Splices , Connectors and Couplers in Optical Fibre. Presentation describes all of the types of these

1. Splices Connectors & Couplers

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Topic Page
Number
1 . Optical Fibre 3
2 . Splices 4
3 . Connectors 8
4 . Couplers 11
5 . Splitters And Connectors 16

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An optical fiber or optical fibre is a flexible, transparent fiber made by drawing
glass (silica) or plastic to a diameter slightly thicker than that of a human hair.
Optical fibers are used most often as a means to transmit light between the
two ends of the fiber and find wide usage in fiber-optic communications,
where they permit transmission over longer distances and at higher
bandwidths (data rates) than electrical cables. Fibers are used instead of metal
wires because signals travel along them with less loss; in addition, fibers are
immune to electromagnetic interference, a problem from which metal wires
suffer excessively. Fibers are also used for illumination and imaging, and are
often wrapped in bundles so they may be used to carry light into, or images
out of confined spaces, as in the case of a fiberscope. Specially designed fibers
are also used for a variety of other applications, some of them being fiber
optic sensors and fiber lasers.
Optical fibers typically include a core surrounded by a transparent cladding
material with a lower index of refraction. Light is kept in the core by the
phenomenon of total internal reflection which causes the fiber to act as a
waveguide.

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Rather than using optical fibre connectors, it is possible to splice two optical fibres
together. An fibre optic splice is defined by the fact that it gives a permanent or
relatively permanent connection between two fibre optic cables. That said, some
manufacturers do offer fibre optic splices that can be disconnected, but nevertheless
they are not intended for repeated connection and disconnection.
There are many occasions when fibre optic splices are needed. One of the most common
occurs when a fibre optic cable that is available is not sufficiently long for the required
run. In this case it is possible to splice together two cables to make a permanent
connection. As fibre optic cables are generally only manufactured in lengths up to about
5 km, when lengths of 10 km are required, for example, then it is necessary to splice two
lengths together.
Fibre optic splices can be undertaken in two ways:
• Mechanical splices
• Fusion splices

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Types of splicing
Mechanical Splice
A mechanical splice is a junction of two or more optical
fibers that are aligned and held in place by a self-
contained assembly (usually the size of a large carpenter's
nail).The fibers are not permanently joined, just precisely
held together so that light can pass from one to another.
Fusion Splice
Fusion splicing is the act of joining two optical fibers end-
to-end using heat. The goal is to fuse the two fibers
together in such a way that light passing through the
fibers is not scattered or reflected back by the splice, and
so that the splice and the region surrounding it are almost
as strong as the intact fiber. The source of heat is usually
an electric arc, but can also be a laser, or a gas flame, or a
tungsten filament through which current is passed

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1. Locate the Damaged
Area
2. Unplug from
receptacle or switch off
at circuit breaker box
3. Discard The Damaged
Area Of the Wire
4. Remove insulation
from the 2 newly created
ends of the wires.
5. Form the wires. 6. Place heat shrink
tubing.

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7. Align the wires and connect the
wires with crimp-type connectors
or by twisting.
8. Prime the soldering iron.
9. Solder the wires. 10. Insulate the splice.

8. An optical fiber connector terminates the end of an optical fiber, and enables quicker
connection and disconnection than splicing. The connectors mechanically couple and
align the cores of fibers so light can pass. Better connectors lose very little light due to
reflection or misalignment of the fibers. In all, about 100 different types of fiber optic
connectors have been introduced to the market.
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9. Application of Connectors
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Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the
polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are often
assembled onto optical fiber in a supplier’s manufacturing facility. However, the assembly and polishing operations
involved can be performed in the field, for example, to terminate long runs at a patch panel.
Optical fiber connectors are used in telephone exchanges, for customer premises wiring, and in outside plant
applications to connect equipment and cables, or to cross-connect cables.
In many data center applications, small (e.g., LC) and multi-fiber (e.g., MTP/MPO)
connectors have replaced larger, older styles (e.g., SC), allowing more fiber ports per
unit of rack space and higher data rate application such as 100 Gigabit Ethernet.
Features of good connector design:
• Low insertion loss
• High return loss (low amounts of reflection at the interface)
• Ease of installation
• Low cost
• Reliability
• Low environmental sensitivity
• Ease of use

10. Types of Connectors
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A variety of optical fiber connectors
are available, but SC and LC
connectors are the most common
types of connectors on the market.
Typical connectors are rated for 500–
1,000 mating cycles. The main
differences among types of
connectors are dimensions and
methods of mechanical coupling.
Generally, organizations will
standardize on one kind of connector,
depending on what equipment they
commonly use.

11. An optical coupler takes traffic from an input port or connection and directs it, over a fabric, to an output
port. Existing electronic couplers handle variable-length packets, fixed-length cells, and synchronous time
slots to perform these operations. An optical coupler, on the other hand, works with light and is used to
direct a single wavelength, or perhaps a range of wavelengths, from input port to output port . The all-
optical couplers and splitters are more recent development. These are all-analog device, where both the
input/output modules and the backplane are optical ones. The primary benefit of all-optical devices may
be their greater scalability over electronic devices.
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In splitting function, the fiber optic coupler split the input signal
in two or more outputs. Such types of couplers are known as
optical splitters. On the other hand, optical combiners are used
to combine two or more inputs into one single output.
Fiber optic coupler can be classified as Y couplers and T couplers .
Y type of coupler is also called optical tap coupler. Such couplers
are used to divide the power in to two outputs. However power
distribution ratio has to control precisely in order to generate
user or application specific coupling function like in the ratio of
10:90 percent, 20:80 percent, 30:70 percent, 40:60 percent or
50:50 percent.
The basic operation of a T coupler is also same as
for Y coupler. T couplers can be cascaded to
connect multiple terminals on a network, as
shown in figure 2.1 (b). In such type of couplers,
the split ratio must be maintained either 10:90
percent or 20:80 percent, so that power to next
stage can coupled efficiently. Generally T
couplers are used in small networks, where port
counts are less.

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Depending upon the operating principles, fiber optic
couplers can be classified into active or passive
category.
In Passive Couplers, optical signal to electrical signal
conversion is not needed for distribution of optical
signals among the output fibers. Typically it consist of
N input ports and M output ports, where value of N
and M ranges from 1 to 64. The selection of number
of input ports and output ports depends upon its
uses, i.e. applications in which passive couplers has to
used.In generic passive couplers, micro-lenses,
graded-refractive-index (GRIN) rods, beam splitters,
optical mixers, splices and the optical fibers with
fused core are used. That is why; fabricating the
passive fiber optic coupler is difficult and requires
cumbersome process.
Active Couplers split or combine the signal
electrically and use optical detectors and sources for
input and output. Therefore active fiber optic
couplers require an external power source. They
receive input signal(s), and then use a combination
of fiber optic detectors, optical-to-electrical
converters, and light sources to transmit fiber optic
signals.

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While in a non-directional type of star coupling
device, a signal applied to any fiber appears at all
other remaining fibers.
With use of reflective mirrors, such couplers can
be used to work as directional reflective star
couplers.
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A star coupler generally has several input and output port combination, in which the optical power is distributed
from more than two input ports among several output ports. The number of input and output port may or may
not be equal in star couplers such as 2×4, 4×4, 8×16, etc. However in all possible input and output port
combinations, the distribution of power among the output ports remains equal.A star coupler can further
classified as Directional and Non-directional star coupler.
Beside Figure depicts a directional type star coupler, in which
initially mixing of all input signal is done and then the
collected power is equally transferred to the output ports. If
the transmission in a star coupler is possible in both
directions, then they can be further classified as bidirectional
coupling devices.

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Depending upon the number of input and outputs, tree
coupler is used to splits or combines the optical power from
input fibers to output fibers. Star and tree couplers
distribute the input power uniformly among the output
fibers.During operation it is desirable that fiber optic
couplers should transfer (coupled) the optical power to the
desired output fiber only and should by pass all other
(undesired) output fibers. Directional couplers are better
known for transfer of optical through coupling mechanism
in such manner.
Depending upon the capability, the couplers can be categorizing as Symmetrical and Unsymmetrical couplers. In
symmetrical couplers, transfer of equal amount of optical power is possible even if the input and output ports
are changed with each other, i.e. for reverse operation, the coupling efficiency remain same. “Tree couplers have
been extensively used to split and mix optical signals in CATV, LANs and all other kinds of optical communication
systems”. For higher port networks (requiring more than 3 or 4 terminals), star couplers are better to use in place
of cascaded T coupler, as they possess lower excess losses as compared to T couplers for similar kind of
operation.

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An optical splitter is also a passive device, which is used to divide
the optical power and transmit to two adjacent fibers. Basically ,
the splitter divides the optical power into two equal parts among
the fibers. Also it can be used to divide the incident optical power
into unequal powers depending upon the structuring of the
splitting section or operating principle. Even a splitter can be
made to split the power in such a way, that the split power may
appear at one output port and a very small portion it coupled to
the other output port. This type of optical splitter is known as a
T-coupler, or an optical tap.
An optical combiner is a passive device that
combines the optical power carried by two input
fibers into a single output fiber.An X junction
waveguiding structure is used to combines the
functions of the optical splitter and combiner.
Such type of coupler usually has two inputs and
two outputs, also termed as the 2×2 Coupler.

17. Prepared By -
Ved Mishra - 1629115
Aman Kumar - 1629126
Palav Anand - 1629149
Ritwik Saurabh - 1629163
Sachin Bhardwaj - 1629165
Shiwangi Singh - 1629174
11/10/2018 17Opitical Splices , Connectors And Couplers