FOA Basic Skills

Lesson 4: Fiber Optic Splicing

Objectives: From this lesson you should learn:
How to concatenate* fibers by splicing
Mechanical splicing
Fusion splicing
Mass (ribbon) splicing

*Concatenate is a term used to describe the process of joining two fibers together.

Tools And Components Needed
Fiber stripping tools
Fiber to splice (if at least one is a long pigtail, it will make testing splices easier)
Mechanical splices
Fusion splicer


Splicing is used to concatenate fibers when joining two cables or terminating cables with factory made pigtails (a cable with a connector on one end.) Mechanical splicing uses a small alignment device and index matching gel. Fusion splicing welds fibers together in an electrical arc. Mass fusion splicing or ribbon splicing uses fusion splicing techniques on a dozen fibers or more at one time.

field splicing
Splice tech working onsite in a trailer.

Placing spliced fibers in a splice closure.

The secret to a good splice is good cleaves. Unless the cleave is good, the joint between the two fibers cannot be made properly. Fusion splicers come with high-quality cleavers but some mechanical splice kits use inexpensive cleavers that require practice to make good cleaves. (3M has an interesting low-cost cleaver that is included in their kits that uses a diamond wire to cleave the fibers. You use it about 100 times then discard it. Video on the 3M disposable cleaver.) Investing in a good cleaver will make a big difference in the quality of the splices you make.

Both fusion splicing types seal the fused fibers in a sealed protector. Spliced fibers are placed in a splice tray which is in turn placed in a splice closure. Besides practicing cleaving, you should practice placing buffer tubes and fibers in trays and closures.

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.


Please Note: This is not the usual online course - it is intended to guide you as you learn new skills - the 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. The first lesson is about safety - we recommend reading it carefully and posting the safety rules for everyone to see. Always wear safety glasses when doing any of these exercises and dispose of all scraps properly.

These guidelines are strictly the opinion of the FOA provided for educational purposes and the reader is expected to use them as a basis for learning. The FOA assumes no liability for the use of any of this material.

Familiarize yourself with the safety procedures and follow them all the time.

A pair of safety glasses must always be worn.

Be careful when working with sharp tools.

We recommend working on a black table mat to make it easier to see the fiber (and any scraps). It is best to work on tile or concrete floors, not carpet. If you drop fiber scraps into carpet they can be very hard to find or pick up with a vacuum cleaner.
Clean up after your exercises carefully. Some of the scrap you generate can be harmful, such as fiber ends, so we recommend you not work anywhere near food preparation or children’s play areas! Place clean paper over your work area to keep from harming the worktable surface.
Download a FOA safety poster for your work area.

Background Review
This "skills" course assumes you have knowledge of fiber optic termination and splicing. If you are new to fiber optics, you should first complete the "Fiber U Basic Fiber Optics" course before attempting the hands-on exercises here.

Fiber U Basic Fiber Optics: Termination and Splicing 

Hands-On Lab Instructions

Student Assignment:
Watch the videos and/or read the references and complete the exercises. Videos show processes in real time. VHO (virtual hands-on) web pages are step-by-step instructions on how to complete the hands-on projects. Both should be used to learn and do each of the processes.

YouTube Videos
FOA Online Reference
FOA Textbook

FOA Lecture 6: Fiber Optic Splices 

Fusion Splicing  

Mechanical Splicing   

Basic splices   (Tutorial)

Mechanical splices

VHO: Mechanical splices

Fusion splices

VHO: single fiber

VHO: ribbon

Book Chapters:
FOA Reference Guide to Fiber Optics,
Chapter 7, Connectors and Splices (same in OSP Book)

FOA CFOT Certification Laboratory Manual,
Fiber Optic Spicing, p40

Student Hands-On Assignments:

Watch the videos and/or read the references and perform the exercises.

Download the Fiber Optic Splicing Worksheet and answer the questions as you complete each exercise.

1. Mechanical Splicing

Video: Mechanical Splicing    VHO: Mechanical splices

Using a mechanical splice, splice two fibers. Use a visual fault locator to optimize the splice. Cleave and repeat several times.

Ultra Splice

2. Fusion Splicing (Single Fiber)

Video: Fusion Splicing   VHO: Single fiber fusion splicing

Using a fusion splicer, splice two fibers and install splice protector. If you can, test with an OTDR. Try the VFL on the fusion splice. Notice the difference between the fusion splice and the mechanical splice when using the VFL.

fusion splicing optical fiber

3. Ribbon Splicing (Mass Fusion Splicing)

VHO: Ribbon fusion splicing

Ribbon (mass) fusion splicing. If you have access to a ribbon splicer and ribbons of fiber, splice those fibers. If you have an OTDR and enough fiber to use it, check your splices with the OTDR. Compare the results of the splices for each fiber in the ribbon.

mass fusion splicing

4. Placing Splices In Splice Trays and Closures

After splicing, place the splices in splice trays and then place the trays in splice closures. There are many types of splice closures, so giving directions is difficult. However, the normal way these are used is the loose tube cable is spliced with one tube per splice tray for each cable being spliced and up to 12 fibers, the normal maximum per tube, spliced in each tray.

splice closures

There are many videos showing the installation practices for splice closures on the web, especially on YouTube. The recommended ones are from manufacturers who are using video to show how to use their products.  We have listed a few below for examples. For more, search YouTube for "fiber optic splice closures" or "fiber optic splicing."

Corning, more    

Preformed Line Products (PLP)   Coyote   

Superior Essex   



Next:  Lesson 5: Fiber Optic Termination (Connectors)           

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Table of Contents: The FOA Reference Guide To Fiber Optics

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