1. OFC
An optical fiber cable is a cable containing one or more optical
fibers that are used to carry light. The optical fiber elements are
typically individually coated with plastic layers and contained in a
protective tube suitable for the environment where the cable will be
deployed. Different types of cable are used for different applications,
for example long distance telecommunication, or providing a high-
speed data connection between different parts of a building.
2. Design
• Optical fiber consists of a core and a cladding layer, selected
for total internal reflection due to the difference in
the refractive index between the two. In practical fibers, the
cladding is usually coated with a layer of acrylate
polymer or polyimide. This coating protects the fiber from
damage but does not contribute to its optical
waveguide properties.
3. Fiber Optic Tutorial
• What are Fiber Optic Cables?
Fiber optic cables consist of a glass core and cladding, buffer
coating, Kevlar strength members and a protective outer jacket.
Fiber optic cables use light pulses as opposed to electrical signals to
send information.
• How are Fiber Optic Cables used?
Fiber optic cables can be plugged into communications equipment
and patch panels to provide a physical connection to a network or
device.
• Where are Fiber Optic Cables used?
Fiber optic cables are used by commercial business, governments,
the military and many other industries for myriad applications
involving the transmission of voice, video and data.
4. Fiber Optic Terms
• Absorption: One cause of attenuation where light signal is absorbed into the glass during transmission.
• Attenuation: Optical loss of power. Attenuation is measured in dB loss per length of cable. Attenuation is
usually caused by absorption and scattering.
• Attenuator: A device used to reduce the power of an optical signal.
• Back Reflection: A measure of the light reflected off the polished end of a fiber connector. Measured in
negative dB relative to incident power.
• Bandwidth: The range of signal frequencies that a fiber optic cable will transmit.
• Buffer: The protective coating over the fiber.
• Insertion Loss: The attenuation caused by the insertion of a device (such as a splice or connection point)
to a cable.
• Loss Budget: The maximum amount of power that is allowed to be lost per optical link.
• Multimode: A type of fiber optic cable where the core diameter is much larger than the wavelength of
light transmitted. Two common multimode fiber types are 50/125 and 62.5/125.
• Return Loss: The ratio of the power launched into a cable and the power of the light returned down the
fiber. This measurement is expressed in positive decibel units (dB). A higher number is better. Return Loss
= 10 log (incident power / returned power).
• Scattering: A second cause of attenuation. Scattering occurs when light collides with individual atoms in
the glass.
• Single mode: A type of fiber with a small core that allows only one mode of light to propagate.
• Wavelength: A means of measuring light color. Expressed in nanometers (nm).
5. Fiber Core Sizes
• Fiber specifications list the core and cladding diameters as a ratio.
Multimode fiber is commonly 62.5/125 or 50/125 micron, single mode
fiber is commonly 9/125 micron.
9. Simplex and zip cord
These types are used mostly
for patch cord and backplane
applications, but zipcord can
also be used for desktop
connections. Simplex cables
are one fiber, tight-buffered
(coated with a 900 micron
buffer over the primary buffer
coating) with Kevlar (aramid
fiber) strength members and
jacketed for indoor use. The
jacket is usually 3mm (1/8 in.)
diameter. Zipcord is simply
two of these joined with a thin
web.
10. Distribution cables
Distribution cable is the most popular
indoor cable, as it is small in size and light
in weight. They contain several tight-
buffered fibers bundled under the same
jacket with Kevlar strength members and
sometimes fiberglass rod reinforcement to
stiffen the cable and prevent kinking.
These cables are small in size, and used
for short, dry conduit runs, riser and
plenum applications. The fibers are double
buffered and can be directly terminated,
but because their fibers are not
individually reinforced, these cables need
to be broken out with a "breakout box" or
terminated inside a patch panel or
junction box to protect individual fibers.
11. Breakout cables
Breakout cable is a favorite where rugged cables
are desirable or direct termination without
junction boxes, patch panels or other hardware
is needed. They are made of several simplex
cables bundled together insdie a common
jacket. This is a strong, rugged design, but is
larger and more expensive than the distribution
cables. It is suitable for conduit runs, riser and
plenum applications. It's perfect for industrial
applications where ruggedness is needed.
Because each fiber is individually reinforced, this
design allows for quick termination to
connectors and does not require patch panels or
boxes. Breakout cable can be more economic
where fiber count isn't too large and distances
too long, because is requires so much less labor
to terminate.
12. Loose tube cables
Loose tube cables are the most widely used cables
for outside plant trunks because it offers the best
protection for the fibers under high pulling tensions and
can be easily protected from moisture with water-
blocking gel or tapes.These cables are composed of
several fibers together inside a small plastic tube, which
are in turn wound around a central strength member,
surrounded by aramid strength members and jacketed,
providing a small, high fiber count cable. This type of
cable is ideal for outside plant trunking applications, as it
can be made with the loose tubes filled with gel or
water absorbent powder to prevent harm to the fibers
from water. It can be used in conduits, strung overhead
or buried directly into the ground. Some outdoor cables
may have double jackets with a metallic armor between
them to protect from chewing by rodents or kevlar for
strength to allow pulling by the jackets. Since the fibers
have only a thin buffer coating, they must be carefully
handled and protected to prevent damage. Loose tube
cables with singlemode fibers are generally terminated
by spicing pigtails onto the fibers and protecting them in
a splice closure. Multimode loose tube cables can be
terminated directly by installing a breakout kit, also
called a furcation or fan-out kit, which sleeves each fiber
for protection.
13. Ribbon Cable
Ribbon cable is preferred where high fiber
counts and small diameter cables are
needed.This cable has the most fibers in
the smallest cable, since all the fibers are
laid out in rows in ribbons, typically of 12
fibers, and the ribbons are laid on top of
each other. Not only is this the smallest
cable for the most number of fibers, it's
usually the lowest cost. Typically 144
fibers only has a cross section of about
1/4 inch or 6 mm and the jacket is only 13
mm or 1/2 inch diameter! Some cable
designs use a "slotted core" with up to 6
of these 144 fiber ribbon assemblies for
864 fibers in one cable! Since it's outside
plant cable, it's gel-filled for water
blocking or dry water-blocked. Another
advantage of ribbon cable is Mass Fusion
Splicers can join a ribbon (12 fibers) at
once, making installation fast and easy.
Ribbon pigtails are spliced onto the cable
for quick termination.
14. Armored Cable
• Armored cable is used in direct
buried outside plant applications
where a rugged cable is needed
and/or rodent resistance. Armored
cable withstands crush loads well,
needed for direct burial applications.
Cable installed by direct burial in
areas where rodents are a problem
usually have metal armoring between
two jackets to prevent rodent
penetration. Another application for
armored cable is in data centers,
where cables are installed underfloor
and one worries about the fiber cable
being crushed. Armored cable is
conductive, so it must be grounded
properly.
15. Aerial cable
Aerial cables are for
outside installation on
poles. They can be lashed
to a messenger or
another cable (common
in CATV) or have metal or
aramid strength members
to make them self
supporting. The cable
shown has a steel
messenger for support. It
must be grounded
properly.
16. Hybrid and Composite Cables
These two types of cables are
often confused, but almost
everybody and the NEC defines
them as:
• Hybrid cables: Cables that
contain two types of fibers,
usually multimode and
singlemode. These cables are
often used in campus and
premises backbones where the
singlemode fibers may be used in
the future.
• Composite cables: Cables that
contain both fibers and electrical
conductors. Underwater tethered
vehicles use cables like this, as do
some cables used for remoting
wireless antennas or CCTV
cameras. These cables must be
properly grounded and bonded
for safety.01244414888
