Laboratory Manual

Fiber Optics

Revised September, 2009

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 Laboratory Manual
Hands-on Fiber Optic Training
Section Page
Laboratory Guidelines 3
Safety 4
Fiber Optic Cables 7
Cable Ratings and Markings 13
Zipcord 13
Breakout and Distribution 14
Pulling Cable 18
Double Jacket Loose Tube 18
Loose Tube 19
Armored 20
Fiber Optic Cable Termination 24
Splicing 40
Mechanical Splicing 41
Fusion Splicing 45
Fiber Optic Testing 49
Continuity and Visual Fault Location 51
Visual Inspection with Microscope 52
Optical Power 53
Insertion Loss 57
OTDRs 63

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 Laboratory Guidelines

 Read the “Safety Issues” page FIRST carefully and follow it ! EVERYBODY,
including the instructor(s) must wear safety glasses during all labs and follow
all other safety procedures.

 Make certain before you begin that you understand the purpose of the exercises and
have everything you need.

 Where listed, view the visual aids, especially the step-by-step “virtual hands-on”
exercises” on the FOA Online Reference Website before the lab session.

 Allow plenty of time to complete the exercises, especially termination.

 Clean up after your exercises carefully. Some of the scrap you generate can be
harmful, such as fiber scraps, 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.

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 Safety

Eye Safety
When one speaks of safety in fiber optic installation, the first image that comes to
most people’s minds is a laser burning holes in metal or being used in place of a scapel
for surgery. While these images may be real for their applications, they have no
relevance to fiber optics. Optical sources used in fiber optics are of much lower power
levels and are not focused into a time spot like these applications.
In fact, most data communications links use LEDs or lasers of relatively low
power levels. The light that exits an optical fiber is also spreading out in a cone, so the
farther away from the end of the fiber you are, the lower the amount of power striking a
given sized spot. Furthermore, the light is of a wavelength that cannot penetrate your
eye because of the absorption of the water in your eyeball at those wavelengths.
That said, some fiber optic links, like telco dense wavelength division multiplexing
systems that may contain power from up to 64 different sources and is even amplified
by fiber amplifiers and CATV systems using high-power DFB lasers or optical amps has
enough power to be of concern. Also, using a microscope to inspect an operating
system can be hazardous as the microscope can concentrate the power into your eye.
One should never look directly at the end of a fiber, especially those in working
systems, because the light is infrared and invisible to the eye, so there is no warning of
potential damage. On operating systems, always test the power in the fiber before
inspecting it with a microscope. Many microscopes have filters to remove harmful levels
of infrared light without compromising visibility of fiber defects, but make sure yours has
one before trusting it. Video microscopes are also available to inspect operating
systems safely.
The FOA reference website has a comprehensive discussion of eye safety.
(www.thefoa.org/tech/ref/safety/safe.html) which you and your students should read. A
complete eye safety study and report is in ANSI Z136.2.

Bare Fiber Safety

Fiber optics installation, however, is not without risks. As part of the
termination and splicing process, you will be continually exposed to
small scraps of bare fiber cleaved off the ends of the fibers being
terminated or spliced. These scraps are very dangerous. If they get
into your eyes, they are very hard to flush out. Always wear safety
glasses when working with bare fibers. A pair of safety glasses is
included in the kit. Use them, keep them clean, and protect them
from damage like any other tool.
The cleaved ends are extremely sharp and can easily penetrate your skin! Be
careful to not stick the broken ends into your fingers, since they invariably break off and
are very hard to find and remove. Most times, you have to wait for them to infect and
painfully work themselves out. A pair of tweezers are included in the kit for removing
splinters. Carefully pull the glass splinters out before they have a chance to break off
and become lodged in the skin.

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 Avoid these painful accidents by exercising a little caution. Dispose of all scraps
properly. Keep a piece of double stick tape on the bench to stick them to or put them in
a properly marked paper cup or other container to dispose of later. Do not drop them on
the floor where they will stick in carpets or shoes and be carried elsewhere. Do not eat
anywhere near the work area.

Other Considerations for Safety

Fiber optic splicing and termination use various chemical cleaners and adhesives
as part of the processes. Normal handling procedures for these substances should be
observed. If necessary, download and post MSDS for each substance involved. Even
simple isopropyl alcohol, used as a cleaner, is flammable and should be handled
carefully.

Note: Fusion splicers use an electric arc to make splices, so care must be taken to
insure no flammable gasses are present in the space where fusion splicing is done.

Note: Installation of fiber optic cabling does not normally involve electrical hazards
unless the cable includes conductors. However, these cables are often installed in
proximity to electrical and conductive cables. Whenever you are near these cables,
there is always a potential shock hazard. Be careful! If you are not familiar with electrical
safety, we recommend you take a course on the NEC (National Electrical Code) and
safety practices for installers!

Below is a page of fiber optic safety rules that should be

posted in the lab in a prominent place and reviewed at the
beginning of each lab.

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 Fiber Optic Installation Safety Rules

 Keep all food and beverages out of the work area. If fiber particles are ingested they
can cause internal hemorrhaging.
 Always wear safety glasses with side shields and protective gloves. Treat fiber optic
splinters the same as you would treat glass splinters.

 Keep track of all fiber and cable scraps and dispose of them properly. If available,
wear disposable lab aprons to minimize fiber particles on your clothing. Fiber
particles on your clothing can later get into food, drinks, and/or be ingested by other
means.
 Never look directly into the end of fiber cables – especially with a microscope - until
you are positive that there is no light source at the other end – having tested it with a
power meter. Use a fiber optic power meter to make certain the fiber is dark. When
using an optical tracer or continuity checker, look at the fiber from an angle at least 6
inches away from your eye to determine if the visible light is present..
 Only work in well-ventilated areas.
 Contact lens wearers must not handle their lenses until they have thoroughly
washed their hands.
 Do not touch your eyes while working with fiber optic systems until your hands have
been thoroughly washed.
 Keep all combustible materials safely away from the curing ovens and fusion
splicers.
 Dispose of all scraps properly. Put all fiber scraps in a properly marked container for
disposal.
 Thoroughly clean your work area when you are done.
 Do not smoke while working with fiber optic systems.

For more information on Safety, see the FOA Online Reference Guide / Safety

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 Fiber Optic Cables

What Students Learn:

How to use tools needed for cable preparation, splicing and termination
How to prepare cables for splicing and termination

Exercises:

I. Cable Ratings and Marking

II. Pulling Zipcord
III. Break-out and Distribution Cables
a. Preparing Breakout Cable for Termination
b. Preparing Distribution Cable for Termination or Pulling
IV. Handling and Stripping the Fiber
V. Preparing Distribution Cable for Pulling
VI. Pulling Cable
VII. Dual Jacket Outside Plant Cable
VIII. Preparing Single Jacket Loose Tube Cable
IX. Preparing Armored Cable

Note: This manual includes instructions for a number of cable types. You may not have
all these available, but as a minimum, you should try to use 3mm jacketed tight buffer,
distribution, breakout and loose tube cables samples for training.

Visual Aids
The following visual aids show the processes described in these exercises. They
may be shown to the students before the lab or just used as a reference by the
instructor.
FOA PPTs, Cables
FOA Online Reference Guide To Fiber Optics: Basics/Cables, Cable VHO
FOA Instructional Videos (Online or DVD): Cable Preparation

Safety:
All students and instructors must wear safety glasses in this lab. Follow all safety
rules for working with fiber. Safely dispose of all fiber and cable scraps after use.

Tools and Materials needed:

Safety Glasses
Miller Jacket stripper
Aramid Yarn Scissors
Needle Nose Pliers
Armored Cable Cutter
Large Jacket Slitter and Stripper
Fiber Optic Stripper
Utility Knife
Cable Pulling eye, tape,

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Sample Cable types: Simplex, zipcord,
distribution, breakout, loose tube and
armored, gel-filled loose tube

Tools:

Large Jacket Slitter and Stripper

The Cable Slitter and Stripper can be used to cut and slit jacket on cable with an
outside diameter of up to 2.75in. The blade is adjustable for jacket thickness’ up to
0.187in.. The blade can be turned 90 degrees for an axial cut, left in its normal position
set for a round cut or changed to a ‘in between’ angle for a spiral cut. A spare blade is
stored in the handle.

Small Cable Stripper

This light weight stripper will make round or axial cuts on small cable jackets and
buffer tubes quickly and easily. The adjustable blades can be set to any depth from
1/8in. to 7/32in. (3.175mm to 5.556mm) to assure nick-free strips. Each stripper comes
complete with one round and three straight blades.

Adjustable Jacket Stripper & Cutter

The adjustable jacket stripper strips and cuts various sizes of fiber optic cable
jackets, primarily 3mm jacketed simplex cable or small distribution cable. The numbered
eight-sided cam easily and accurately adjusts to fit different sized cable. All cutting

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surfaces are precision formed, hardened, tempered, and ground assuring clean, smooth
strips.

Fiber Optic Buffer Stripper

This Fiber Optic Stripper is used for buffer (primary buffer coating) removal
without any scratching or nicking of the optical fiber. The stripper is designed for
stripping 250 micron buffer coating from 125 micron optical fiber. It is commonly called a
“Miller Stripper” after the largest manufacturer. Other types of buffer strippers are the
“No-Nik” (center) and “Micro Strip (right).”

Needle Nose Pliers

Extra long needle nose pliers are excellent at grabbing and pulling pullcords, or
ripcords. Grab the pullcord firmly with the pliers, roll the cord around the jaws, and pull
back along the cable to slit the cable open. Do not pull at 90 degrees to the cable. This
will break the pullcord.

Aramid Yarn Scissors

Super-sharp scissors are specially made for cutting the tough Kevlar fibers used
as strength members in fiber optic cable. They are made from hard stainless steel or
ceramic to stand up to repeated use on Kevlar fibers. These scissors should be used
only for cutting aramid yarn (Kevlar).
To use, bunch all the aramid yarn together, twist into a rope and cut all the fibers
at once. The cutters should cut through in 1 to 2 snips.

Armored Cable Cutter

A standard plumbing tubing cutter can be used with larger diameter metallic-
armored cables for cutting through both outside jacket and armor. The depth of the
cutting blade is generally correct for cutting the outer jacke and armor without harming
the inner jack or fibers in an metallic-armored cable. Cut the armor just like tubing,
making several revolutions around the cable, tightening the cutters with each revolution.

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Fiber Optic Cable Preparation

These exercises will show you how to handle fiber optic cables during
installation, splicing and termination.

Refer to the toolbox manual for tool and instrument instructions.

Pulling Cable
In a classroom course, we cannot have you practice “pulling” cables. The main
thing to learn is that cable must be pulled ONLY by the strength members provided in
the cables, never by the fibers and only special cables can be pulled by the jacket.
If you are ever in doubt about the proper way to pull a specific type of cable,
contact an applications engineer at the cable company and get specific instructions.
Otherwise you may damage the fibers. Damage to a fiber optic cable is never
reversible. If it is damaged, it must be removed and replaced, potentially very
expensive!

Preparing Cables for Termination and Splicing

In this course, we describer the use of several common types of cable for
practice. These cables are tight buffer, distribution, breakout and loose tube cable
typical of cables installed in a network. You use these samples to strip jackets and
expose fibers for splicing or termination. Refer to the Toolbox instruction sheets for the
tools you will be using.
After working with the samples provided, fill in the worksheet at the end of the
section.

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 Pre-Lab Cable Preparation

Note: Securing ripcords when using short lengths of cable.

In order to successfully complete the cable exercises that include using the cable’s rip-
cord, an additional preparation step may be required. There may not be enough friction
in the short length of cable to hold the ripcord in the cable. When the rip-cord is used to
cut the cable jacket or armor, it may instead be pulled right out of the cable. To avoid
this and to insure that the rip cord does its job the following steps must be done prior to
the exercises.

Follow the procedures in sections VII and XI of the Fiber Optic Cable Hands-On section
for specific instruction on removing the jackets. (see also, the Toolbox Manual for round
cable slitter and armored cable cutter instructions)

Wear Safety Glasses for this exercise!!

1. Remove approximately 3 inches of the outer jacket. Expose ripcords. Do Not

damage the exposed rip cords.

2. Locate inner ripcord (if any). If there is no inner ripcord, strand together a few Kevlar
fibers and hold them aside with the rip cords.

strength member/Kevlar
cabl
e fibers

ripcords

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3. Cut off all fiber and strength member close to the cable end. Do Not damage the
exposed ripcords.

4. Tie all the ripcords together.

ripcord knot
s s

5. Tightly tape the ends of the ripcords back along the cable with black electrical tape.

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I. Cable Ratings and Markings

All indoor cables must carry identification and ratings per the NEC (National
Electrical Code). Cables without markings should never be installed as they will not
pass code inspections! Examine some indoor cables to see the markings.

These ratings are:

OFN optical fiber non-conductive
OFC optical fiber conductive
OFNR or OFCR riser rated cable for vertical runs
OFNP or OFCP plenum rated cables for installation in air-handling plenums
OFNG or OFCG general purpose
OFN-LS low smoke density

Stop now and fill in the exercise worksheet.

II. Pulling Zipcord

All fiber optic cable must be pulled by the strength members, since that’s how
they are designed to withstand pulling tension.
There is a simple exercise to see why you do not pull fiber optic cable by the
jacket. Use a 2 m (6’) length of zipcord. Have two students grab each end by the jackets
(don’t wrap around the hand) and pull as hard as they can. The jacket will stretch and, if
pulled hard enough, break. Release the tension and watch the jacket shrink back on the
cable. The fibers and strength members will bunch up inside the cable causing a lumpy
texture to the cables. The constriction of the fibers will cause extremely high loss and
stress that may cause eventual failure. Cables should always be pulled with pulling eyes
attached to the strength members.
If you are going to be pulling lots of zipcord or small fiber count cable indoors,
you may want to make a pulling mandrel. It requires a round mandrel about 8-12” in
diameter like a cable spool and two handles available from any hardware store.

Pulling cables properly is done with a swivel pulling eye. Following the instructions,
attach the supplied swivel pulling eye to the zipcord cable.
1. Split the Zipcord cable into two single fiber cables.
2. Using the Miller jacket stripper, strip off the jacket exposing the Kevlar (a duPont
trade name for aramid fiber) strength members and the buffered fibers.
3. Cut off the fibers close to the jacket end.
4. Tie the strength member to one end of the swivel pulling eye
5. Tape the strength member to the cable jacket to secure the eye.

Stop now and fill in the exercise worksheet.

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III. Breakout and Distribution Cables

Two common cables are breakout cables and distribution cables. Breakout
cables consist of a number of single fiber sub-cables made into a larger cable
assembly. Each sub-cable has a buffered fiber surrounded by Kevlar strength members
and a plastic jacket that can be terminated by a standard connector. The sub-cables are
wound around a central strength member, which also acts as a bend radius limiter.
The big advantage of the breakout cable is that it can be brought to a termination
point, have the jacket stripped off and individual sub-cables terminated directly. Then
the sub-cables can be connected to patchpanels or terminal equipment with no further
hardware. The easier termination at the ends makes breakout cable very cost effective
in many building applications. The disadvantage of the breakout cable is its cost and
size. For longer runs, it may not be the best choice.
Pulling breakout cable requires more care also, due to it’s more complex
construction and larger size. It is usually pulled by stripping the Kevlar strength
members from each sub-cable and cutting off all the fibers, then tying the Kevlar
strength members to a pulling eye that is firmly attached to the central strength member.
In some cases a jacket gripper (“Kellum’s Grip”) is used in conjunction with the pulling
eye. Consult the cable manufacturer for special instructions for longer pulls on breakout
cable.
Distribution or tight-pack cables are designed for use in dry conduit or short riser
applications. It consists of a bundle of 900 micron buffered fibers with a central
stiffener/strength member, a wrapping of Kevlar strength members, and a outer jacket.
Distribution cables are much smaller and lighter than breakout cables, but the individual
buffered fibers require termination inside a patch panel or junction box or sleeving each
of the individual fibers in a breakout kit before termination.
Combinations of the two design can be made for some applications. For
example, a number of smaller distribution cables can be combined into a breakout
cable. At some point, the breakout cable jacket can be stripped and the individual
distribution cables pulled to separate locations.

Stop now and fill in the exercise worksheet.

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A. Preparing Breakout Cable for Termination

To prepare the breakout cable for termination, we will first use the jacket stripping
tool and remove the jacket of the cable.

1. Viewing the end of the cable, confirm the outside jacket is round and uniform.
2. Hold the jacket slitter up to the cable jacket and use the knurled nut to set the blade
depth to approximately 80-90% of the thickness of the cable jacket. You don’t want
to cut through the jacket as you might damage the cables inside.
3. Make a trial cut of the jacket about 3-4 inches back from the end to see if the cutting
depth is correct.
4. Place the slitter on the cable and make several turns around the cable. Don’t force
anything, the tool’s spring tension will cut the jacket gently.
5. Remove the tool.
6. With your thumb under the cable to limit the bending, bend the cable until the jacket
snaps.
7. Turn the cable over and repeat the bend on the opposite side so the jacket is
completely snapped.
8. Pull the jacket off the end of the cable.

If the jacket slitter worked correctly, you now have about 4 inches of sub-cables,
a strength member and a “pull string” or “ripcord” sticking out of the end of the jacket.
Use the ripcord to slit the jacket to about 2 feet back from the end.

1. Use the needle-nosed pliers to grip the ripcord.

2. Coil the ripcord around the jaws of the pliers.
3. Pull gently back along the cable to slit the jacket. Do not pull at 90 deg to the fiber.

Use the jacket slitter to cut the jacket just beyond where the jacket was slit by the
ripcord and remove the section of jacket. If there is a central strength member, cut it off,
leaving only enough to tie off or clamp. Now you have two feet of sub-cables ready to
prepare for termination.
The individual sub-cables should have their jacket stripped, Kevlar strength
member cut to the proper length and the fiber stripped as specified by the manufacturer
or the connector being installed.

Stop now and fill in the exercise worksheet.

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B. Preparing Distribution Cable for Termination or Pulling

Distribution cable consists of a central strength member, bundles of buffered

fibers, Kevlar fiber strength members wound around the fibers and an outer jacket. It is
very important when cutting the jacket with the cable slitter that you do not cut through
the jacket, as the fibers are simply bundled inside and may be nicked by the slitter
blade.

Using a sample of distribution cable, prepare the cable as follows.

1. Verify the blade depth of the cable slitter by checking it against the jacket at the end
of the cable.
2. Make a trial cut a few inches back from the end to make sure the blade depth is
correct.
3. Since the jacket on distribution cable is not tightly bound, you do not have to use the
ripcord to slit the jacket, although you may.
4. Cut the jacket about 18 inches back from the end.
5. Break the jacket over your thumb and pull the jacket off the cable.
6. Unwind the Kevlar strength members. It is probably counter-wound, so you may
want to push back the Kevlar, cut to the length needed (about 10-12 inches to attach
a pulling eye, less for tying off at a junction box.)
7. Remove the binder tape that holds the bundles of fibers together.
8. Identify the central member, unfold the fibers wrapped around it.
9. For termination, cut the central member off at a length necessary for clamping or
tying off.
10. For pulling the cable, cut off the central strength member and all the fiber, then
attach a pulling eye to the Kevlar strength members.

Stop now and fill in the exercise worksheet.

IV. Handling and Stripping The Fiber

Wear Safety Glasses for this exercise!!

It is important when preparing the cable to determine how easily the fiber can be
stripped. If possible get a sample of the buffered fibers used by the manufacturer to test.
The time it takes to strip the fiber will affect the time and cost of the installation job.
Take a piece of the fiber from the distribution cable and try stripping it using the
following guidelines.

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IV. Handling and Stripping the Fiber

Wear Safety Glasses for this exercise!!

1. Do not use your finger to feel for the fiber ends. You can stick the fiber into your
finger and it will usually break off in your finger, producing a painful experience!
2. Always wear safety glasses when working with fibers, to prevent getting fiber pieces
in your eye. It is very hard to remove and very painful!
3. To hold the fiber for stripping, hold it between your fingers, wrap it between your
fingers in a zig-zag fashion or wrap it around your palm.
4. Do not bend the fiber in a small radius. Fiber is very strong in tension but breaks
easily over sharp edges.
5. Use the Miller stripper to carefully remove the buffer coating and expose the fiber.

Stop now and fill in the exercise worksheet.

V. Preparing Distribution Cable for Pulling

Using the distribution cable you have already prepared for pulling, attach a
pulling eye.

1. Twist the Kevlar fiber to make it look like yarn and tie a knot in the end to facilitate
handling.
2. Use the swivel provided in the toolbox.
3. Tie the swivel to the strength member about two inches from the end of the cable
with two half-hitches.
4. Pull the Kevlar back over the cable and cut so it overlaps the jacket by about one
inch.
5. Tape the Kevlar over with electrician’s tape.
6. Make sure there are no rough edges that can snag on the conduit during the pull.

The swivel is now ready to tie to the pulling rope.

Stop now and fill in the exercise worksheet.

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VI. Pulling Cable

On long cable runs, it may be preferable to pull the cable from a central point
towards both ends. Since it is very important to not put twists in the cable, the cable
should be laid out on the ground in a “figure 8” pattern. The figure 8 puts a half-twist in
the fiber one way, then takes it out on the other half of the “8”, preventing twists.
Indoor runs should be pulled without lubricants if possible, due to the mess they
can make in a building. Long runs or difficult pulls should use lubricants. (An excellent
video on lubricants for pulling is available from American Polywater, Box 53, Stillwater,
MN 55082. 612-430-2270 or fax 612-430-3634, polywater.com)
If a pull needs some leverage but not enough to require power pulling equipment,
you can use a cable reel, two folding chairs and a piece of conduit to form a large
version of the mandrel puller shown earlier. The cable itself will withstand up to 600
pounds of pulling force. By winding the pulling rope on the cable reel first, the reel will
be pulling on the strength member of the cable, not the jacket, and several hundreds of
pounds of force can be exerted safely (for both the cable and the installers!)

Stop now and fill in the exercise worksheet.

VII. Preparing Dual Jacket Outside Plant Cable

Outside plant cable is usually loose tube cable with strong dual jackets or
armoring. This cable has a jacket that is strong enough that it can be pulled directly by
the jacket using a Kellum’s grip. Duct cable will be installed in conduit, aerial cable may
have an internal strength member or require being wrapped to a messenger wire. Direct
burial cable is often armored with a thin layer of metal to prevent rodent damage.

A. Preparing Dual Jacket Duct Cable

Dual jacket duct cable has two jackets with an Kevlar strength member between
the two jackets. The strength member is bonded to the jackets so it can be pulled by a
Kellums grip directly on the jacket. Since the strength members are contrahelically
wound (two helical windings in opposite directions, overlapping), a rip cord will not work
on this cable, so it is necessary to cut both jackets and the strength member at once
with the cable slitter.

1. Inspect the jackets for concentricity,(equal thickness all the way around).
2. Set the cable slitter blade depth to cut both jackets.
3. Take a test cut about 4 inches from the end of the cable.
4. After cutting with the slitter for several rotations, push down hard on the slitter’s
cable retention bar to make sure it is cutting through the Kevlar strength member
and the inner jacket.
5. Break the jacket with your thumb under it.

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6. Pull the cut jackets off. It will be difficult due to all the materials in the cable. After
pulling it a small amount, push the jacket back and the Kevlar can be cut with the
scissors, making it easier to pull off.
7. To cut off a longer piece of the jacket to expose fibers for splicing, use the cable
slitter to slit the jackets on both sides. Use the lever on the slitter to rotate the blade
for slitting.

Stop now and fill in the exercise worksheet.

VIII. Preparing Single Jacket Loose Tube Cable

Loose tube cable is usually gel filled to protect the fibers from moisture or water.
A single jacket cable cannot be pulled on the jacket, so it is important to separate the
strength members if it is being prepared for pulling. In this case, we will see a cable
prepared for termination or splicing.
It is recommended you work over a clean work surface with disposable paper, as
the gel is messy!

1. Inspect the jackets for concentricity.

2. Set the cable slitter blade depth to cut both jackets.
3. Take a test cut about 4 inches from the end of the cable.
4. Slide off jacket.
5. Find the ripcord and use it to slit the jacket several feet back (as long as you need
for fiber splicing or termination.)
6. Use the cable slitter to cut the jacket at the end of the slit and peel off the jacket.
7. You now have a “gooey mess” which can be cleaned with commercially available gel
cleaners in wipe form.
8. Peel off the Kevlar strength members, which can be cut to the proper length for
attaching to a pulling eye or tying the cable off.
9. Remove the binding tape.
10. Separate the loose tubes that contain the fibers and the central strength member.
11. Cut the central strength member off at the proper length.
12. Clean the tubes where you plan to cut them. The length will be determined by the
hardware you are using for splicing or termination.

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13. You can cut the buffer tubes by scoring them with the tubing cutter. Let the cutter
work on its own - do not force it.
14. Feel where the tube is scored, place your thumb under it and gently snap the tube.
15. Pull the tube off, exposing the fibers.
16. Wipe the gel off the fibers.

Now you are ready to splice or terminate the fibers. Make sure you know which
hardware you will be using so you can cut the tubes to the proper lengths.

Stop now and fill in the exercise worksheet.

IX. Preparing Armored Cable

Armored cable has a thin metal layer between two jackets for protection against
rodent penetration in direct burial installation. The outer jacket and armor are generally
thin enough that once a small part is removed, a rip cord can be used to split the armor
and outside jacket for easy removal. The armor is too hard to cut with a normal cable
slitter, so a regular plumbing tubing cutter is used. The tubing cutter blade cuts about
1/8th inch deep, ideal for cutting the outer jacket and armoring without harming the inner
jacket and fiber.
Use a sample armored cable to practice removing the outer jacket and armor:

1. Using the armored cable cutter, make a cut about 4 inches in from the end.
2. Keep tightening the cutter just until the shoulder of the cutter reaches the jacket and
the cutting blade has penetrated to the full depth. It is not advisable to tighten the
cutter any further as it cannot penetrate further and will merely flatten the cable.
3. Remove the cutter.
4. Flex the cable to finish breaking the outer jacket and armor.
5. Slide the short section of outer jacket and armor off the end.
6. Use the ripcord to slit the jacket. With the needle-nosed pliers, roll the ripcord around
the jaws of the pliers to begin cutting through the jacket and armor.
7. Pull the ripcord back along the jacket of the cable to rip the armor and jacket.
8. Repeat with the other ripcord to finish slitting the armor and jacket.
9. Use the armored cable cutter to cut through the jacket and armor just beyond the
end of the slit.
10. Pull off the slit armor and jacket segments.

The inner cable can now be handled just like any other cable for termination and
splicing.

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 Fiber Optic Cables Worksheet

Name:________________________________

I. Zipcord & Pulling

1. All cables should be pulled ONLY by the __________________________.
2. What is the most obvious sign of cable damage due to incorrect pulling?
_______________________________________________________
3. Can you just cut the cable, make a loop on the end and pull by that loop? Explain.
__________________________________________________________________
4. What can you check to make sure the installer pulled the cable correctly?
____________________________________________________________

II. Cable Marking

1. What does the marking OFNR mean? Where can it be installed?
_______________________________________________________________
2. What defines the requirements for fire retardency of cables?
____________________________________________________________

III. Breakout and Distribution Cable

1. What is the biggest advantage of breakout cable?
________________________________________________________
2. On a breakout cable, where does the NEC or UL marking appear?
________________________________________________________
3. If space is limited, would breakout or distribution cable be preferred?
__________________________________________________________

III. Breakout Cable

1. How deep should the jacket slitter blade cut into the jacket?
__________________________________________________
2. Why do you make a “trial cut” of the jacket near the end of the cable?
_____________________________________________________
3. What tool do you use to pull the ripcord?
___________________________________________________
4. Once the sub-cables are exposed, what else must be done to them to install
connectors? ___________________________________________________

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IV. Fiber Handling and Stripping
1. What should you do to handle fiber safely?
_______________________________________________________
2. What causes fibers to break ?
______________________________________________________

V. Distribution Cable
1. What do you want to pull on when pulling distribution cable?
___________________________________________________________
2. Where can you get swivel eyes?
__________________________________________________________
3. How close should the swivel be to the end of the cable?
__________________________________________________________

VI. Cable Pulling

1. Why do you “figure 8” cable?
___________________________________________________
2. How much pulling strength does the cable have ?
____________________________________________________
3. What is the cable reel pulling on?
____________________________________________________

VII. Dual Jacket Outside Plant Cable

1. What can you do with dual jacket outside plant cable that you should not do with
most cables?
_______________________________________________________________

2. Why can’t you use a ripcord with dual jacket outside plant cable?
_______________________________________________________________

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VIII. Single Jacket Loose Tube Cable
1. Why do loose tube cables have gel filling ?
______________________________________________________________

2. How do you cut the tubes without breaking the fibers?

_______________________________________________________________

3. How long should the buffer tubes be after cutting?

_______________________________________________________________

IX. Armored Cable

1. Where is armored cable usually placed?
_______________________________________________________________

2. Why does the cable have armor ?

_______________________________________________________________

3. Why do you need zipcords with armored cable?

_______________________________________________________________

836700932.doc, 1/22/25, 23
 Fiber Optic Cable Termination

What Students Learn:

How to prepare cables for termination
How to terminate fibers in basic adhesive/polish connectors
How to inspect polished connectors
How to test connectors for insertion loss

Exercises:
I. Cable Preparation
II. Fiber Preparation
III. Epoxy Preparation
IV. Connecterization
V. Cleaving
VI. Polishing Multimode Connectors
VIII. Testing the Patchcord
A. Continuity
B. Microscope Viewing
C. Loss Testing
1. Single-ended test
2. Double-ended test
IX. Terminating Buffered Fiber

Visual Aids
The following visual aids show the processes described in these exercises. They
may be shown to the students before the lab or just used as a reference by the
instructor.
FOA PPTs, Termination, ( sections on epoxy, anaerobic, HotMelt,
prepolished/splice and singlemode as appropirate)
FOA Instructional Videos (Online or DVD): Termination
FOA Online Reference Guide To Fiber Optics: Basics/Cables, Termination
VHOs (epoxy, anaerobic, HotMelt, prepolished/splice and singlemode as
appropirate)

Safety:
All students and instructors must wear safety glasses in this lab.
Follow all safety rules for working with fiber.
Safely dispose of all fiber scraps and cables after use.

836700932.doc, 1/22/25, 24
Materials Needed:

Fiber Optic Stripper

Crimp Tool
Polishing puck
Aramid Yarn Scissors
Scribe
Miller Jacket Stripper
Cable: 3 mm jacketed fiber optic cable, 1-2 m (3-6 ft)
6 ST or SC connectors (connector, crimp sleeve, and strain relief boot),
Adhesive, Epoxy, 2 syringes, Curing Oven or Anaerobic (Loctite 648)
Curing over for epoxy or HotMelt connectors
Wipes
Polishing Film films (12, 3 and 0.3 micron)
Polishing Plate (Glass or plastic) and Rubber Pad
Microscope with ST, SC or universal stage
3 mm jacketed fiber optic cable, 1-2 m (3-6 ft)

Fiber Optic Cable Termination

Before starting this session, review the process at the Virtual Hands-on
Termination Session on the FOA Online Reference Guide and/or view the video
on Termination or the sections in the Termination PPT
In this lab, we will terminate fiber optic cables using ST or SC style connectors of
adhesive/polish type, typically the “epoxy and polish” type. This is the most basic type of
termination and most widely used, due to its low cost. Other types include
“anaerobic/polish”, “HotMelt” or “anaerobic” adhesives will be described also. All types
use adhesive to hold the fiber and are polished to get a good optical finish for mating to
another connector.
Once you know how to terminate with this type, you can easily follow the
instructions for any other type. Prepolished/splice connectors are becoming more
popular in the field but are expensive to teach. Use the Termination PPT section on
them to review the process with students.

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Fiber Optic Connector Termination

It was not long ago that the proper methods used to terminate fiber optic
connectors were tedious and the labor involved was a big concern. However in the last
decade, manufacturers have developed new types of cable, connectors and methods
that make fiber termination as easy as copper terminations.
Some of the old methods are still in practice today. Progressive installers have
been fast to accept much of these new products and procedures. It has been the
development of these newer products and techniques that has led to the accelerated
use of fiber in the marketplace.
In this section we will examine the most common methods of fiber optic
connector termination used in the field, epoxy/polish. (The next most common types
are anaerobic adhesive, HotMelt and prepolished/splice. Please note that the points
examined here are generic in nature and will vary somewhat from manufacturer to
manufacturer.)

We cannot stress enough the importance of following the manufacturers specific

instructions for each type of connector.

We will start each section with a review of the necessary tools. Each connector
type will have a set of tools specific to that connector, but the Toolbox contains tools
that will work with most epoxy/polish connectors of ST, SC and FC styles. You will
practice termination with a 3 mm jacketed cable, but working with most multifiber cables
will be similar, although the strength members may have different uses.

In each type of connector there are three procedures to follow:

1. Prep the cable to be terminated and assemble the connector on to the cable.
2. Scribe and polish the assembled connector.
3. Inspect the final product.

Some connectors are three part (connector, crimp sleeve and strain relief, while
others are two part (connector and strain relief). The actual connectors you use should
have specific instrructions on how to terminate them, so follow them exactly. The
following instructions refer to a standard 3 part ST connector.
The polishing part is basically the same for each application and each cable type.
The termination procedure is also the same with regard to cable type regardless of the
connector type.

Work in a clean workplace - dirt and dust are the worst enemies of good
terminations!

836700932.doc, 1/22/25, 26
 A black work mat will make it easier to see fibers during the termination process
and when cleaning up.

Cut off about 4-6 feet of a 3mm jacketed cable or remove a length of buffered fiber from
a distribution cable in the Fiber Optic Cables section.

Preparation: All tools should be laid out on the lab table in an orderly fashion. Check at
this time to make sure that you are not missing anything.

Clockwise from left: 3 mm jacketed cable, connector curing oven, epoxy, polishing plate,
wipes, trash bin, crimper, Kevlar scissors, jacket stripper, fiber stripper, instructions and
stripping guide.

Fiber Optic Crimp Tool

The crimp tool provides the proper compression force on the crimp sleeve
required to insure retention of the connector on the cable. The ratcheting action
assuring a proper crimp each time.
If the ring and connector are not secure on the cable after crimping, check for
undersize outside diameter of the cable. Never Re-Crimp in a smaller hex die opening.
This may damage the tool.

836700932.doc, 1/22/25, 27
 Wrong Crimp
Correct Crimp
(Over-sized Ring)

If the finished crimp looks like the one pictured above right, an over sized crimp
ring was used. Completing the crimp may damage the tool. Check with the connector
manufacturer for the proper crimp ring size.

Scribe

The scribe is a sharp, hard crystal that is used to scratch or scribe the fiber for cleaving.
It is used in termination to remove the excess fiber from the connector ferrule before
polishing.

Polishing Plate, Pad and Puck

One needs a flat hard plate as a polishing surface for the connector. Most connectors
are PC or physical contact types, so the end of the ferrule is convex. They should be
polished on a 1/8 inch (3mm) rubber pad placed on top of the plate or multiple layers of
old polishing film. A polishing puck or fixture is used to hold the connector perpendicular
to the plate during the polishing process.

Applying Adhesives
Epoxy is normally supplied in a “bipax” of epoxy and hardener. When ready to
use, mix by removing the center divider and working the two liquids inside the bipax with
your fingers or on a hard surface. When fully mixed, cut one corner to create a small (3
mm, 1/8”) opening. Attach a square tip needle to the syringe and remove the plunger
from the syringe. Carefully squeeze the adhesive into the syringe. Just start the plunger
into the syringe, then hold needle up long enough to let the epoxy run down to the
bottom, then squeeze the air out of the syringe. You now have about 30 minutes of

836700932.doc, 1/22/25, 28
working time to use the epoxy, long enough to share among all students in a class, so
the instructor can be responsible for the adhesive.

The epoxy is applied by injecting a small amount into the connector until a bead
appears on the end of the connector, then the needle is pulled back slightly and more
epoxy injected into the body of the connector.

Anaerobic adhesives do not require mixing. The recommended adhesive, Loctite

648, comes in a dropper bottle that can be simply wiped along a fiber that has been
stripped and cleaned, and then the fiber is inserted in the connector.

HotMelt connectors already have adhesive – a hot melt adhesive – in the

connector. The connectors are placed in an oven to melt the adhesive to allow inserting
the fiber, then allowed to cool to set the adhesive.

836700932.doc, 1/22/25, 29
I. Cable Preparation
3mm jacketed cable

1. Open the connector package in front of you and take out the parts. If the area is very
dusty do not let the connector fall into the dust as this may clog the fiber hole. Also the
connector should have a dust cap on the ferrule. Do not take it off until you are ready to
install the connector.

2. On each cable end place a strain relief boot with the small side first.

3. Next place the crimp sleeve on the cable. It will be used to clamp on the Kevlar
strength member of the cable and hold the strain relief boot to the connector after
assembly.

Your assembly should look as below.

Strain Relief Boot Crimp Sleeve

4. Use the jacket strip tool to strip back the jacket of the cable exposing the needed
length of buffered fiber, about 2 inches. This also exposes the Kevlar strength member
of the cable. Use the #4 flat on the Miller stripper for 3mm jacket cable.

5. Using the scissors made to cut Kevlar provided in the Toolbox, cut back the Kevlar
strength members,(leaving about 3/8 inch).

NOTE: Connector manufacturers will specify the exact dimensions needed for
stripping cable for their connectors. Ensure you have the proper information
before trying to terminate that connector.

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II. Fiber Preparation

Wear Safety Glasses for this exercise!!

This part will take a bit of practice but as in all things just go step by step. We will
proceed to connectorize one fiber at a time

1. Take your buffer strip tool and strip off from .75" to 1.0 inch of buffer material from
the fiber. Be careful that there is no debris in the tool jaws as it will cause the fiber to
break. Some buffer materials adhere to the glass fiber tighter than others. It is
advised that you take off short strips of about 1/8” to 1/4” at a time. Do not clamp
squarely down on the fiber. This will bend and kink the fiber. Hold the tool at a
steady angle to the fiber and pull buffer slowly and steadily down the fiber. (You
may want to practice this step 5-6 times before mixing the epoxy)

Stripping Guide for 3 piece connectors with separate crimp ring:

1 3/4”
3/4”
3/8”

Kevlar
Outer Jacket Buffer
Optical Fiber

Stripping Guide for 2 piece connectors with integral crimp ring:

2. There may be some debris left on the fiber after stripping. Take a clean lint-free wipe
dabbed with a little alcohol and wipe the fiber clean.

Note: Do not use rubbing alcohol as it is mostly water and may prevent adhesive
setting or affect its cured strength and reliability. Use 99% lab grade isopropyl
alcohol ONLY.

836700932.doc, 1/22/25, 31
III. Epoxy Preparation

1. Take the package of epoxy and remove the two part mix from the package. You will
notice that there are two parts with a divider. Remove the divider. Mix the two halves
together. If you do not have a tool designed specifically for mixing, such as a roller, the
divider may be used. It is extremely important that you completely mix both halves
together or the adhesive will not cure 100%.
2. Having mixed the epoxy completely take the empty syringe with needle attached and
pull out the plunger. Be careful not to let the plunger roll in any dust.
3. Clip off one corner of the mixed epoxy pack and pour the mixture into the syringe.
When the syringe is full place the plunger back in the syringe.
4. NOTE! Only place the plunger back in the syringe a very little bit as it will be full of
air. Hold the syringe up side down and let the epoxy run down to the back of the
syringe. When the epoxy runs down all the way you can push the plunger all the way
forward removing the air.

NOTE! your epoxy has a working time of 20 to 30 minutes.

Other adhesives:

Anaerobic adhesives are quick-setting one- or two-part adhesives that do not require a
heat cure. Anaerobic adhesives do not require mixing. The recommended adhesive,
Loctite 648, comes in a dropper bottle that can be simply wiped along a fiber that has
been stripped and cleaned, and then the fiber is inserted in the connector.

3M Hotmelt: 3M offers a heat setting adhesive that you heat the connector up to soften
the adhesive, insert the stripped fiber and let it cool before polishing. Information and
videos are available from 3M. Note that HotMelt connectors use a much hotter oven
than heat-cured epoxy. An epoxy oven will not soften the adhesive in HotMelt
Connectors and a HotMelt oven will overheat and ruin epoxy!

836700932.doc, 1/22/25, 32
IV. Attaching the Connector

Wear Safety Glasses for this exercise!!

1. Remove the dust cap on the connector ferrule.

2. From the back of the connector body inject the connector with the epoxy. Make sure
that the needle of the syringe is inside the connector body as far as it will go. Use light
pressure on the plunger as you inject the epoxy until you see a small bead of the
adhesive emerge from the ferrule tip. This bead will help hold the fiber during the
cleaving process and ensure the proper cleave.
Remove the syringe from the connector half way and continue to fill the connector until
epoxy appears from the end of the connector. Remove the syringe from the connector
and pull back on the plunger to prevent any adhesive from coming out of the needle.

3. Insert the stripped fiber through the back of the body of the connector towards the
ferrule. Use a twisting motion on the connector to aid the glass fiber in finding the hole
in the ferrule. Push the fiber in as far as it will go.

4. Move the crimp sleeve up over the back of the connector body, capturing the Kevlar,
and crimp it to the body using the recommended crimp tool.

5 Place the strain relief boot over the back body of the connector.

6. Place the special protective sleeve provided over the ferrule of the connector, making
sure not to break off the fiber and set it aside for overnight curing. This is to protect the
fiber from breaking while you handle it before polishing and while curing.

After you have successfully attached a connector to one end of the cable, do the same
for the other end. If you have taken longer than 20 minutes, the epoxy will have
hardened too much for use. You should wait until you polish your connector and then
terminate the other end in another session to make a patchcord which you can test.

Leave the cable assembly in a safe place to cure overnight or cure for the
recommended curing time in an oven!

836700932.doc, 1/22/25, 33
V. Cleaving
After oven or overnight curing:

Wear Safety Glasses for this exercise!!

1. Take your scribe tool and scribe the glass using light pressure so as not to break off
the glass fiber from each connector. 2 or 3 scratches is enough.

2. Remove the glass by pulling both up and away as in figure 9.

Pull

Scribe here

3. You are now ready to polish the connector ferrule.

VI. Polishing for Multimode Connectors

Polishing fiber optic connectors in the field is to some extent an art form. So it
takes a “few tricks of the trade” so to speak to make it a clean and easy process. The
operative word here is clean. This is the most important factor.

Note: Singlemode technology is used in a lot of data rated applications. In these

situations concerns over insertion loss are minimized and there is little concern over
return loss. In these situations it is perfectly acceptable to treat a singlemode connector
with a multimode polish. When concerns over return loss are present we change our
polishing technique to accommodate it.

Multimode polishing:
Lay your tools in front of you in an orderly fashion. You should have the glass
plate, lapping films, polishing tool, and lint-free wipes.

1. Lay the 3 micron (yellow) and 0.3 (white) micron on the glass plate. Note that some
films are adhesive backed. Make a double layer of these to create a softer surface.

2. Take the 15 micron (pink) film and one of the connectors to be polished. Hold the
connector upright and the film with the grit facing down. With very light pressure polish
the face of the connector so as only to take down the glass burr that remains from the
scribe step.

836700932.doc, 1/22/25, 34
3. Now observe the adhesive bead. Polish this down until it is a thin layer but not
completely gone.

Note: When you are doing an epoxyless connector with a stainless ferrule, polish the
fiber down to the metal tip.

4. Place your connector in the polishing puck. Lay it down gently on the 3 micron
lapping film, one side first. Do not slam it down hard as you could shatter the fiber.
Using a figure 8 motion polish the connector until the adhesive bead is gone. If you are
polishing a ceramic connector you will notice that the connector gets slippery on the
plate. Stop polishing instantly. Now go to the 0.3 micron film With the same motion, go
only one or two figure 8's. Your connector is done.

Note: With a ceramic connector, you should use almost no pressure at all on the
connector as you polish. With a stainless connector you will want a moderate amount of
pressure of about two to three pounds.

5. Remove the connector from the polishing puck and wipe off the sides of the ferrule
and the face of the ferrule to remove any dust and debris.

836700932.doc, 1/22/25, 35
VII. Testing the Patchcord

After you have terminated both ends of a cable, you can test it to see how good
your connectors are. Follow the procedure you learned in the Testing hands-on session
and fill in the worksheet.

A. Continuity Test
Using the Visible fiber tracer, test your cable to make sure it is continuous. Note
your observations on the worksheet.

B. Microscope Viewing

Using the microscope, observe the end face of the connector ferrule in the three
ways you learned in the Test session. Record your observations on the worksheet.
Back light the fiber to observe the core it too should be scratchless.

Typical 3 micron Cracked and

finish chipped
finish

Typical 1 micron
finish
Plucked finish

Typical 0.3 micron Cracked and

finish plucked finish.

Photos courtesy of Beuhler.

C. Loss Testing

1. Single-ended Test
Using the methods for single-ended testing (described below and in the Test
session,) test each of your connectors for loss using the single ended test method.
Record the data on the worksheet.

A single-ended test uses a matching “launch” cable on the source to mate with
the cable under test. This tests only the connector of the cable being tested which is
connected to the launch cable, (plus any loss in the cable itself which is too small to
measure in our short cables we use in this exercise) which will allow the student to test
the connector they just made in the lab.

1. Set test reference value

836700932.doc, 1/22/25, 36
1. Using the “Alco Pads”, clean the ends of all the connector ferrules and replace the
dust caps.
2. Attach one of the ST-ST cables to the source’s 850 nm LED. This will be the launch
cable
3. Turn the source and meter on
4. Use the power meter to measure the power out of the launch cable.
5. Use the trimtool (blue plastic screwdriver) to adjust the source power to a even
number like -30.0 dBm and record it here and on the worksheet _____dBm (1) or
use the meter function to set the power level to “0 dB.” This is your “0 dB” reference
power for loss measurements.
6. Disconnect the launch cable from the power meter.

2. Measure single ended loss

1. Attach a ST-ST splice bushing to the end of the launch cable.

2. Attach one end (A) of the cable to be tested to the launch cable.
3. Attach the other end (B) of the cable under test to the power meter.
4. Measure the output of the second cable and record it on the worksheet _____dBm
(2)
5. Calculate the loss: ___dBm (2) - _____dBm (1) = ____loss in dB, end A

VIII. Terminating Buffered Fiber

Terminate a piece of plain buffered fiber from a distribution cable (perhaps from a
cable that you prepared in the Fiber Optic Cables section.) This requires a different
strain relief boot than 3 mm jacketed cable and will not be crimped.

Follow Cable Preparation steps I.1, I.2, I.3 and all the steps from section II. Fiber
Preparation through section VII. Testing the Patchcord.

836700932.doc, 1/22/25, 37
 Fiber Optic Cable Termination

Name:________________________________

What are the most common methods of fiber optic connector termination used in the
field? 1._____________________ 2.________________ 3. ________________
4.____________________

What are the worst enemies of terminations ?

______________________________________________________________

How do you know when you have injected epoxy into the connector properly?
___________________________________________________________

What do we call the polishing motion we use on the lapping films?

____________________________________________________________

VIII. Testing
Once you have terminated your cable, test it and record the data on this worksheet.
Make extra copies for each patchcord if you need them.

Cable No.___________

A. Continuity Test
1. Were you able to see light through your cable?___________________________
_____________________________________________________________
2. Was there any difference in intensity when direction was reversed?
___________________________________________________________
_____________________________________________________________

836700932.doc, 1/22/25, 38
B. Microscope Inspection
Inspect each connector you install and record your observations in the table below.

Connector No. 1 2

Polish G=good, F=fair, B=bad

Scratches Y=yes, N=no

Cracks Y=yes, N=no

Chipping Y=yes, N=no

C. Loss Test, Single-ended

single ended.
Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB

Cable tested one way

Cable reversed

836700932.doc, 1/22/25, 39
 Splicing

What Students Learn:

How a mechanical and/or fusion splicing works
How to prepare fibers for splicing
Making mechanical and/or fusion splices
How to optimize the mechanical splice

Exercises:
I. Preparing the Cable
II. Stripping and Cleaving
III. Inspection
IV. Inserting the Fiber into the Splice
A. Finishing the Splice
B. Testing the Splice
C. Optimizing the Splice

Visual Aids
The following visual aids show the processes described in these exercises. They
may be shown to the students before the lab or just used as a reference by the
instructor.
FOA PPT: Splicing, Slides # 107-124
FOA Instructional Videos (Online or DVD): Mechanical Splicing
FOA Online Reference Guide To Fiber Optics: Basics/Cables, Splicing VHO
(mechanical, fusion and ribbon)

Safety:
All students and instructors must wear safety glasses in this lab.
Follow all safety rules for working with fiber.
Safely dispose of all fiber scraps and cables after use.

Materials Needed:
Safety Glasses
ST patch cord
Fiber Optic stripper
Microscope with bare fiber stage
Test equipment: VFL and OLTS
Scribe
Miller Jacket stripper
Trash bin
Mechanical Splice consumables: 3 Ultra-splices:
Alcopads or lint-free pads and 99% isopropyl alcohol
Power meter and Source
Bare fiber holder
Cleave fixture
Aramid Yarn scissors

836700932.doc, 1/22/25, 40
Mechanical Splicing

Generally splices are used to connect two fibers permanently. There are two
basic categories of splices: Mechanical and Fusion.
Fusion splicing is the preferred method for splicing long distance singlemode
cable plants, as it’s low loss and reflectance maximizes cable plant performance.
Multimode fiber is more often spliced by mechanical splices, as the higher loss is
acceptable, reflectance is not a problem, and fusion splicing sometimes has strange
effects on bandwidth when it melts the numerous layers in the core of the multimode
fiber.

Mechanical Splices
Mechanical splices use some alignment mechanism to align two fibers with index
matching fluid between to fiber ends. Then some type of clamp grabs the fibers and/or
buffers to hold the fibers in place.
There are many styles of mechanical splices. However, they all share some
common characteristics. All mechanical splices use an index matching gel or oil to
reduce loss and reflections. They are simple to install, requiring only a few basic tools.
Typical mechanical splice losses are 0.5dB or less.
While mechanical splices require little in terms of specialized tools or fixtures, the
splices themselves may be expensive, due to the critical nature of aligning the fiber
ends to sub-micron precision. If you only have a small number of splices to install,
mechanical splices may still be less expensive than fusion splicing.

Splice Installation
Specific installation instructions will vary slightly between manufacturers for their
different styles of mechanical and fusion splices. However, every splice, fusion and
mechanical, follows this same basic procedure:
1. Preparing the cable ends
2. Stripping and cleaving the fiber
3. Aligning and optimizing the splice
4. Fixing the splice to hold the fiber permanently
5. Testing the splice for loss

The Ultrasplice

Drawing courtesy of ACA

836700932.doc, 1/22/25, 41
I. Preparing the Cable

Wear Safety Glasses for this exercise!!

Note: If cutting a patchcord and splicing it, record the loss reading of the cable before
beginning.

1. Cut the cable in half.

2. Remove approximately 6 inches of the jacket from each end leaving the buffered
fiber. (See the cable or termination exercise for procedures)

II. Stripping and Cleaving

Wear Safety Glasses for this exercise!!

Do not strip both fibers to be spliced at once. Strip one side, cleave it, insert it into the
splice, then strip the other fiber. This is safer and avoids breakage.

1. With the fiber stripper, strip away the buffer coating exposing approximately 1-1/2 to
2 inches of the glass fiber.
2. Lay the fiber on the cleave fixture with the buffer end 7 mm (0.3 in.) from the center
(pivot point) of the fixture, holding it tightly with two fingers as shown in the cleaving
instructions in the Toolbox Manual.
3. Scribe the fiber with the scribing tool at a point 7-9 mm from the end of the buffer.
4. Push down both ends of the fixture until it touches the tabletop.
5. The fiber should cleave at the scribe point. (This process takes some practice to get
the right “feel” for the scribe. You may want to practice with other fiber supplied in
the Termination consumables kit before trying it on your patchcord.)

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III. Inspection

Inspect your cleave using the bare fiber fixture for the microscope.

Note: A bare fiber fixture for a regular microscope can be made from a flat piece of
metal, plastic or thin cardboard. Tape or hold the fiber on the fixture to view.

A low loss splice depends on a well made cleave (see termination section for
details). Using the microscope and bare fiber stage view the cleave. It should be a
clean square cut (figure a). Excessive losses will be caused by an angle cleave (figure
b), a cleave with overhanging material (figure c) or a cleave with missing material (figure
d). Re-strip, scribe and cleave again if the cleave is not adequate.

When cleaving always wear protective eye wear.

Correct Cleave Incorrect

Cleaves
b
a
c

IV. Inserting the Fiber into the Splice

Insert the cleaved fiber into one end of the splice. The cleave length should be 7-
9 millimeters. The knurled section of the locking nut represents the exact cleave length.

7 - 9 millimeters
Cleave length

1. If using fiber with a buffer size larger than 500micron, it is necessary to remove the
Blue Tube and open locking nut one half turn. Remove the blue tube.
2. Carefully insert the fiber into the spice, do not force it.
3. The fiber should be visible in the capillary tube.
4. Center the fiber in the capillary tube.
5. Lock the fiber in the splice by tightening the locking nut with a clockwise rotation.
(The fiber is held in place by the collet. The collet acts like a drill chuck. When the

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 locking nut is tightened down on it the collet grips the buffer of the fiber. The locking
nut is designed to strip if too much force is used.)

A. Finishing the Splice

1. Cleave the other fiber in the same manner as before.

2. Insert the second fiber and gently butt up against the first fiber. Do not force the
fibers together, this will cause them to break.
3. Secure in place with the locking nut.

B. Testing the splice

1. Use the meter, source and one of the preterminated cables to test the cable which
now has a splice in it.
2. Record the loss.
3. Calculate the additional loss of the splice.

C. Optimizing the Splice

You can sometimes improve the loss of a mechanical splice by gently

withdrawing one of the fibers a slight amount, rotating it slightly and reinserting it. Try
this with your splice.

1. Attach the spliced cable to the meter and source

2. Record meter reading
3. Unlock one splice locking nut
4. Pull that fiber out by 1mm (about 1/16 inch)
5. Rotate the fiber 30 degrees and gently reinsert
6. Note the power meter reading. Did the loss increase or decrease?
7. Try the process again and note the results on the worksheets.

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 Fusion Splicing Lab

What Students Learn:

How to prepare fibers for fusion splicing
The process of fusion splicing
How to protect fusion splices

Exercises:
I. Preparing the Cable
II. Stripping fibers
III. Cleaving
IV. Fusion splicing
V. Attaching splice protector

Visual Aids
The following visual aids show the processes described in these exercises. They
may be shown to the students before the lab or just used as a reference by the
instructor.
FOA PPT: Splicing, Single fiber: Slides # 37-79, Ribbon: Slides # 80-105
FOA Instructional Videos (Online or DVD): Mechanical Splicing
FOA Online Reference Guide To Fiber Optics: Basics/Cables, Splicing VHOs
(mechanical, fusion and ribbon)

Safety:
All students and instructors must wear safety glasses in this lab.
Follow all safety rules for working with fiber.
Safely dispose of all fiber scraps and cables after use.

For the trained fiber optic technician who already understands the basics of fiber
optics and installation practices, this advanced lab is designed to introduce the student
to the theory and practice of fusion splicing fiber optics. The student will learn what a
fusion splice is, what equipment is needed, how it is done and will practice making
single fiber and ribbon fiber splices, placing splices into a splice tray, including testing
each splice as made, mirroring actual field installation practices. For students in a basic
fiber course, a shorter introduction to splicing can be done by having each student strip
fibers and complete one fusion splice, then covering splice trays and closures as a
class.
Teaching fusion splicing requires training material specific to the splice machine
chosen, so if you intend to teach fusion, get the manufacturer to of the chosen machine
to assist you and provide training materials if available. The FOA PPT on Splicing and
the Online VHOs cover these processes step by step in great detail using typical
splicers.
It is assumed that the instructor teaching a fusion splicing lab will be familiar with
the equipment and its use and has available training aids like the FOA PPT on splicing
and/or Internet access and can project the VHOs. An advanced lab should have access
to several spools of fiber of lengths greater than 1 km for splicing and an OTDR to test

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the splices made in class. Students should be introduced to the OTDR before using it to
verify splices.

Lab Setup

The lab is divided into separate stations, with one station set up with an OTDR
that will be used to test the finished splices, and one or more splicing stations. For
example, a typical lab might include both single fiber and ribbon fiber splicing. The lab
session has the students split into 3 groups with one group starting at the fusion splicer,
one at each splicing station. Each group rotates to get at least one turn on each setup,
learning how to splice and test each splice.

Wear Safety Glasses for this exercise!!

Lab Sessions

Students participate in a lab consisting of three stations:

Single fiber splicing
Ribbon fiber splicing
Testing splices with an OTDR (optical time domain reflectometer) and/or VFL
(visual fault locator)
Students will be divided into 3 groups, each assigned to one station
Students will be shown the process by the instructor, then each student will participate
in the activity of the station.
Students at each station will rotate using the equipment and watching and helping the
other students
Each student will fill in a worksheet which includes:
Single fiber splicing – estimated loss from splicer and actual OTDR loss
Ribbon fiber splicing – estimated loss from splicer and actual OTDR loss for one
fiber
Testing: OTDR data or trace for one completed link (4 spools and 2 splices)
Students should rotate through each station

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Testing Fusion Splices
Every fusion splicer makes an estimate of the loss of the splice using calculations
based on the alignment method. This estimate can be inaccurate on some splices. The
lab setup shown has the advantage that each splice can be tested with an OTDR and
the loss of the splice verified. If possible, for one or more splices, test in each direction
with the OTDR and note differences. If a directional difference is noted, measure the
attenuation coefficient of each fiber and see if the relationship of fiber attenuation
coefficient and loss differences at the splice are as predicted.

Instructor Notes

This lab works best with at least two instructors, both familiar with the processes
being taught.
The lab should be started completely set up with all spools already spliced together
so students break splices and redo.
The OTDR should already show a trace of the setup. This will get class started
faster.
Start the lab by showing the OTDR students (or everyone if the OTDR trace can be
projected) how to make a test with the OTDR and have them get a valid trace. Then
while the other students are set up for splicing, the OTDR students can analyze the
trace.
Next show the single fiber splice students how to splice and get them started by
breaking the splice already made and having them each redo it.
Finally instruct the ribbon splice students and have them start redoing the ribbon
splice.
Once everyone is started, the instructor should move between groups to help the
students. After a short while, students should help each other.
Option: If the class is small, the instructor can go to each station and do one splice
or test while the students watch over his shoulder.
Alternatively, a video of the activities can be used to familiarize the students with the
processes.

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 Splicing
Name:________________________________

1. On the following table, answer the questions by choosing the correct splice for each
statement.

Fusion Splice Mechanical Splice

Lowest Loss

Best back reflection

Best for singlemode

Best for multimode

Least equipment cost

Least inexpensive for high

volumes of splices
Least inexpensive for low
volumes of splices

2. What is the typical loss dB dB

for each type splice?

Mechanical Splicing
3. What loss did you get when you tested your splices?

#1_________________________________________dB

#2_________________________________________dB

#3_________________________________________dB

Fusion Splicing
4. What loss did you get when you tested your splices?

#1_________________________________________dB

#2_________________________________________dB

#3_________________________________________dB

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 Fiber Optic Testing

Students Will Learn

Basics of fiber optic test procedures
Variables in testing methods
Accuracy of testing

Exercises:

I. Continuity
II. Visual Inspection And Fault Location
III. Measuring Optical Power
A. Power or Loss? (“Absolute” vs. “Relative”)
B. Optical Power Range
C. Wavelength Calibration
IV. Measuring with a Power meter
A. Measuring Power
B. Wavelength calibration differences
V. Loss Testing
A. The Power Budget
B. Single Ended Loss Test
C. Double Ended Loss Test
D. Effects of mode power distribution

VI. OTDR Testing

Visual Aids
The following visual aids show the processes described in these exercises. They
may be shown to the students before the lab or just used as a reference by the
instructor.
Presentation Slides: Testing PPT: Choose for topic covered (slides 99-110
compares the 5 ways to test cables which is important)
FOA Instructional Videos (Online or DVD): Testing (shows insertion loss only)
FOA Online Reference Guide To Fiber Optics: Basics/Testing, Testing (as
appropriate)
OTDR Course, OTDR Simulator

Safety:
All students and instructors must wear safety glasses in this lab.
Follow all safety rules for working with fiber.
Safely dispose of all fiber scraps and cables after use.

Equipment Required
Visual fiber tracer and/or Visual Fault Locator (VFL)
Connector Inspection microscope
Light source and power meter (OLTS)

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Appropriate connector adapters (ST or SC) for the power meter
2 reference test cables (launch and receive)
Testing Consumables:
Cables to test (terminated cables of various lengths which can be interconnected to
create longer cables for testing)
2 ST-ST or SC-SC mating adapters
Alcohol pads or lint-free wipes and 99% isopropyl alcohol for cleaning connectors

Fiber Optic Testing

In the hands-on testing, each student should have exercises in all four test
methods: microscope inspection of a connector ferrule, visual tracing and fault location,
optical power measurement, insertion loss testing and OTDR testing. Labs should have
available a variety of cables some of which are good and some bad for use in student
exercises. One way to have lots of cables to test is to save student termination
exercises for the student to test in this lab and for other students to test also.
If time permits and equipment is available, using an OTDR to find faults and
measure splice loss (bi-directional and average) is recommended. OTDRs are used for
testing and troubleshooting some fiber optic networks, but these instruments are often
considered too specialized to include in a basic course on fiber optics. However, since
some OTDR companies are trying to convince users to require OTDR testing for every
cable, whether or nor OTDR testing is relevant, we highly recommend including an
OTDR lab. The Curriculum Starter Kit includes an OTDR simulator that runs on
Windows XP and can be projected for class use that instructors have told us is better for
teaching than a real OTDR. Students may be given a copy of the OTDR simulator to
install on their computers to analyze traces for homework.

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I. Visual continuity testing and fault location

What Students Learn:

What is the difference between a visual tracer and visual fault locator
How to operate both tools

In the field, you can use the visible fiber tracer to test all your cables for continuity
and find any with broken fibers or connectors. It also allows tracing fibers to ensure
transmitters are properly connected to receivers.

1. Attach one of the two terminated cable

assemblies supplied to the visible fiber
tracer “flashlight”. Look at the other end
of the cable and notice the light
transmitted through the core of the fiber.
2. Repeat the test with other cables
supplied.
3. Record your observations on the
worksheet.

Notice how you can use the Visible fiber

tracer to trace the path of the fiber
throughout networks, as its range can be
up to two miles (3 km) or more.
Visible laser sources with higher power called visual fault locators or VFLs can
be used to trace singlemode fiber for longer distances and find breaks or stress loss in
shorter fibers.

1. Using a SM fiber cable with a yellow jacket, attach the cable to a VFL.
2. Using your fingers, put a bend in the cable and see the light shining through the
jacket. Don’t bend too tightly; although fiber optic cable is strong, it will break under
abuse.

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II. Visual inspection with a microscope

What Students Learn:

How to operate a fiber optic microscope
How to identify various faults of connectors

Using the microscope and one of the test cables, inspect the connector polished
end three ways and note the differences.

1. Direct inspection, where the connector is aimed straight toward the microscope lens.
How well does the fiber fit in the hole in the connector ferrule? Is it centered? Sketch
what you see on the worksheet.

2. Direct inspection with light in the core of the fiber, by

attaching the other end of the cable to the Visible fiber
tracer. Note the light transmitted through the core now QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

allows you to determine where the core and cladding on

the fiber are. Sketch your observations on the
worksheet.

3. Angular or oblique inspection. Following the microscope Direct Inspection

instructions, set the connector stage at an angle or use
oblique lighting. Note the fine finish on the fiber end.
Can you find the core this way? What do you see best?
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

4. Remove the connector from the microscope and touch it

to your fingertip. Inspect it again. Touch the connector to
a dirty surface and inspect it again.
Angular/Oblique
Inspection

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III. Optical Power

What Students Learn:

What is the difference between absolute and relative optical power?
What is the difference between “dB” and “dBm”?
Why are power meters calibrated at certain wavelengths?

A. Power or Loss ? (“Absolute” vs. “Relative” power)

Practically every measurement in fiber optics refers to optical power. The power
output of a transmitter or the input to receiver are “absolute” optical power
measurements, that is, you measure the actual value of the power. Loss is a “relative”
power measurement, the difference between the power into a component like a cable or
a connector and the power that is transmitted through it. This difference is what we call
optical loss and defines the performance of a cable, connector, splice, etc.

B. Optical Power Range

Relative Optical Power Measurements

Because optical power measurements cover such a wide range, up to
1,000,000:1, the power is expressed in a compressed logarithmic scale, called decibels
or dB. For every 10 dB change in optical power, there is a 10 times change in power. If
the dB value is “+”, the power has increased and if the dB is “-”, the power has
decreased. However, to confuse the issue, “loss” is read from the meter as a “-dB” but
generally expressed as a positive term!
See the table below for some ratios of power to dB measurements.

dB loss % change dB change Multiplier

in power
0 0 10 10
0.1 2.3 20 100
0.2 4.5 30 1,000
0.5 10.9 40 10,000
1.0 20.6 50 100,000
2.0 36.9 60 1,000,000
3.0 50.1
5.0 68.4
10.0 90

Absolute Power Measurements

The optical power meter usually measures absolute power in “dBm”, or dB
referenced to one milliwatt of power. dBm is absolute power, a measure of power
referred to a standard value of 1 milliwatt (one one-thousandth of a watt.)

See also the graph on the following page.

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 dBm watts dBm watts
+10 10 mW -10 100 W
(milliwatts)
+3 2 mW -20 10 W
0 1 mW -30 1 W
-3 500 W -40 100 nW
(microwatts) (nanowatts)
-6 250 W -50 10 nW

C. Wavelength Calibration

Power meters, generally, are calibrated at 850, 1300, and 1550nm to

compensate for the wavelength variation of the sensitivity of the detector used. There
are applications were 665nm and 790nm wavelengths are used, for example 665nm is
often used with plastic optical fiber. Multimode networks use the 850nm and 1300nm
wavelengths and singlemode networks use 1300nm and 1550nm wavelengths.
When testing, it is important to make sure that the wavelength selected on the
meter matches that of the source.

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Measuring with a Power Meter

What Students Learn:

What is the difference between absolute and relative optical power
What is the difference between “dB” and “dBm”
How to operate a fiber optic power meter

A. Measuring Power – Absolute Power

You need a power meter, source and reference cable or any patchcord. Connect
a cable and connect it between the source’s 850 nm LED output and the meter. Turn on
the source with the switch toward the 850 nm LED. Turn on the meter and set the meter
calibration switch to 850 nm and the range to “dBm.” Read the meter and note it on the
worksheet below.

Meter reading @850 nm: _____________ dBm

If the source output power is adjustable, decrease the power output of the
source. You may also use an attenuator or induce attenuation in the cable by wrapping
it around a 13 mm (1/2”) mandrel. Note as the power decreases, the number on the
meter display becomes a “larger” negative number, e.g. it will go from -10 dBm down to
-12, -15, -20, -30, etc. Increasing the power (turning the pot counterclockwise) will
cause the numbers on the meter display to get “less negative”. This is a consequence of
the logarithmic display of power.
If you can get power levels over 1 mW (possible with many laser sources), you
will find the numbers will go to “0” at exactly 1 mW, then become positive (+) and
become larger as the power is increased. This is caused by the fact that the scale of
dBm is all relative to 1 mW and the reading is “+” for power levels greater than 1 mW
and “-” for levels below 1 mW.
When you measure loss, expect the meter to read a “larger” negative number.
The difference between the reference power and the test power will be the loss, but the
value for loss will generally be expressed as a positive number, like 3 dB loss.

Meter reading @850 nm with lower power level: _____________ dBm

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B. Relative Power
Repeat the exercise using the meter’s “dB” scale. Set up with the source and use
the meter’s “ Zero dB” function to make the meter read “ 0.0 dB.” Reduce the source
power (on the source or by attenuation) and note the reading on the meter. Is the
reading “+” or “-“ when the power decreases?

Meter reading @850 nm with lower power level: ______0______ dB

Meter reading @850 nm with lower power level: _____________ dB

B. Wavelength Calibration
Using the same setup as above, with the meter set on the “dBm” scale, measure
the optical power from the cable attached to the source at the wavelength of the source,
e.g. 850 nm. Change the meter to a calibration of 1300 nm and 1550 nm (as available)
and record the difference. What does this tell you about the detector sensitivity?

Meter reading @ 850 nm _______ dBm

1300 nm _______ dBm
1550 nm _______ dBm

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IV. Loss Testing

A. The Loss Budget (What loss value should you expect?)

What Students Learn:

What is a Loss Budget and a Power Budget
How to set the reference for loss testing
Differences in measurements by direction and modal distribution

With a given network, it is designed to work on a cable plant with a loss less than
the transmitter and receiver can tolerate. This loss is generally calculated at the design
phase and is used as a pass/fail criteria after installation when testing.
The loss you measure should be close to what you predict when you do a power
budget. The loss is the sum of the loss in the fibers over the length installed, plus the
loss of all connectors and splices in the installed cable plant. Below are some tables to
help calculate the loss budget.

Cable Plant Passive Component Loss Budget

Step 1. Fiber loss at the operating wavelength

Cable Length (km)
Fiber Type Multimode Singlemode
Wavelength (nm) 850 1300 1300 1550
Fiber Atten. (dB/km) 3 1 0.5 0.4
Total Fiber Loss

Step 2. Connector Loss

Typical Connector Loss 0.5 dB
Total # of Connectors
Total Connector Loss

Step 3. Splice Loss

Mech. Fusion
Typical Splice Loss 0.5 dB 0.2 dB
Total # splices
Total Splice Loss

Step 4. Total Cable Plant Attenuation

Total Fiber Loss (dB)
Total Connector Loss (dB)
Total Splice Loss (dB)
Other (dB)
Total Link Loss (dB)

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Using these guidelines and the worksheets at the end of this section, calculate the loss
budget for the following two cable plants:

1) Multimode campus LAN backbone, 1.7 km long, four connector pairs (plus the end
connectors) and no splices. Calculate loss at both 850 and 1300 nm.

2) Singlemode network, 17 km long, 6 fusion splices. Calculate loss at both 1300 and
1550nm.

(Hint: don’t forget the connectors on each end! )

Power Budget

Fiber Optic networks are designed to operate within certain power levels. If the
loss is too high the signal power at the receiver will be too low for proper operation. If
the signal power is too strong at the receiver the receiver will saturate. This is why you
test with a power meter, to ensure the received power is in the correct range.
With the following parameters, how much loss can the network tolerate?

Transmitter Power: -10 dBm

Receiver Power (minimum): - 22 dBm
Loss Budget: _______ dB

Would such a network work on either of the cable plants above?

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B. Single Ended Loss Test (FOTP-171)

What Students Learn:

What is a single-ended cable plant loss test and where is it used
How to set the reference for loss testing
Differences in measurements by direction and modal distribution

Use the single ended test method to test your launch and receive jumpers that
you will use to test the cables you will terminate later.
A single-ended test uses a matching “launch” cable on the source to mate with
the cable under test. This tests only the connector of the cable being tested which is
connected to the launch cable, plus any loss in the cable itself (which is too small to
measure in our short cables we use in this exercise.)

1. Set test reference value

7. Using the “Alco Pads”, clean the ends of all the connector ferrules and replace the
dust caps.
8. Attach one of the ST-ST cables to the source’s 850 nm LED. This will be the launch
cable
9. Turn the source and meter on
10. Use the power meter to measure the power out of the launch cable.
11. Use the trimtool (blue plastic screwdriver) to adjust the source power to a even
number like -30.0 dBm and record it here and on the worksheet _____dBm (1) or
use the meter function to set the power level to “0 dB.” This is your “0 dB” reference
power for loss measurements.
12. Disconnect the launch cable from the power meter.

2. Measure single ended loss

6. Attach a ST-ST splice bushing to the end of the launch cable.

7. Attach one end (A) of the cable to be tested to the launch cable.
8. Attach the other end (B) of the cable under test to the power meter.
9. Measure the output of the second cable and record it on the worksheet _____dBm
(2)
10. Calculate the loss: ___dBm (2) - _____dBm (1) = ____loss in dB, end A

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3. Measure opposite direction

Reverse the cable being tested and test the other direction
Measure the output of the cable under test_____dBm (3)
Calculate the loss: ___dBm (3) - _____dBm (1) = ____dB loss, end B
Is there a difference in the two measurements ? How much ____dB ? Why ?

Repeat the procedure above with the cables reversed, that is, the launch cable
becomes the cable being tested and the cable just tested becomes the launch cable.
Record the data on the worksheet.

5. Determine the effects of mode power distribution

Repeat the single ended test, testing the cable in the same direction, but change the
modal power distribution in the launch cable using a mandrel wrap.

Measure a cable using the method above and record the loss: ______ dB
Set that cable aside so you know which end was tested.
Measure the output of the launch cable as when setting a “0 dB” reference.
Wrap the launch cable five times around a ~13 mm (0.5”) mandrel.
Measure the output of the launch cable again. What happened?
Use the output of the launch cable with the mandrel wrap as your “0 dB” reference and
repeat the tests of the cable, comparing the difference in losses measured. What was
the result? ______ dB. Why?

Refer to the FOA Online Reference Guide, Testing & Troubleshooting Section, pages
Fiber Loss Testing and Multimode Modal Control and Modal Distribution Effects on
Multimode Fiber and Cables Measurements for explanations of modal effects.

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C. Double Ended Cable Plant Loss test (OFSTP-14)

What Students Learn:

What is a double-ended cable plant loss test and where is it used
How to set the reference for loss testing
Differences in measurements by direction and modal distribution

Installed fiber optic cable plants are generally tested in a double-ended test
covered by TIA OFSTP-14 for multimode fiber and )FSTP-7 for singlemode fiber which
tests both end connectors and all the fiber optic cables and other components in
between.

1. Measure double ended cable loss

Measure the output of the launch cable or use the meter function to set the power level
to “0 dB.” This is your “0 dB” reference power for loss measurements.
Attach a ST-ST splice bushing to the end of the launch cable.
Attach one end (A) of the cable to be tested to the launch cable.
Attach a ST-ST splice bushing to the other end (B) of the cable being tested.
Attach a second cable to the end of the cable being tested to become the receive cable.
Attach the other end of the receive cable to the power meter.
Measure the output of the cable and record it on the worksheet _____dBm (2)
Calculate the loss: ___dBm (2) - _____dBm (1) = ____loss in dB, end A and B.

2. Measure the other direction

Reverse the cable being tested and test the other direction
Measure the output of the meter _____dBm (3)
Calculate the loss: ___dBm (3) - _____dBm (1) = ____dB loss, end B
Is there a difference in the two measurements ? How much ____dB ? Why ?

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3. Effects of reference methods
Industry standards offer three methods for setting a “0 dB” reference for testing installed
fiber optic cable plants, using one, two or three reference cables. (See FOA Online
Reference Guide, Testing, Technical Issues: Five Different Ways.)
Repeat the test above with the “0 dB” reference set using 1, 2 and 3 reference cables
corresponding to OSTP-14 Method B, A and C respectively. Not the results below.
Explain the differences. (See FOA Online Reference Guide, Testing, Technical Issues:
The Math of Insertion Loss Testing.)

Loss with Method A ( 2 cable reference) _______ dB

Loss with Method B ( 1 cable reference) _______ dB
Loss with Method C ( 3 cable reference) _______ dB

What causes the difference? ____________________________________________

Why use different methods? ____________________________________________

4. Determine the effects of mode power distribution

Measure the cable loss for the cable under test, then use a mandrel wrap on the launch
cable as in the single-ended test, reset the “0 dB” reference and test again. What was
the result? Why?

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D. OTDR Testing

What Students Learn:

The appropriate applications of an OTDR
The correct way to set up the OTDR
How to analyze traces on the OTDR
OTDR problems and limitations

OTDRs test optical fibers and fiber optic cable systems using an indirect method
that depends on the backscatter of light in the fiber. While all international standards
require OLTS (light source and power meter) testing of installed cable plants, OTDRs
are routinely used to check splices and find sources of stress loss that can affect long
term reliability. OTDRs are also used for fault location and troubleshooting.
While OTDRs are primarily used for outside plant cabling, manufacturers have
been promoting their use in premises and campus networks. The technical calls taken
by the FOA indicates that the use of OTDRs in these types of short cable plants has
been a major source of confusion, particularly for installers who are new to OTDRs and
have been told to connect it to the network and hit the “autotest” button.
Thus, the goal of the classroom training and this lab is to show the students the
proper applications in which to use of the instrument as well as how to use it properly.
This may be done in two ways, using the OTDR Simulator available from the FOA or an
OTDR and simulated cable plant. We will offer both ways.

1. Using The OTDR Simulator

The FOA Testing and OTDR PPTs have details on how the OTDR works. The
instructions for the OTDR simulator are in a manual and on a PPT presentation. The
simulator can be loaded on a Windows XP PC using the installation instructions. There
are three file folders containing about 80 traces that should be loaded on the PC also.
One contains multiple traces of the same cable plant taken with different OTDR setups,
one contains field traces and one has FTTX traces through a PON-type coupler (with
only 2 ports to simplify understanding how couplers are seen on OTDRs.)
The instructor needs to practice with the OTDR simulator to understand its use.
The PPT on how to use the simulator is good training.

Setting up the OTDR

The secret to getting good traces in the OTDR is to set the test parameters
properly. In the “Parameters” folder, there are 26 traces taken of one cable plant –
about 5.2 km of multimode fiber in 4 segments - with each trace using a different setup
parameter. Thus, one can open traces from the folder that can be shown as
comparisons on the display to allow the student to see the effects of the setup.

Range
There are 6 range files. Range changes the scale on the display and the timing
of the test pulses. Note that on the longer ranges, the 5.2 km cable plant has poor
resolution and on the shortest one, the display is distorted since the OTDR does not
have time to get the test pulse back before the next pulse is sent.

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Averaging
The OTDR sends out multiple test pulses and averages the result. Take a look at
the traces at 1 and 1024 averages and note the difference in signal to noise in the trace.
Try several others to see what is a good value for this cable plant.
0
Index of Refraction (n)
The Index of Refraction (n) is a measure of the speed of light in the fiber, so it is
used to calibrate the distance to events. Compare the three traces taken at different
values of n and see how the traces change.

Pulse Width
Wider pulse widths give the test pulse more energy so the OTDR can see a
longer distance. But the trade off is resolution, not just in distance but in dB, as the
comparison between these traces show.

Wavelength
OTDRs typically test at two wavelengths, 850 and 1300 nm for multimode, 1310
and 1550 for singlemode and sometimes 1620 nm for finding high stress loss areas in
singlemode cable plants. Open the 850 and 1300 nm traces and compare them.

Analyzing Fiber Traces

There are 50 traces to analyze, including 4 through couplers for seeing what
happens in a PON system. Some of these are analyzed in the notes to the OTDR
simulator but all are available for classroom or student analysis. See if you can find the
one with the “perfect” gainer.

2. Using An OTDR In The Classroom

If the classroom has an OTDR for student training, it needs appropriate launch
cables, sometimes called “pulse suppressor” cables and several long spools of fiber to
allow the students to see how the OTDR analyzes fibers. These long spools can be
joined by fusion splicing them together or by terminating them. Multimode can be
terminated directly (using a breakout kit is the fibers are 250 micron buffered fibers) but
singlemode fibers should have pigtails spliced onto the fibers.
OTDRs are sometimes used to test bare fibers using mechanical splices to
connect to the fiber to be tested. The splices used in the mechanical splicing exercise
can be used to splice a long pigtail (long enough to be a good launch cable) to a spool
of fiber to test.
Exercises should include setting up the OTDR parameters and then analyzing
traces. Additional exercises include using short fibers to show the limitations of the
OTDR when testing short cables and, if the short cable is prepared with a cleaved or
polished far end, to show ghosts and showing how the OTDR autotest function
compares to a properly set up OTDR.
If possible, use an OTDR that has provision to be connected to a projector to allow all
students to participate in the activities.

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 Fiber Optic Testing Worksheet

Name:________________________________

I. Continuity
1. What does the visual tracer test?____________________________

2. How far will it reach?________________________

3. What problem will it solve when connecting up all the different fibers and equipment
in a network?

II. Microscope Inspection

Which way do you want to look at the fiber to see:

Fiber centering in the ferrule hole_______________________________

Polishing finish _____________________________________________

Cracks ___________________________________________________

II. Microscope Inspection:

Sketch what you see

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III. Measuring Optical Power:
1. Which optical measurment is absolute and which is relative?

Power ___Relative ___Absolute

Loss ___Relative ___Absolute

2. Which is the higher power?

0dBm or -30dBm ?
0dBm or +10dBm ?

3. Convert to 0dBm to Watts.

0dBm = ________

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IV. Power Budget
Cable Plant Passive Component Loss Budget Worksheet

Using these guidelines, calculate the loss budget for the following cable plant.

Design: Singlemode network, 17 km long, 6 fusion splices. Calculate loss for both 1300
and 1550nm.

Step 1. Fiber loss at the operating wavelength

Cable Length (km)
Fiber Type Multimode Singlemode
Wavelength (nm) 850 1300 1300 1550
Fiber Atten. (dB/km) 3 1 0.5 0.4
Total Fiber Loss

Step 2. Connector Loss

Typical Connector Loss 0.5 dB
Total # of Connectors
Total Connector Loss

Step 3. Splice Loss

Mech. Fusion
Typical Splice Loss 0.5 dB 0.2 dB
Total # splices
Total Splice Loss

Step 4. Total Cable Plant Attenuation

1300nm 1550nm
Total Fiber Loss (dB)
Total Connector Loss (dB)
Total Splice Loss (dB)
Other (dB)
Total Link Loss (dB)

(Hint: don’t forget the connectors on each end!)

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 Hands-On Worksheet

Fiber Optic Testing

IV. Power Budget
Cable Plant Passive Component Loss Budget Worksheet

Using these guidelines, calculate the loss budget for the following cable plant.

Design: Multimode campus LAN backbone, 1.7 km long, four connector pairs (plus the
end connectors) and no splices. Calculate loss at both 850 and 1300 nm.

Step 1. Fiber loss at the operating wavelength

Cable Length (km)
Fiber Type Multimode Singlemode
Wavelength (nm) 850 1300 1300 1550
Fiber Atten. (dB/km) 3 1 0.5 0.4
Total Fiber Loss

Step 2. Connector Loss

Typical Connector Loss 0.5 dB
Total # of Connectors
Total Connector Loss

Step 3. Splice Loss

Mech. Fusion
Typical Splice Loss 0.5 dB 0.2 dB
Total # splices
Total Splice Loss

Step 4. Total Cable Plant Attenuation

850nm 1300nm
Total Fiber Loss (dB)
Total Connector Loss (dB)
Total Splice Loss (dB)
Other (dB)
Total Link Loss (dB)

(Hint: don’t forget the connectors on each end!)

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IV. Loss Testing

B. Single-Ended Loss Testing

Test 1. One direction

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested one way

Cable reversed

Test 2. Reverse Direction

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested one way

Cable reversed

Test 3. Mandrel wrap

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested one way

Cable reversed

1. Why is this called a “single-ended” test? __________________________.

__________________________________________________________________
2. Were the results the same when the cable was reversed? Why? _______________
__________________________________________________________________
3. Were the results the same when the mandrew wrap on the launch cable was used?
Why? ____________________________________________________________
__________________________________________________________________

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B. Double-Ended Loss Testing

Test 1. One direction

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested one way

Cable reversed

Test 2. Reverse Direction

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested one way

Cable reversed

Test 3. Effects of reference methods

Loss with Method A ( 2 cable reference) _______ dB
Loss with Method B ( 1 cable reference) _______ dB
Loss with Method C ( 3 cable reference) _______ dB

Test 3. Mandrel wrap

Reference power level ______ dBm (1)

meter reading dBm (2) loss in dB
Cable tested with plain
launch cable
Cable tested with mandrel
wrap on launch cable

1. Why is this called a “double-ended” test? ________________________________

__________________________________________________________________
2. Were the results the same when the cable was reversed? Why? ______________
__________________________________________________________________

3. What is the difference in the loss measured with the three different reference
methods? _________________________________________________________
__________________________________________________________________

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