector push/pull mechanism reduces the time to

terminate connectors.

The SC connector has a fully plastic body which is cheaper to

manufacture with a moulding compared to machining metallic

connectors. The ferrule size of the SC remains the same as the FC

connector with a 2.5mm ferrule.

With increasing deployment of SC connectors in the fiber access

network such as FTTH saw the introduction of field installable

connectors. There are multiple types of SC connectors where the

most common types are designed to be compatible with 250µm fiber,

900µm fiber, fiber cords as well as direct termination to the ends of

cables such as the hardened SENKO IP Connector.

With increasing deployment in network exchange and data centers,

field splice-on connectors are introduced. This is an improvement

on the connector return loss compared to standard field installable

connectors which employs a mechanical splice within the connector

body.

Developments in customer premises fiber termination saw the

improvement of network reliability and safety. The auto-shuttered

SC connector and adapter were introduced to prevent accidental eye

injury from looking directly into an optical connector by users who

have no understanding of optical networks and its safety aspect.


Highly popular connector worldwide and for most application

Large connector footprint compared to LC connectors

Simple Push/Pull connector operation

Compatible with both single mode and multimode fiber

Available for field installable connector for various fiber and cable sizes

IP-SC Connector

SC 900um Standard Connector

2.0mm Long Boot

3.0mm Long Boot

SC SHUTTERED Connector

39.3


IEC 61754-5MT Connector

The Mechanical Transfer (MT) Connector was first introduced by NTT in

1988 as the first multi-fiber termination connector that can terminate

up to eight fiber cores in one single connection. The connector

design enables an 8-fiber ribbon can be terminated into a single MT

connector which has a 7mm width and 3mm height footprint. Further

development of the MT connector saw the introduction of higher

density designs which enables up to 48 fiber core terminations in a

single connector.

The MT connector has a male and female design. The male connector

has two guide pins while the female connector has two holes where

the guide pins are slotted into to align the connector. When the

male and female connectors are terminated, a spring loaded clip is

then used to hold the connectors together. To avoid damaging the

connector guide pins, a special MT connector tool is required to

remove the spring loaded clip to demate the connector.

Field assembly MT connectors were also introduced for the termination

of up to 12-fiber ribbon. However, the operation to assemble the MT

connectors requires high precision alignment to obtain a low loss

connector for all 12 fiber cores. In addition, the assembly requires the

use of a magnifier as well as a two-part epoxy to hold the fiber in place.


First introduction of a high fiber count connector

Fiber connection is done on a ferrule termination which has less protection compared to connectors with an body

Small form factor for high fiber count termination

Requires a special tool to demate

39.4

Source: Kyoei High Opt


MU with 2.0mm Cable Boot

MU with 1.0mm Fiber Short Boot

MU with 1.0mm Fiber Boot

IEC 61754-6MU Connector

The Miniature Unit or better known as the MU connector is designed

by Nippon Telegraph and Telephone (NTT) cooperation and is very

popular in Japan. The use of MU connectors outside of Japan is very

limited. Similar to the LC connector, the MU connector is a Small Form

Factor (SFF) connector with a 1.25mm ferrule. The MU connector

looks like an SC connector but at half the size. The connector uses a

push/pull locking mechanism similar to the SC connector and the MU

connector is sometimes referred to as a mini-SC.

The connector features a pre-assembled body and precision molded

plastic housing, and a free-floating ferrule held in place with a

precision spring. MU connectors are widely used in active device

termination, premise installations and telecommunication networks

such as FTTH, LAN and WAN.

For a patch panel or similar type application, the MU-J type connector

is also available. The MU-J is essentially an MU connector without the

housing. Together with a short boot, the MU-J type connector is ideal

for back panel and high density situations. The MU-J connector is

fully compatible with the MU connector when used with a suitable

bulkhead adapter.


Small Form Factor which is effectively half the size of an SC connector

Not widely application outside of Japan

Push/pull locking mechanism makes it easy to operate

39.5


IEC 61754-7MPO Connector

The MPO connector was first introduced by NTT in the 1990’s as a

solution to a growing FTTH fiber access network. The connector is

based on the MT ferrule technology introduced in 1985 by NTT that

was also used in the MT-RJ connector. The MT-RJ has only two fibers

with a 750µm pitch within the ferrule, however MPO connectors can

have an MT ferrule with a fiber count ranging from 4 to 72 fibers. The

MT ferrule is typically manufactured by using Polyphenylene Sulfide,

which is a glass filled engineering polymer which has a thermal

stability very close to glass. While there are many MT ferrule based

connectors, the MPO is the most common.

The MPO connector has a similar footprint as an SC connector at

82mm2, however the MPO has a rectangular shape instead of square.

Comparing an SC connector with a 72-fiber MPO connector, the fiber

density of the MPO connector is 1.3mm2 per fiber. This is 63 times the

density of an SC connector.

The MPO is separated into a male and female connector. The male

connector has two guide pins that slots into two holes of the female

connector within the MPO adapter to align the ferrules for connector

termination. As a general practice, the male connector is usually

terminated in the patching back panel, wall outlets or transceivers

while the female connector is used at the ends of jumper cords. This

practice is to set the male connectors in a static position to protect the

guide pins from accidental damage.

MPO Male Connector

Key Up Key Down

MPO Female Connector

Key DownKey Up

39.6


Due to the multi-fiber array of The MPO connector, it is

important to ensure that every fiber in the connector

can achieve a high attenuation and return loss performance. The

connector performance depends on multiple factors such as the

fiber-hole position, fiber-hole diameter tolerances, fiber protrusion

level, connector endface angle, alignment pin and hole tolerances

and connector cleanliness.

Before deploying MPO connectors, the end-to-end network design

must be decided. This includes the polarity of the MPO connector. As

with any patch panel involving MPO connectors, a fan-out from an

MPO to individual connectors, such as an LC connector is required.

In duplex networks such as a DWDM transport network, a pair of

fibers is required for the uplink and downlink. The confirmation of

these three parts of the network will help determine the two types

of MPO polarity for the MPO-MPO jumper and the MPO adapter key

orientation. The polarity types are as shown below:

Position 1 Position 1Fiber 1

Fiber 12Position 12 Position 12

Straight thorugh Fiber MPO Jumper

Key Down/Key Up adapter

Key Up/Key Up adapter

Flipped Fiber MPO Jumper

Fiber 1 Fiber 12

Fiber 12 Fiber 1

Position 1 Position 1







More features, same cost

More features,compared toconventional MPO

Flex Angle Boot

Bare Ribbon Fiber Short

Ribbon Cable

Bare Ribbon Fiber Mini


Bayonet Connector

EASYhANDlING

EASYASSEMBlY

Bayonet Connector


Multiple fiber termination in a single connector

Requires all fibers to be properly terminated for a high quality connector

Most compact fiber connector available in the market today with up to 72 fiber terminations in a single connector

All fiber terminations are affected if the connector needs to be de-mated to perform any operation on a single fiber in the connector

Simple push/pull operation The simple push/pull connector design without a latch is simplistic for a high fiber count termination

Lowest cost per fiber termination among all fiber connector types

Operator needs to be clear on the connector polarity

Growing in popularity for telecoms exchange and data center networks

Short length

of 37mm for 3mm roundMini Connector

Micro ConnectorUnique micro housing/ferrule design

Push-in and Removal tool

MPO Micro Connector ready Adapter

SENKO has a range of MPO connector solution for different deployment situation. a few of the solutions are:

• MPO MiniFeatures a shorter boot for space constrained situations and

enables polarity change in the field without any special tool and

changing the connector gender in the field.

• MPO MicroEnables an MPO connection without the connector housing. Able

to mate/de-mate the connector with a simple tool.

• MPO BayonetIntegrated turn lock connector boot to prevent accidental

connector de-mating.

• MPO LatchMPO connection with no housing that locks into a latch ready

adapter. The latch ready adapter is also compatible with

conventional MPO connectors.

• MPO-HdMPO connector with a pull-tab release trigger which allows the

connector to be easily disengaged without the need of a special

tool. This allows the connector to be densely packed.

• IP MPOMPO connector within an external housing for harsh environment

application.


MPO Mini MPO

IEC 61754-8CF08 Connector

IEC 61754-9dS Connector

IEC 61754-10Mini MPO Connector

The parent connector for the type CF08 connector family is a single-

way plug connector which is characterized by a conical ferrule butting

against a 4 mm diameter sphere or equivalent. It includes a push-pull

coupling mechanism and a ferrule spring loaded in the direction of

the optical axis. The plug has a single male key which may be used to

orient and limit the relative rotation between the connector and the

component to which it is mated.

The DS connector is also known as the F11 type connector based on

the Japanese standard JIS C 5980. The connector was only deployed in

very niche applications. The DS connector has a 2.5mm ferrule and has

an integrated sleeve design.

The Mini-MPO connector was developed based on the standard

MPO connector. The mechanism for the mating/demating and ferrule

polishing is exactly the same as the standard MPO connector. The

objective of the Mini-MPO connector is to increase the connection

density of up to four optical fibers. Although the standard MPO

connector can be manufactured for four fibers, the large MT ferrule

size requires high accuracy in fiber endface geometry to achieve

perfect physical contact.

The Mini-MPO uses a ferrule smaller than the MT, with the pitch

between the connector guide pins to be reduced from 4.6mm of the

MPO connector to 2.6mm. The structure of the Mini-MPO adapter

is also simplified by using a guide sleeve that is inserted into the

coupling sleeve instead of a reinforcing member. A table comparing

the MPO and Mini-MPO connector is as shown below.


Smaller connector footprint Only up to 4 fibers per connector

Higher insertion loss and return loss performance compared to MPO connector

Less fiber per connector area density compared to standard MPO connector

6,4mm

4,6mm

2,5m

m

4,4mm

2,6mm

2,5m

m

FER

RU

LEC

ON

NEC

TOR

Ad

AP

TER

9,6mm

5,0m

m

7,2mm

4,0m

m

6,4mm

9,8m

m

10mm

8,0m

m

39.7

39.8

39.9

Source: Tonichi Kyosan Cables


IEC 61754-12FS Connector

The FS connector is a duplex connector where the connector has

a pair of cylindrical spring loaded abutting ferrules of 2,5 mm

nominal ferrule diameter. The optical alignment mechanism is a rigid

bore or resilient sleeve contained within the adaptor. It includes a

hand-released latch coupling. The connector has multiple keyway

arrangements and the adaptor has multiple key configurations. The

keying scheme is exclusionary and is used to limit mating between

connector and adaptor to specific key combinations

IEC 61754-13FC Connector

The Fiber Connector or more commonly known as FC connector is

designed by NTT as an improvement of the ST connector which was

the first introduction of an optical connector with a 2.5mm ceramic

zirconia ferrule. This connector with a locking mechanism is designed

to be used in high vibration environments. The connector is commonly

used in telecommunication networks, data centers and measurement

equipment with singlemode fiber as well as polarization-maintaining

optical fiber.

Metallic ferrules have a different expansion coefficient compared

to optical fibers. This caused the epoxy adhesive to fail when the

metallic ferrule expands and contracts with the change in ambient

temperature. This is a process called “pistoning”. Ceramic ferrules have

a coefficient of expansion that is closer to optical fiber thus eliminating

the adhesive failure.

The FC connector has a screw on connector body which locks the

connector body, isolating the cable tension from the ferrule. The FC

connector and bulkhead adapter has an alignment key to enable

correct ferrule orientation especially for angle polished ferrules. The

bulkhead adapter of the FC connector has a metallic barrel which

becomes a risk for damaging the ferrule when it is improperly inserted.

The FC connector has a machined metallic body which is screwed

onto the bulkhead adapter for connector termination. This connector

was widely used in all optical network when it was first introduced due

to its high connector reliability and performance. The FC connector is

no longer widely deployed after the Introduction of the SC connector.

However, the FC connector is still commonly used in optical testing

equipment such as the Optical Time Domain Reflectometer (OTDR)

and Optical Continuous Wave Reflectometer (OCWR).

There are four standards for the FC connector. One standard for

the FC/PC connector, two standards for the FC/APC connector and

another standard which is applicable to either type of polishing. These

standards differ in the width of the alignment keys.

For the FC/APC connector types, one of them is referred to the “NTT”

or “type N” connector which has a key width of 2.09–2.14mm and an

adapter key width of 2.15–2.20mm. The other standard is known as the

“type R” which refers to its reduced key width. The type R connector

key width is 1.97–2.02mm and the adapter key width is 2.03–2.08mm.

The type R connector can be mated with a type N adapter, however

the connectors in the adapter may not be precisely aligned, thus

reducing the connector attenuation and return loss performance. The

type N connector cannot be terminated into a type R adapter as the

connector key is wider than the adapter key slot.


Has multiple keyway arrangements to enable specific connector and adapter mating

Large connector footprint


One of the first fiber optic connector with a zirconia ceramic ferrule

Machined metallic body is expensive to manufacture

Locking mechanism suitable for use in high vibration environment

Requires screwing and unscrewing which increases installation time and more operation space around the bulkhead adapter

Connector design reduces tension on optical fiber

Different connector standards may confuse user or result in sub-optimal performance

FC Square Adapter, Solid Body

FC Oval Adapter, HD Style FC Round Adapter, D Style

39.10

39.11


E 2000 Multimode

E-2000 APC

Crimpset

Connector Lever

E-2000 UPC

IEC 61754-15LSH Connector

IEC 61754-16PN Connector

The LSH connector, more popularly known as the E2000 connector,

is produced under license of Diamond, a Swiss company specialized

in customizing components and equipment. The E2000 name is

also trademarked by Diamond. The E2000 connector is also mainly

manufactured by Reichle & De-Massari (R&M) and Huber Suhner

under the license of Diamond.

The E2000 connector is a plastic push/pull connector with a 2.5mm

ferrule. The E2000 has a latch similar to an LC connector which holds

the connector in the bulkhead adapter to prevent accidental pull out.

In addition, the E2000 has an improvement by having a built-in dust

cap which automatically shuts when the connector is not terminated.

The auto shutter is designed with a lever at the top that is pushed to

open the shutter when it is inserted into the bulkhead connector. This

allows the connector ferrule endface to always be covered until it is

terminated to prevent contamination as well as provide protection

against accidental laser exposure.

The connector is used mainly in high safety and high powered

transmission such as in DWDM networks. In such high powered

networks, the E2000 adapter has an angled, anti-reflection surface

that induces light diffusion and low reflectance when unmated. The

adapter can also have an auto shutter which blocks laser light from

escaping an unterminated adapter.

In a harsher environment such as in an underground closure patch

panel, there is a possibility of water ingress in the closure when

it is improperly sealed. In such cases, optical connectors in the

compromised closure will experience reduced performance due

to contamination. The E2000 connectors and adapters can have an

additional O-ring seal which makes the connector itself have an IP65

rating. This prevents water from entering the adapter barrel where the

ferrules mate.

The PN Connector is also widely known as Plastic Fiber (PF) connector.

This connector is used mostly for Plastic Optical Fiber (POF) multimode

application. The connector has a duplex design with both the lever

locking and friction locking mechanism.


Connector with integrated auto-shutter and adapter can also be shuttered

High cost for a connector performance similar to an SC connector

Have the option to include an O-ring seal for an IP65 rated connector


Uses both lever locking and friction locking mechanism for high connection reliability

High loss connector

39.12

39.13

Source: Honda Tsushin Kogyo


The Mechanical Transfer Registered Jack, or better known as the MT-

RJ, connector was introduced by AMP in the late 90’s as a low cost

connector that looked like the copper RJ45 style connector. The

connector is a Small Form Factor (SFF) duplex connector, with two

fibers in a single connector, designed to terminate into an Ethernet

port of a computer modem or router. A single mini MT plastic ferrule

houses two fibers spaced 750µm apart instead of the more prevalent

ceramic zirconia ferrule. The connector is based on the multi-fiber MT

ferrule designed by NTT.

The MT-RJ connector is usually used for multimode optical fiber but

is also applicable in single mode networks. The connector is a Small

Form Factor (SFF) duplex connector. The MT-RJ connector is used

more in multimode networks due to the lower cost to manufacture

the glass-filled thermoplastic ferrule by standard injection molding

compared to a single mode ferrule that requires a more precise

glass-filled thermoset ferrule that must be transfer molded, which is

a slower process.

The MT-RJ is separated into a male and female connector. The male

connector has two guide pins that slots into two holes of the female

connector within the MT-RJ adapter to align the ferrules for connector

termination. As a general practice, the male connector is usually

terminated in the patching back panel, wall outlets or transceivers

while the female connector is used at the ends of jumper cords. This

practice is to set the male connectors in a static position to protect

the guide pins from accidental damage. A male to female patch cord

is used in the event where a mid-span connection is required. Some

unique MT-RJ connectors allow for the guide pins to be removed or

inserted to interchange the connector gender.

The connector has a latch that is designed similar to the copper

RJ45 connector. A single latch positioned at the top of the connector

locks the connectors within the bulkhead adapter. Depending on the

connector material, latch angle and arm deflection, the latch strength

differs. This causes a varying connector coupling performance

from different manufacturers which complicates the connector

performance consistency.

Due to the unique ferrule, the initial cable designed to be terminated

with the MT-RJ connector was a two fiber ribbon which separates the

fiber with a 750µm pitch which is similar with the fiber pitch in the

ferrule. Although cord construction eases the fiber insertion process

into the MT ferrule, it complicates the process when a hybrid patch

cord is manufactured. The second cord design iteration include a

two 250µm fiber within a 900µm buffer tube which was suitable for

a hybrid jumper manufacturing but complicated the fiber insertion

process into the MT ferrule. The third iteration was two 900µm buffer

tube within a jumper but this design still presents a complication in

the fiber insertion process. To overcome the fiber pitch issue, some

connectors are designed with a fiber transition boot that guides the

fiber into a 750µm pitch.

A field installable MT-RJ connector but the assembly was complicated

and requires specialized tools such as a crimping tool, VFL with dual

light source and an MT-RJ to two simplex connectors are required

to terminate the fibers. The fiber preparation requires both fibers

to be stripped and cleaved with the same length. During the fiber

insertion process, both fibers need to be inserted at the same time

and the insertion length must be similar to prevent one fiber from

over bending within the connector boot. In addition, the operator

must be very clear on the polarity of the fibers. Due to the high skill

required and the high potential for failure, the field installable MT-RJ

was not popular.

IEC 61754-18MT-RJ Connector


Inherently a duplex connector that is suitable for a multimode network.

Very poor single mode performance and higher connector cost

Small form factor connector reduces patch panel real estate requirement

Male/female connector incompatibility

Difficult to test as most test equipment do not have a direct connector termination to the MT-RJ connector. Requires an intermediate patch cord to convert to an SC or FC type connector.

750µm fiber pitch is a mismatch with standard fiber buffer coating.

Complicated process for proper termination in a FIC assembly.

MT-RJ Female Connector Standard

MT-RJ Male Connector Standard

39.14


IEC 61754-19Sg ConnectorMT-RJ Connector

The SG connector, or better known as the Volition VF-45 connector,

was developed by 3M as a low cost solution for fiber interconnectivity

for fiber-to-the-desktop application. The connector removes the need

for ferrules but instead uses the v-groove fiber alignment technology.

The connector is designed to have the same appearance and

operation of a standard RJ45 connector.

The VF-45 connector is factory terminated with a fiber holder which

secures two or more fibers in place, a shroud and boot which protect

the fibers and secure the cable to the connector and an integral door

which acts as a dust cover. The VF-45 socket is field assembled without

the need of precision alignment tools. The v-groove aligns the fibers

within the socket and a mechanical grip holds the fibers securely in

place. The field assembled sockets are installed into wall outlets and

patch panels similar to RJ45 keystones.


Low cost without the use of ferrules Proprietary connector design by 3M

Uses the familiar RJ-45 style latching Only sockets can be field assembled

Easy field assembly for sockets

Suitable for Single Mode and Multi Mode fiber

39.15

Source: 3M

bernlee

Rectangle


LED Traceable Lighthow to:

The LED starts Flashingemitting a red light21 Push the button to

activate the LEDThe LED light is Visible on theother end of the patch cord3

IEC 61754-20LC Connector

The LC connector is designed by Lucent Technologies as the next

generation Small Form Factor (SFF) connector with a 1.25mm ferrule.

This is effectively half the size of an SC connector. The connector uses

a retaining tab mechanism to lock the connector when plugged into

a bulkhead adapter for a single fiber termination. LC connectors also

come in a duplex form for two simplex fiber terminations or quad

form for four simplex terminations.

LC connectors have been gaining popularity due to its small footprint

which saves precious network space and is currently the most common

SFF connector. The LC connector can be used with singlemode and

multimode fiber. The main area of application are telco networks such

as FTTH, LAN, data processing, device termination, CATV, cell towers &

antennas.

Further development of the LC connector latching mechanism and

boot enables the connector to be further packed into a smaller

space. The SENKO LC-HD connector has a pull tab which activates the

latching mechanism which releases the connector from the bulkhead

adapter. This removes the need for “finger space” between connectors

to fit an operator’s fingers to push onto the latch.

With an increased connector density, connector identification

becomes complicated. Such problems can be solved with new

connector identification technology such as RFID tagging and visual

LED lighting system. One such example is the SENKO EZ-Trace LC

which indicates the connector at the far end when a button on the

connector is pushed.

2.0mm MINI Boot

3.0mm MINI Boot

900µm MINI Boot

39.16


IEC 61754-21SMI Connector

IEC 61754-22F-SMA Connector

Molex developed the Small Multimedia Interface (SMI) for Plastic

Optical Fiber (POF) connector and transceiver system. The SMI

connector was designed to be a low-cost solution for home and

industrial transmission system. The connector is mostly used in home

networking, High Definition video display, home audio and theater

system as well as industrial network.

The SMI is a duplex connector system that can operate at S200

(250Mbps) speeds for up to 50 meters and S400 (500Mbps) in the

future. The SMI has a push-pull positive latching with a safe-release

mechanism.

The connector has a no-epoxy, no polish solution enables a quick

and simple field-termination process. The SMI solution also includes

a transceiver with a digital integrated fiber optic transmit and receive

modules.

The F-SMA connector is one of the first generations of fiber optic

connectors. The connector uses a metallic ferrule where the fiber end

is free from epoxy glue. This allows for better thermal dissipation in the

fiber region of maximum power density. The body of the connector

and adapter are metallic and is a screwed on design.

The connector is designed for multimode fiber use and is mainly used

in high powered application such as industrial and medical systems

where short and medium range performance is required.


Low cost connector solution Limited bandwidth and distance

Easy field termination solution


Connector suitable for high powered application

High costconnector

39.17

39.18

Source: Design World

Source: Diamond


IEC 61754-23LX.5 Connector

IEC 61754-24SC-RJ Connector

The LX.5 connector was introduced by AMP in the late 90’s as one

of the many Small Form Factor (SFF) connectors that gained in

popularity. The LX.5 was marketed as part of ADC’s premises cabling

system called Enterprise. The LX.5 connector adoption is largely

confined within the European markets.

Similar to most SFF connectors at that time, the LX.5 connector uses

a 1.25mm ferrule in a connector. The connector and the shutter has

a built-in shutter designed for eye safety. The spring loaded shutter

automatically rises as the connector fits into the adapter and returns

to fit over the ferrule when the connector is removed. The LX.5 is

available in a simplex and duplex form as single mode and multimode.

The LX.5 connector also has an integrated latching mechanism

that locks the connector into the adapter to prevent unintentional

disconnection.

The Subscriber Connector Registered Jack (SC-RJ) is a push/pull

Small Form Factor (SFF) developed by Reichle & De-Massari (R&M)

primarily for Ethernet and Fast Ethernet network connections of up to

100Mbps. The SC-RJ is the first connector to be specified for used with

all fiber types which are glass optical fiber, polymer optical fiber and

plastic cladded fiber. The connector can be used for both multimode

and single mode fiber.

On first look, the SC-RJ looks very similar to an SC duplex connector

but there is a difference. Although the SC-RJ is based on the better

known SC connector technology, the size of the SC-RJ is suitable to be

fitted within a standard RJ45 connector. Similar with the SC connector,

the SC-RJ connector uses the 2.5mm ferrule. The SC duplex connector

has two keys on top of each connector. However the SC-RJ connector

has three keys, one each facing the left, top and right side of the

connector.

The connector is specified for use with The SC-RJ is mainly used

in office networks, campuses and industrial application. R&M has

also developed an IP67 SC-RJ connector for higher environmental

protection especially in industrial conditions. In addition, a field

installable solution is also available, however the fiber preparation is

very tedious, requiring the cord and fiber length to be accurate as well

as the fiber polarity.


Small Form Factor connector that can be duplex

Less robust than the standard LC connector

Shuttered connector Not widely adopted in the market

Latching mechanism to prevent unintentional disconnection


Able to be used for all types of fibers Not widely adopted

Available in IP67 option Difficult to prepare the field installable connector

39.19

39.20

Source: Huber + Suhner

Source: RDM


IEC 61754-25RAO Connector

IEC 61754-26SF Connector

The RAO connector is a multi-fiber connector which uses the MT

ferrule. This connector is designed with a built-in right-angled bend.

Due to the right-angled bend design, the connector requires the use

of fiber with low bending loss at 30mm bending radius so that the

radius of curvature at the 90 degree bend is maintained with a low

permissible loss.

The optical connection is the physical contact of optical fibres with

the rectangular MT ferrules with nominal dimensions of 6.4mm x

2.5mm which uses two 0.7mm diameter alignment pins.

The RAO connector enables the termination of up to four MT ferrules

in a single termination. Even when less connections is required, the

connector needs to termination of four MT ferrules to maintain the

connector balance. This connector is mainly used in equipment

termination board and for fiber testing equipment.

The SF connector is a low cost, high density connector developed by

NTT. The connector is designed to enable a direct multi fiber contact

by using micro holes without the need for ferrules. This allows the

SF connector to have a manufacturing cost of nearly a quarter of

standard multi-fiber connectors such as the MPO connector.

The connector is a plug which holds multiple fibers that are laid out

in a plane. The ends of the cleaved fibers protrude out of the plug. The

connector is terminated into a receptacle block that has micro holes

to align the fibers. One side of the fibers in the plug has a very small

micro bend when fully terminated. This is to ensure that the end faces

of the terminated fiber is pushing onto the fibers on the other side.

When two SF connectors are terminated into a receptacle block, a clip

similar to the MT connector is used to hold the connectors together.

The SF connector is mostly used for fiber termination in equipment

which has space constraints.


Multi-fiber terminationin a single connector

Requires four MT ferruleseven if less fiber termination is needed


High densityand low cost connector

Weak connector that is only suitable to be used in a protected environment

Multi-fiber terminationin a single connector

39.21

39.22

Source: IEC

Source: NTT


IEC 61754-27M12 Connector

IEC 61754-28LF3 CONNECTOR

The M12 connector is a robust and watertight connector that is

suitable for glass optical fiber, plastic optical fiber and photonic-

crystal fiber. The connector is designed to protect the dual 2.5mm

ferrules endfaces during termination. Depending on the connector

design, the M12 connector can have an IP65 or IP67 protection.

The dual ferrules are at a level below the connector housing, thus they

are not exposed. The connector and adapter has notches which aligns

the connector before the ferrules are slid into the adapter barrel.

This ensures that the ferrules are not accidentally damaged during

connector termination.

The M12 connector is usually used in industrial application where a

more rugged connector assembly is required with a high IP rating,

tear-resistance, strain relief and other environmental protection such

as UV resistance.

The LF3 or better known as the F-3000 connector was developed

by Diamond as the next evolution from their E-2000 connector. The

F-3000 connector was standardized as the LF3 connector in the IEC-

61754-28 standard.The F-3000 connector includes all the technical,

mechanical and optical features of the E-2000 connector in a Small

Form Factor (SFF) footprint. The connector is available as a simplex,

duplex as well as for backplane application. The connector is fully

compatible with the more widely deployed LC connector.

The F-3000 connector uses Diamond’s patented two-part ferrule

and Active Core Alignment (ACA) technology. The assembly involves

two crimping tools that determines the position of the ferrule center

location and pushes the optical fiber core towards this center location.

This ensures the core concentricity error to be less than 0.2µm.


Highly robust connectorfor industrial application

High cost connectordue to robust design.


Small Form Factor connectorthat can be duplex

High cost connector

Shuttered connector and adapter Not widely adopted in the market

Latching mechanism to prevent unintentional disconnection

39.23

39.24

Source: Phoenix Contact

Source: Diamond


IEC 61754-29BLINK Connector

IEC 61754-30CLIK! Connector

The BLINK connector was introduced by Huber+Suhner as a customer

premises connection from the Internal Termination Point (ITP) to the

Customer Premises Equipment (CPE) such as the Optical Network

Terminal (ONT). Taking into consideration of general end customers

who do not have the skill nor experience in handling optical fiber

termination, the BLINK connector is designed to be a simple to use

jumper similar to an Ethernet cable.

The BLINK connector follows the standard Small Form Factor (SFF)

connector size and uses a 1.25mm ceramic zirconia ferrule. The BLINK

connector and adapter is designed to have an automatic metallic

shutter to protect the endface of the connector and adapter from dust

and mechanical damage. In addition, it also acts as a safety feature to

prevent exposure to laser light.

One additional feature of the BLINK connector is the auto disengage

from the adapter when the cable is accidentally pulled. Although

the connector can withstand 100N tensile load, this feature prevents

connector damage from a sudden high tensile stress. This design is

similar to standard home cabling for power, HDMI or USB connection.

The BLINK adapter is designed to enable connection to the BLINK

connector to standard LC or SC connector. The design enables the

outward facing side of the adapter to be terminated with the BLINK

connector but the inward side to be suited for conventional LC and SC

connectors that will be installed by trained fiber technicians.

A new keystone adapter, also known as modular jacks, is designed to

enable the fiber termination from a pre-terminated CLIK! Connector

at the back and the BLINK connector from the front. This enables fiber

termination to be available in existing keystone outlets rather than

needing a new fiber outlet.

The CLIK! System was introduced by Huber+Suhner in 2011 for Master

Antenna Television (MATV) and Direct-To-Home (DTH) applications.

The system enables a quick and easy method to divide signal from a

fiber optic Low Noise Block (LNB), designed for commercially available

satellite systems, with matching splitters to deliver signal to multiple

customer premise equipment. The CLIK! System aims to replace

conventional coaxial cable network for satellite signal distribution.

The CLIK! System is currently deployed in Switzerland, Italy, Austria

and Germany.

The CLIK! System aims to use existing ducting within a customer

premise and using existing cabling within the duct as a pull cable

to haul in new fiber optic cable. The connector is designed to have a

small 5mm diameter suitable for hauling in ducting. In addition, the

connector is designed with a pulling eye to enable up to 100N pulling

tension. The connector can then be terminated into a splitter unit for

distribution throughout the customer premise.

The CLIK! System includes a two-way and a four-way splitter, each

with different distribution requirements that are used based on cable

lengths and connectors. Three-way and five-way splitters will also

soon be available.


Shuttered connector and adapter Proprietary connector and system

Auto disengage featureHigher cost compared toconventional patch cords


Small connector enables pre-terminated cable hauling through existing conduit

Proprietary connector and system

Connector has an integrated pulling eye

39.25

39.26




IEC 61754-31N-FO CONNECTOR

IEC 61754-32diaLINK CONNECTOR

The N-FO connector which is also known as the ODC (OutDoor

Connector) was introduced by Huber+Suhner in 2015 as a robust

connector for Remote Radio Head (RRH) terminations. Huber+Suhner

identified that damage to optical fiber interfaces is one of the main

causes of defects during RRH installations, thus the ODC is designed

as a robust outdoor connector to handle harsh environments and

rough handling.

The ODC family comprises of a two-way and four-way push-pull

circular plug connector and socket set. Each fiber is housed within

a spring loaded 1.25mm ceramic non-angled ferule. The plug

connector has a key which fits into the socket keyway to align the

connector ferrules before termination. The socket has a spring loaded

threaded coupling nut which can be tightened after the connector is

terminated.

The ODC provides harsh outdoor environment protection where RRH

are installed such as in coastal areas, urban buildings or rural tower

sites. The ODC can withstand temperature extremes, vibration, salt

mist, corrosive gases and high humidity.

The DiaLink connector family was introduced by Diamond in 2016

as a flexible pre-terminated fiber optic cabling solution suitable for

installation in confined spaces with its slim 6mm connector design.

The DiaLink connector is designed for a wide range of application

including FTTH deployment, fiber optic LAN and medical applications.

DiaLink uses a 1.25mm ferule in a simplex connector with a push-pull

coupling mechanism. DiaLink has a male and a female connector side.

To provide adequate ferule contact, the male side of the connector

has a spring-loaded ferule while the female side has a fixed ferule. The

connector does not require an adapter for termination. Instead, the

fixed-ferule side of the connector has an integrated adapter sleeve to

provide connector alignment.

The DiaLink-Saver connector is designed with a breakaway coupling

device. The connector separates the fiber optic termination when

subjected to a sudden pull force where the separated connectors can

be easily re-terminated without the need of special tools. The end

faces of disconnected DiaLink-Saver connectors are protected from

the environment, thus they can be re-terminated without the need

for end face cleaning. There are also adapters available to terminate a

DiaLink connector to an E2000 connector.


Robust connector suitable for harsh environment


Multi fiber connector


Small footprint enables easy installation in confined spaces


DiaLink-Saver have integrated connector end face protection mechanism

Only available in a simplex connector design

39.27

39.28


Source: Diamond


IEC 61754-34URM CONNECTOR

The URM (yoU aRe Modular) fiber optic connector is introduced by

EUROMICRON Werkzeuge GmbH, a company that specialized in

high-tech solutions for digital buildings, smart industry and critical

infrastructure. The URM connector was certified in the IEC 61754-34

standard in October 2016.

The URM is a modular multi-fiber connector system with a small form

factor design for high density data center network application as a

higher performance alternative to MPO connectors. The connector is

available as a two fiber and eight fiber connector with both PC and

APC polished ferule.

Unlike MPO connectors where multiple fibers are terminated in a

single connector, each fiber in the URM connector is guided within

their individual 1.25mm spring loaded ceramic ferule. This enables

each fiber end face to be polished separately. The connector

termination alignment is guided by a resilient sleeve. The modular

design of the connector also enables the connector polarities to be

changed.

The URM connector is specified to achieve low insertion loss of less

than 0.2dB. This is critical in low loss budget links such as 100GbE and

400GbE links.


Low loss connector alternative to MPO connector for data center application


High density and modular design

39.29

Source: Euromicron


The development of this white paper benefited significantly from the input and support provided by our partner, JGR Optics Inc. Their feedback

and guidance has provided invaluable insights, and the background information they provided has been vital to the development of this white

paper. We would like to give special thanks to each member of their team for sharing their time and expertise with us.

Biography

Bernard H. L. Lee is currently the Regional Technology Director at SENKO Advanced Components. He started his career in optical

communications in 2000 as a Senior Research Officer for DAVID, a European Union IST project. In 2003, he joined the R&D division at

Telekom Malaysia, where he held various technical and management positions, including Head of Photonic Network Research and

Head of Innovation and Communications, before joining the parent company in 2010 as Assistant General Manager of the Group

Business Strategy Division, where he oversees the company’s business direction. Bernard is also a member of the International

Electrotechnical Commission (IEC) and the Institute of Engineering and Technology (IET), and has served on the Board of Directors

of the Fiber-to-the-Home Council APAC.

Tomoyuki (Tom) Mamiya currently manages Engineering and QA Group of SENKO Japan. He joined SENKO Japan in July 1999,

and then joined SENKO Advanced Components in the United States to manage all global engineering efforts as a Engineering

Manager in February 2000. He worked in various engineering and product development positions before being promoted to

Global Vice President of Engineering in 2006. Prior to joining SENKO, he had worked for fiber optic component and equipment

manufacturing company in Japan for more than 5 years as R&D engineer. He hold over 10 patents in fiber optic component field

in world-widely, in the US, Euro, Japan, and Taiwan.

Acknowledgement

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