FOA Basic Skills

Lesson 5: Fiber Optic Termination (Connectors)

Objectives: From this lesson you should learn:
How to identify common fiber optic connectors
How to install connectors using several methods
Adhesive/polish (epoxy, anaerobic and Hot Melt)
Singlemode fiber polishing
Prepolished/splice w/mechanical splice (requires special tools)
Fusion splice-on connector (SOC) (requires fusion splicer and accessories)

Tools And Components Needed
Fiber stripping tools, crimper, Kevlar scissors, etc. or a termination toolkit
Polishing plate, pad, puck and film (12, 3 and 0.3-1micron)
Fiber to splice, preferably a simplex cable or half a zipcord
Download the list of tools and components  needed or refer to the CFOT Certification Lab Manual


Termination refers to the process of installing connectors on the ends of a fiber or fibers in a fiber optic cable. Over the history of fiber optics, there have been over 100 different types of fiber optic connectors designed using at least a dozen ways of attaching the connector to the fiber. Today, factory made connectors use heat-cured epoxy connectors that are generally polished on a machine. Field termination may use adhesive/polish techniques with either heat-cured epoxy, room temperature cured epoxy, anaerobic adhesives or HotMelt ( a 3M product name) or prepolished/splice connectors which have a short stub of fiber inside the connector that are attached with mechanical or fusion splices.

polish connector
Polishing an adhesive/polish connector.

The purpose of this lesson is to show you how to install connectors using the most popular methods. It is recommended that everyone do at least one of the adhesive/polish connectors and one prepolished/splice connector type.

We have provided step-by-step instructions you can follow. If possible, get instructions from the manufacturer of the connectors or the tool kit
you are using and follow them as each manufacturer's connector may have some subtle differences.
Work in a space where you will not be disturbed and avoid distractions. It is important you concentrate on the exercises and follow each step carefully.
Allow plenty of time to complete the exercises without interruption, especially this one on termination. During the termination exercise, you will use adhesives which must be used quickly.

Lennie works safe Please Note: This is not the usual online course - it is intended to guide you as you learn new skills - the "hands-on" skills needed to install optical fiber cable plants. It involves using tools and components in a realistic manner. Some of the processes here can be hazardous, like working with sharp scraps of optical fiber and chemicals.

In Lesson 1 you should have familiarized yourself with the safety procedures - follow them all the time. Do not work with fiber without eye protection and a proper work area that is easy to clean up.  Always wear safety glasses when doing any of these exercises and dispose of all scraps properly.

As part of Lesson 1, you should have watched the FOA YouTube Video: FOA Lecture 2: Safety When Working With Fiber Optics      

Download a FOA safety poster for your work area.

Background Review
This "skills" course assumes you have knowledge of fiber optic termination. If you are new to fiber optics, you review the FOA Guide section on Termination and Splicing or should  complete the
Fiber U Basic Fiber Optics: Termination and Splicing course before attempting the hands-on exercises here.

Hands-On Lab Instructions

Download and read the Workbook termination and the VHO tutorials on termination for the types of terminations you will be doing linked below.

Watch the videos and/or read the VHO Tutorials on the termination types you have available for practice or are interested in learning. The
VHO  "Virtual Hands On" Tutorials take a "step-by-step" approach to the hands-on processes covered in this self-study program and the videos will show the processes in motion. They are both a good way to teach yourself the processes here - watch the video for the overview then follow the steps in the VHO web pages.

*Note: Everyone should study the VHO for Epoxy/Polish connectors since this is the method used for patchcords and cables terminated in factories, representing the lmost common termination type. The other types can be chosen depending on personal interest.

Complete the exercises with the equipment you have available following the steps in the appropriate VHO Tutorial.

Workbook Section (PDF)
VHO Tutorial (PDF)
Video (YouTube)
Lesson 5: Fiber Optic Termination Termination Epoxy/Polish
Hot Melt  
Pre-Polished Splice& SOC  Singlemode

EasySplicer SOC
Cable Prep
Stripping Fiber
Connector Attachment
Distribution cable (900 micron buffer)
Connector Polishing Technique

Corning Unicam
Panduit Opticam

Hands-On Assignments

After reading the workbook section and VHO tutorial and watching the videos, complete these exercises using all the cable types available to you.

As you finish each section, fill in the worksheet in the back of the Workbook on Termination. Your completed worksheets are the records of your having successfully completed the exercises.

Each of these exercises involves terminating a tight buffer fiber or simplex fiber optic cable with a common type of connector.

You should complete the exercises for the all the components and tools available to you, although it is recommended that you learn how all these methods are done to understand the complete process of fiber optic termination.

Before starting the hands-on exercises, we recommend you read these pages in addition to the Workbook section and the VHO tutorial:

Adhesive/polish connectors

Hints For Adhesive/Polish Connector Terminations

Termination Workspace
Arrange all your tools, components and other items on your work table. Using a black mat (black Naugahyde works well) makes it easier to see the fiber when working.

Epoxy and anaerobic adhesive techniques use the same connector type, the basic ceramic ferrule connector. The 3M HotMelt connector is only made by 3M and will require the 3M connectors and oven. Prepolished/splice connectors are available from many manufacturers but will generally require the termination kit from that particular manufacturer.

We recommend starting with either SC or ST connectors with a 2.5mm ferrule as they are somewhat easier to terminate than the smaller 1.25mm ferrule of the LC. After mastering the techniques, try the LC connectors with smaller ferrules.

connector parts
Parts of an ST connector

Hint: Since it is preferred to be able to test each connector as it is made, we recommend starting with a long patchcord, say 5 meters long, then cut it in half and attach your connector to the cut end. That allows testing your connector as soon as it is made using the single-ended (patchcord) test. Record all test data on your connectors.

Adhesive/Polish Connectors
Adhesive/polish connectors all have a similar process (from left): strip the fiber to the proper length, apply adhesive and insert the connector,
after the adhesive sets, cleave the fiber, air-polish to remove most of the fiber stub, final polish on a flat plate with a soft polishing pad.

Fiber Optic Connector Termination

Fill in the worksheets at the end of the Workbook section on Termination as you complete the tasks.

1. Epoxy/polish Connectors

Read: Adhesive/polish connectors
VHO: Epoxy/Polish

Follow the directions to terminate a fiber or simplex cable. The 8-part videos above give detailed instructions.
The VHO:  Epoxy/Polish web pages show step-by-step instructions that are easy to follow.

Epoxy-polish  connector
Epoxy must be injected into the connector with a syringe.

Inject adhesive until it forms a small bead on the connector ferrule. When this bead hardens, it supports and protects the fiber during polishing to allow a better end finish. This hardened bead of epoxy means the yield of epoxy/polish connectors is nearly 100%. Thus epoxy/polish connectors have the highest yield, best reliability and lowest loss of any termination type.

Epoxy bead
Inject epoxy until you see a small bead of the adhesive on the end of the ferrule.

Many novices think epoxy connectors take too much time - it does take 5-10 minutes to cure epoxy in an oven. But if you are terminating more than one connector, the first connector goes into the oven and will be ready by the time the second or third connector goes in the oven, so the curing time is irrelevant.

Epoxy usually only has a 30 minute life once mixed. If you are working with others, you can share the epoxy to be more efficient.

If you have a curing oven, the epoxy will cure in 5-10 minutes. Room-temperature curing epoxy will need to be left overnight.

2. Anaerobic /polish Connectors

Read: Adhesive/polish connectors

Several methods are used for applying an adhesive and some use an “accelerator” or chemical thatmakes the adhesive set instantaneously. These methods are:
  • Inject adhesive into the connector and dip the prepared fiber end into the acceleratorbefore inserting it in the connector. One must work quickly as the adhesive sets in 30 seconds or so, so if trouble getting the fiber intothe connector is encountered, the adhesive may set before the fiber is fully inserted.
  • Inject adhesive into the connector and then insert the prepared fiber end into the connector. Spray or drop theaccelerator on the protruding fiber and move the fiber back and forth to spread the accelerator inside the connector ferrule. It should set in ~30 seconds.
  • Wipe the fiber with the adhesive and insert it in the connector. With noaccelerator, the adhesive will set in 4-5 minutes and be much stronger. If instant adhesion is required, spray or wipe accelerator on theprotruding fiber as above.

The original method developed decades ago was to inject the adhesive in the connector then dip the prepared fiber in the accelerator and insert it. The problem with this method was the adhesive would set so fast that often one could not get the fiber fully inserted in the connector before the adhesive hardened, requiring the connector to be discarded. Try this method also to see if it works for you.

When cleaning fibers for anaerobic connectors (or any connector for that matter), NEVER use regular medical alcohol or alcohol pads. The 30% water content makes the adhesive take much longer to cure (if it ever cures) and makes the bond to the connector ferrule less strong.


3. 3M HotMelt Connectors: 

Read: Adhesive/polish connectors
VHO: Hot Melt 

Follow the directions to terminate a fiber or simplex cable. The VHO gives detailed instructions.
VHO:  Hot Melt 

HotMelt connectors use an adhesive that is applied to the connector at the factory and is then heated up to liquify it to allow insertion of the stripped and cleaned fiber. The connector is then set aside to cool and set for several minutes before the fiber can be polished.

For this exercise, you will need a special 3M Hotmelt oven. HotMelt ovens use a much higher temperature than epoxy overs, so they are not used for any other purpose - the high temperature will ruin epoxy.

3M HotMelt connectors
Inserting a HotMelt connector in a 3M oven

One advantage of the HotMelt connector is you may be able to reuse them. If you break the fiber or have problems in the cleaving or polishing process, you can heat the connector up and remove the fiber and try again. Or you can strip the fiber ~3mm (1/8") longer and after inserting it fully, pull it back 3mm and let it set. If you have problems with
cleaving or polishing, reheat the connector, push the fiber fully in, let it cool and try again.

4. Prepolished/Splice Connectors

Corning Unicam

Read: Prepolished/splice connectors 
VHO: Pre-Polished Splice& SOC
Hands-on lab with step-by-step directions

Follow the directions to terminate a fiber or simplex cable. The VHO gives detailed instructions. VHO: PPS Termination 

Prepolished/splice connectors are connectors with a short fiber stub already installed in the connector and polished, allowing the connector to be installed on a fiber using a splice. The splice has traditionally been a mechanical splice but fusion splices are now available for use with some connectors, sometimes requiring special splicing machines, sometimes regular fiber splicers.

Each manufacturer's prepolished/splice connector is slightly different. It is important to follow their instructions exactly to get good results.

The most important issue with any prepolished/splice connector is to ensure the fiber is cleaved properly. Many kits for these connectors provides only a simple, cheap cleaver that looks like a stapler. If used properly, these cleavers can provide adequate cleaves, but they require practice and a technique that not every tech can master. More expensive cleavers such as those used for fusion splicing are recommended to prevent problems. 
Remember that a poor cleave will not only cause high loss, it usually causes the need to cut off and discard an expensive connector.

5. Fusion Splice-On Connectors (SOC)

Fusion Spice-On Connectors

Read: Prepolished/splice connectors 
VHO: Pre-Polished Splice& SOC, Detailed sequential instructions on installing a SOC using the EasySplicer (shown above.)

The SOC is a prepolished connector made in a factory with a short length of cleaved fiber that is fusion spliced onto the fiber being terminated. The SOC process is straightforward, much like fusion splicing. Strip the fiber, cleave it with a fusion splice cleaver, place the connector in the fixture in the splicer, fuse the fibers, shrink a protector over the splice and place the boot on the connector.

Each manufacturer's SOC is slightly different. It is important to follow their instructions exactly to get good results. 

6. Singlemode Polishing: Follow the directions to terminate a fiber or simplex cable. The VHO gives detailed instructions.

Read: Singlemode fiber termination

Not many techs attempt field installation of singlemode connectors using adhesive/polish techniques. It is very hard to get low loss and especially reflectance with hand-polished SM connectors so most are factory terminated on a pigtail which is fusion spliced onto the fiber in the field. Furthermore, most SM connectors are tested with an interferometer to verify the quality of the end finish. However we offer instructions to those who want to learn how to polish SM connectors.

interference test
Interferometer test of a SM connector

If you do not have access to an interferometer but want to know how good your connectors are, use a reflectance test to check them. Read: Reflectance Testing 

Have you completed the Workbook worksheets that are the records of your having successfully completed the exercises?

Test Your Comprehension - Online Quiz On Termination  

Next:  Lesson 6: Fiber Optic Testing          


Get a "Certificate of Completion" When You Complete The Course
After you complete 
complete all six lessons of the Fiber U Basic Skills Lab Fiber Optics online self-study course, you can now take an online exam and, when you pass the exam, get a "Certificate of Completion" for this course. You should complete all lessons including taking the quiz ("Test Your Comprehension") at the end of every lesson. When you think you are prepared, you can take an online exam for a nominal fee ($20) which will give you a "Certificate of Completion" for this course.

Take the Test to Get Your Certificate of Completion For This Course  

Return to Lesson Plan


Table of Contents: The FOA Reference Guide To Fiber Optics

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