optic connectors from the 1970s , 1980s, 1990s, 2000s (bottom
- 1. Introduction
One often sees articles written about fiber optic
networks that implies that fiber optics is "new." That is
case. The first fiber optic link was installed in Chicago in
1980, commercial long distance links were in use and fiber
links for RS-232 were available. Since that beginning, fiber
very commonplace - one should say dominant - in the
you make a long distance call today, you are undoubtedly
fiber optics, since it has replaced over 90% of all the
for long distance communications. Most large office
fiber in the building itself. Only the last link to the
and phone are not fiber and installations of fiber to the
CATV also has discovered fiber optics, along with compressed
video. Most large city CATV systems have been converted to
backbones which allow voice and data transmission in
addition to video.
The LAN backbone also has become predominately fiber-based.
back-end of mainframes and storage area networks (SANs) are
totally fiber. Only the desktop is a holdout, currently a
between the copper and fiber contingents.
Fiber optics offers an unrivaled level of security. It
cannot be easily
jammed or tapped and is immune to interference. It is widely
security cameras, perimeter alarms and other critical
military, government, utility and civilian applications.
Fiber optics really is the medium of choice for long
bandwidth or secure communications. Lets look at why it is,
evaluate the economics of copper versus fiber and how to
networks with the best availability of options for
Its really all a matter of economics
Fiber optics has become widely used in telecommunications
its enormous bandwidth and distance advantages over copper
Commercial systems today carry more phone conversations over
a pair of
fibers than could be carried over thousands of copper pairs
and can be
run hundreds of kilometers between all-optical repeaters.
costs, installation and splicing labor and reliability are
fiber's favor, not to mention space considerations.
In CATV, fiber pays for itself in enhanced reliability and
to offer enhanced services. The enormous number of repeaters
used in a
broadcast cable network are a big source of failure. CATV
and branch architecture means and upstream failure causes
all downstream users. Reliability is a big issue, since
viewers are a
vocal lot if programming is interrupted! The ability to
access has created significant revenue streams for CATV
For LAN and other datacom applications, the economics are
today. For low bit rate applications over short distances,
is often a better choice. As distances go over 50 to 100
speeds above 1 Gb/s, fiber begins to look more attractive.
does fiber have more bandwidth capability, but very high
links use 4-8 times more power than fiber and have latency
Upgradeability usually tilts the decision to fiber, as one
fiber has already outlived a half-dozen generations of
Installing laser-optimized fiber today will provide a long
to any cable plant.
applications demand fiber. Factory floors are messy
environments where optical fiber, both glass and plastic,
everywhere to provide reliable communications. Long CCTV
security systems are now almost exclusively fiber. Even
cars use fiber (POF) for safety and
systems. If reliable communications are a must, fiber is
Technology often says go fiber
Fiber's advantages over copper result from the physics of
with photons instead of electrons. In glass, optical
much less than the attenuation of electrical signals in
copper and much
less dependent on signal frequency. We all know that fiber
transmission neither radiates RFI nor is susceptible to
making it the only choice for secure communications. Unlike
wires that radiate signals capable of interfering with other
equipment, fiber is totally benign. Utility companies even
lines with fibers imbedded in the wires for both
The bandwidth/distance issue is what usually convinces the
switch to fiber. Although with today's applications,
multimode fiber is
used at 100-1000 Mb/s for datacom applications and is usable
up to 10
Gb/s. Singlemode fiber offers virtually unlimited bandwidth,
with DWDM (dense wavelength division multiplexing.)
more on fiber
copper generally and in LANs.
Here are some advanced ways to learn more about fiber
FOA's free online training program
Guide To Fiber Optics
or Copper? A general
overview and a specific
look at fiber in LANs.
Asked Questions (FAQs)
FOA Tech Topics
- 2. Understanding Fiber
Fiber optic links are the communications pathways between
link is bidirectional, usually with signals transmitted in
directions on two different fibers. Using two fibers is
cheapest way, since the optical fiber itself is now about as
kite string and fishing line! (FTTx PON systems use one
fiber in two
directions so it can use one PON coupler transmitting and
lower system cost.) The link connects electronic signals
devices that need to communicate, just like a copper cable.
has a transmitter that converts electronic signals from
equipment to optics and a receiver that converts the signal
electronics at the other end.
optic transmitters use LEDs or semiconductor lasers to
electronic signals to optical signals. LEDs, similar to
everywhere for indicators, except transmitting in the
beyond human perception are used for slower links, up to
million bits per second (Mb/s), for example fast Ethernet
links use infrared semiconductor lasers because they have
bandwidth, up to tens of billions of bits per second (Gb/s).
have more power, so they can also go longer lengths, as in
plant applications such as long distance telecom or CATV.
As noted, transmitters use infrared light. Infrared light
loss in the fiber, allowing longer cable runs. Typically
glass fibers use light at 850 nm, referred to as "short
singlemode fiber operates at 1310, 1470 or 1550 nm, called
Since the light being transmitted through the optical fiber
the range of human sight, you cannot look at the end of a
tell if light is present. In fact, since some links carry
looking at the end of the fiber, especially with a
concentrates all the light into the eye, can be dangerous.
examining a fiber visually, always check with a power meter
no light is present unless you know the far end of the fiber
disconnected and use a microscope equipped with a laser
At the receiver end, a photodiode converts light into
current. Photodiodes must be matched to the transmitter
wavelength, power level and bit rate as well as the fiber
optimize performance. It's the receiver that ultimately
performance of the link, as it needs adequate power to
reliably. Receivers have a certain amount of internal noise
interfere with reception if the signal is low, so the power
optical signal at the receiver must be at a minimal level.
The power at the receiver is determined by the amount of
into the fiber by the transmitter diminished by the loss in
optic cable plant. The installer will test the cable plant
after construction, comparing it to a loss calculated from
component values called the "loss budget." Transmitter power
measured when the networking equipment is installed using a
attached to the transmitter.
Networks adapt the generic fiber optic link described above
specific network's needs. An Ethernet link will be optimized
bitrate and protocol of the version of Ethernet to be used,
Gigabit Ethernet. Video links may be analog or digital,
the camera, and may include camera controls in one direction
in the other. Industrial links may be based on RS-232 or
Most computer or telecommunications networks have adopted
fiber optic transmission as well as copper wiring and
However, sometimes the user has equipment with copper
wants to use fiber. Then they can use fiber optic media
which do exactly what their name suggests. Media converters
convert from one media to another, typically UTP copper to
fiber, coax to optical fiber or multimode to singlemode
converters are like transmitters and receivers in that they
specified for specific network applications to insure the
operation in that application.
Since so many link types exist, it is impossible to
generalize on fiber
optic link characteristics, but there
table in the FOA website detailing most standard networks.
When designing or installing fiber optic cabling, the
either design to cabling standards, which allows use with
or communications system designed for those standards, or
specific network, which may allow optimizing the cable
plant. If the
actual network to use the fiber optic cabling is not known,
plan is to design, install and the test cable plant based on
optic component specifications rather than any
Whatever you want to know about
fiber, you can probably find it on
Online Reference Guide To Fiber Optics
FOA Reference Guide to Premises Cabling (print version)
FOA Reference Guide To Fiber Optics (print version)
FOA Reference Guide To Outside Plant Fiber Optics (print
a PDF Version Of This
Page to Print for Reference
Here is a full explanation
of OM3/OM4 nomenclature.
fiber optic cables:
distribution, loose tube and breakout (from top)
Recommendation On Cabling Selection
we're seeing premises cabling, designed to carry gigabit and
traffic with 850 nm VCSEL transmitters, moving toward
on 50/125 laser-optimized fiber (now universally
called OM3 or OM4 for the two grades of available
standardized fiber) with LC connectors
to match the manufcturers' standard for VCSEL transceivers.
even has it's own color, aqua, specified in TIA-598.
you are planning, designing, installing or using high speed
fiber optic networks, it appears you should be recommending
OM3 or OM4 fiber and LC connectors. Within the industry,
this is becoming a
"de facto" standard known as "OM3 or OM4 cabling." One big
advantage of using
a full OM3 or OM4 cabling standard is that it is easily
identifiable by the
aqua color and cannot be interconnected with legacy cabling.
FOA is encouraging all FOA-Approved schools to adopt the OM3
nomenclature in their training. We've added this
recommendation to the
FOA User's Page and will add it to the NECA/FOA 301 standard
is the "OM3 Cabling "spec for designers to use in
The fiber optic cable plant will be type OM3 (or OM4)
cabling, using laser optimized (OM3 or OM4) fiber in a
cable with aqua colored
jacket, terminated with LC type connectors and mating
colored acqua. Individual fiber cable runs will be
specified by number
of fibers and cable type (riser, plenum, indoor-outdoor,
by the actual installation.
Checklist For Users Of Fiber Optic Communications Products
This is intended as an overview and installation checklist for
managers and engineers on the overall process of designing,
and operating a fiber optic communications system. Fiber
major advantages for communications systems including
distance and bandwidth. Proper application of fiber optic
will lead to highly reliable systems. But the user must choose
proper products, design and install an appropriate cable
make sure components are tested, all following appropriate
standards. This guide is designed to provide the information
to ensure proper installation and usage of fiber optic
references, we will use:
FOA Online Reference Guide To Fiber Optics
FOA Reference Guide To Fiber Optics (print version)
The FOA Reference Guide to Premises
Cabling (print version)
that these documents refer to other more detailed
documents such as TIA or ISO standards.
this document is primarily focused on the design,
maintenance of fiber optic cable plants, most end users will
interested in costs, so the FOA has a separate document on estimation.
Overview of Fiber Optic Network Design and Installation
the comprehensive FOA Tech Bulletin on Designing
Optic Networks. PDF 1.3 MB)
Select a communications module or converter that fits the data
you plan to transmit.
The first step is to choose the type of system needed. Fiber
communications products exist for almost every type of
system, from high speed telephone and CATV systems to simple
RS-232 or relay closure links. Many are media converters from
electrical interfaces like Ethernet that have various options
rates. Some are proprietary links for specialty equipment used
utility monitoring, industrial control, video surveillance,
Select a fiber optic product that is specified to work over
of your application. Note the type of fiber and other
as connectors required for this product.
a. Consider the range of the link as that affects the type of
b. Short links use multimode fiber and LED sources, while
use lasers and singlemode fibers.
c. Most fiber optic communications products offer several
cover different ranges.
d. Alternately, if you already have fiber optic cable plant
select a product that will operate over your fiber optic cable
considering both fiber type and distance.
Select a fiber optic cable type appropriate for the
Chapters 4,5 and NECA-301, Sec 5)
a. Determine the working environment of the fiber optic cable
Some applications are in office environments, some on factory
above ceilings and some are outdoors.
b. Outdoors, some cables are installed aerially, either lashed
messenger or self-supporting, some are buried directly or in
and some must run under water.
c. All outdoor cables require protection from water entry and
environmental factors particular to the installation.
d. Each application puts requirements on the cable design that
be discussed with cable manufacturers who can recommend cable
appropriate for that application.
e. Not all manufacturers make the same type of cable, so
several vendors may provide options in cables that affect
f. Consider installing several extra fibers in case any are
installation or if additional fibers are needed for future
(In fact, for critical applications, it may be advisable to
complete backup link and/or redundant fiber optic cable plant
run in a
g. Often singlemode fibers are added to multimode cables
hybrid cable) in case future networks need higher bandwidth.
h. At this stage, also decide on the installation hardware
as conduit or innerduct for buried cables and hangers or
Plan ahead on splicing requirements. (FOTN, Chapter 6 and
a. Long lengths of cables may need to be spliced, as fiber
is rarely made in lengths longer than several kilometers due
and pulling friction considerations.
b. If fibers need splicing, determine how to splice the fibers
or mechanical) and what kind of hardware like splice closures
appropriate for the application.
Choose connectors of a style and termination type
appropriately for the
application. (FOTN, Chapter 6 and NECA-301, Sec 6)
a. Cables will need terminations to interface with the
b. Connectors need to be chosen appropriately or patchcords
end terminated with connectors compatible with the
products will be needed.
c. Fiber optic connectors have several termination methods,
adhesives and polishing, some using splicing, which have
d. Discuss connectors with both manufacturers and installers
making this choice.
Ensure the calculated link loss is substantially less than the
margin of the communications products. (FOTN, Chapter 10 and
a. Calculate the power/loss
budget for the link.
b. Using typical component specifications and the design of
plant (type of fiber, length, transceiver wavelength, number
connectors and splices) you can calculate the approximate
loss of the cable plant
c. Compare it to the link margin for the communications
d. Discuss potential margin problems with communications
Install the cable plant. (FOTN, Chapters 9, 10,11, 12, 15 and
Sec 4 below )
a. Using the design developed in this process, install the
b. Some users learn to install and maintain the fiber optic
themselves, while others use contractors.
c. Installers or contractors should be trained and experienced
installation type being done, have references for previous
work and be certified
by independent organizations like The Fiber Optic Association.
d. Follow the guidelines in the NECA 301-2004 Standard For
and Testing Fiber Optic Cables, available from The National
e. Do not discard excess cable from the installation, but
store it for
future needs in restoration if the cable plant is damaged.
Test the cable plant for end-to-end optical loss. (FOTN,
Chapter 17 and
NECA-301, Sec 7)
the cable plant for optical loss according to industry
standards. Most cable plants are tested according to standards
TIA/EIA-526-14 for multimode fibers and TIA/EIA-526-7 for
fibers using Method B, with a one cable reference for 0dB
approximate loss expected before you begin testing.
b. Longer cables with splices should also be tested with an
verify splice quality.
c. Cables installed aerially or in areas of likely stress can
tested with the OTDR to verify installation quality.
any fibers that are high loss and correct the problem.
Install the communications products and test their operation.
a. After the cable plant is tested and known good, install the
optic communications equipment and test its operation.
b. Use any self-testing options to check operation, use BERT
rate test) equipment or transmit known data and look for
c. Once a network is operating properly, it should require no
maintenance in fact, attempted maintenance on premises
un-qualified personnel is often a cause of damage so it is
lock fiber optic component enclosures to reduce unauthorized
entry - a
requirement for class 4 (high power)lasers.
d. Outside plant networks may need frequent visual inspection
find damage or potential damage.
Document the fiber optic network. (FOTN, Chapter 13 and
NECA-301, Sec 8)
a. Perhaps the most important part of any installation is the
b. Accurate and complete documentation is invaluable in
troubleshooting or restoring a network. (Download the FOA Tech
Restoration" PDF, 90 kB) Documentation should include
identification of all components, the paths of each cable,
cable (and where the excess is stored for restoration), cable
lengths, locations of splices or terminations and the optical
each fiber measured at installation.
c. If OTDR traces are taken, those should be stored with the
d. Copies of all documentation should be kept at each end of
and backups stored in a safe place.
begins with a good blueprint.
Important Considerations in Fiber Optic Installation
Fiber optics offers major advantages for communications
including security, distance and bandwidth. Proper
application of fiber
optic technology will lead to highly reliable systems. That
user must install an appropriate cable plant and test every
all following appropriate industry standards. This guide is
provide to those directly involved in planning and
installing the fiber
optic network the information necessary to ensure proper
and usage of fiber optic systems.
- Every project needs "paperwork" to define the
project for both the user and the contractor. See the FOA
page on Paperwork for a rundown of the important
documents and what they mean.
- This list only concerns
itself with the project steps unique to fiber
optic systems, but many OSP applications require obtaining
easements or rights-of-way. That is beyond the scope of
Do a complete design before beginning cable plant
Chapter 9 and NECA-301)
a. Establish criteria for the install, based on the
b. Know how many fibers of what types are needed add
repairs or growth
c. Determine hardware requirements: connectors, splices,
d. Plot the cable route and determine cable lengths
e. Show how installed (premises, buried, conduit, innerduct,
underwater, pole locations for aerial, etc.)
f. Mark termination and splice points
g. Attach data from link loss budget and use it as a guide
h. Don't try to build a marginal design allow for
i. Follow the NECA 301-2004 Standard For Installing and
Optic Cables in design and installation
j. At the same time, design the facilities for the
equipment, including locations, allowing for adequate
spaces, power and
grounding and HVAC as needed
k. Make complete lists of what components and hardware are
where they are to be used
Work with vendors on component specs to get best quality and
a. Vendors usually have suggestions on components like
hardware that can facilitate design and implementation, but
several opinions and compare their suggestions to what you
you need .
b. Consider options like pre-terminated cables or air-blown
short indoor cable runs
c. Remember to plan for purchasing overages on components to
extra cable for restoration or extra connectors necessary
due to yields
d. Be careful of industry or manufacturer "jargon" as not
the same term in fiber optics
Once you have a design and component pricing, you can do a
Have all components available before beginning installation
may complete the installation promptly and properly.
a. Inventory everything received
b. Check for shipping damage
c. Store in a safe, dry place until used
d. Separate as needed for each work site
e. While at the job site, consider using guards if
components are left
Use only trained, qualified installers, preferably
a. Installing fiber optics is not difficult, but has special
familiar to those with experience
b. Make sure the installers are experienced in the type of
you are planning, as installers often specialize in aerial,
or even singlemode installation
c. Look for FOA
CFOT certification (www.thefoa.org) and good
d. Review the design with the installer to familiarize them
job and see if they have advice on how to make it easier or
use your judgement regarding any changes suggested.
issues and establish rules for the installation.
Chapter 11 and NECA-301, Sec 3)
a. All installers and supervisors should be briefed on
b. Ensure that you have copies of the documentation
contractors bonding, insurance, workers compensation, OSHA
c. Use NECA 301-2004 Standard, Section 3 plus any applicable
Install the cable plant. (FOTN, Chapter 15 and NECA-301, Sec
a. NECA 301, Section 5.4 offers good guidelines for
b. Watch for proper handling to prevent cable damage,
tension and bend radius
c. Long lengths (>200m) can be tested by an experienced
technician with an OTDR after installation but before
termination if there is any question about potential damage
installation. Remember OTDR testing is optional, but every
requires insertion loss testing with a meter and source.
d. Install the hardware: NECA 301, Section 5.5
e. Splice as needed: NECA 301, Section 6.3, generally use
splicing in outside plant and singlemode applications,
splices limited to premises multimode cables
f. Terminate ends: NECA 301, Section 6.2, generally
connectors will be installed on the cables directly while
connectors will use pre-terminated pigtails to reduce loss
reflection which are both important to laser transceivers
singlemode fiber, especially in short links (~<2 km)
g. All splices and terminations should be placed in
hardware for protection
h. Remember to clean
connectors properly and keep dust caps on all
i. All fiber optic cables should be color-coded by jacket
and/or marked with orange or yellow tags or whatever color
designated for your cable plant to identify it as fiber
j. Carefully mark all cables and connections for
identification in a
manner consistent with the company documentation processes.
k. Dust caps from the connectors and couplings terminated in
enclosure belong to that enclosure and should be put in a
bag and taped inside the cabinet for future use.
Test and troubleshoot the cable plant. (FOTN, Chapter 17 and
Sec 7, 4
Ways To Test An Installed Cable Plant) and Troubleshooting
cable plants and communcations systems, Testing
All cable plants must be tested for insertion
loss per industry standards (TIA/EIA-526-14 for
TIA/EIA-526-7 for singlemode fibers) at the wavelength(s) to
with the transmission systems chosen
b. Insertion loss must be less than allowable link loss
margin for the
communications equipment being used on the fibers
c. Longer cable plants, especially singlemode and those
should be tested by an experienced technician with an OTDR
splice loss and confirm the cable was not damaged during
advice on using OTDRs properly.)
d. Remember to clean
connectors properly and keep dust caps on all
e. All test data should be recorded for cable plant
saved for future troubleshooting and restoration
Install the communications systems.
a. Install all the active devices according to
specifications and test for proper operation
b. If patchcords are used for connecting optical ports to
plant, use tested patchcords that are known to be in good
Patchcords must match
fiber in the cable plant being tested to prevent
all connectors after removing dust caps and before
to transceivers or cable plant connectors
d. Using an optical power meter and good reference test
transmitter power levels to ensure it is within
e. Using an optical power meter, test receiver power levels
it is within manufacturer's specifications (you can use
pieces of data to calculate the loss of the cable plant
use, which should correlate with insertion loss test data
using a test
f. If the power exceeds the receiver dynamic range and
reduce the power by using attenuators of a type recommended
equipment manufacturer placed at the receiver, checking with
optical power meter to ensure the lower power level is in an
Document the fiber optic network. (FOTN, Chapter 13 and
NECA-301, Sec 8)
a. Perhaps the most important part of any installation is
documentation. Good documentation is invaluable in
troubleshooting or restoring a network
b. Documentation should include:
i. Design data, e.g. CAD drawings and maps
ii. Component types and manufacturers
iii. The paths of each cable
iv. Types of cable (and where the excess is stored for
v. Cable section lengths
vi. Locations of splices or terminations
vii. Calculated loss budget
viii. The optical loss of each fiber measured at
ix. Fiber numbers/colors connected to each communications
noting transmitter and receiver orientation
x. Spare fibers available for expansion or use to replaced
xi. Types of communications equipment
xii. Wavelength of transmission
xiii. Transmitter and receiver power for each transceiver
attenuator values if used)
xiv. OTDR traces if taken
xv. Name and contact information for installers
c. Copies of the documentation should be kept at each end of
and backups stored in a safe place.
Fiber optic premises networks generally do not require
a. As long as the network is communicating as expected, no
should be required and the network should not be touched
communications equipment is moved, added or changed.
b. Attempts at inspection or maintenance are a major cause
of damage to
cables or connectors and getting dirt into components
c. Hardware should be lockable to prevent unauthorized entry
d. Outdoor installations, being more prone to mechanical and
environmental damage should be visually inspected for damage
as part of
a regularly scheduled preventative maintenance program.
a PDF Version Of This
it as a guide to create a work plan for your network
it into your RFP/RFQ
copies for your managers employees, contractors,
give us your feedback. Contact
the FOA. If you are planning a fiber optic
system, we'll send you a free copy of the NECA-301
For Installing And Testing Fiber Optic Cables.