Understanding the basics of optical fibers

UNRAVELLING FIBERS AND FIBER TO THE HOME
A Project Report
Submitted in partial fulfillment of requirement for the award of the degree of

Bachelor of Technology

Submitted By:
Vanhishikha Bhargava
(Roll No: 0941631056)

Under the Supervision of
Mr. Vinod C.P
(Technical and Business Development Head)
Advanced Fiber Systems Pvt. Ltd.
No. 137/ 2, Service Road, Outer Ring Road
Banaswadi, Kalyan Nagar Post
Bangalore - 560043

Department of Electronics and Communication
G.N.I.T. (Girls) GREATER NOIDA
Session 2012-2013

1

INDEX
Basics of Fiber Optics and its Evolution

01

Color Coating

05

Understanding wavelengths

06

Types of Optical Fibers

11

Advantages and Disadvantages of Optical Fibers

14

Applications of Optical Fibers

15

ITU- T Standards

16

Connectors and its Types

20

Polishing and its Types

27

Adapters and its Types

29

Attenuators and its Types

34

FTTH – Customer Premises

38

Cables and its Types

39

Losses in Optical Fibers

56

Splitters and its Types

66

Field Assembly Connectors

70

Splicing and its Types

72

Wavelength Division Multiplexing

75

Conclusion

77

Bibliography

78

2

DECLARATION

I hereby declare that this project report entitled, ―Unravelling Fibers and Fiber To The Home‖, has
been prepared by me during the academic year 2012-13, under the guidance and supervision of Mr.Vinod
C.P (Technical and Business Development Head).
I also declare that this project is the result of my own efforts and the information is collected from the
company’s records and the conclusion is arrived after discussing with the project head and other staff.

Date: 24-07- 2012
Place: Greater Noida

Signature of the Candidate
(Vanhishikha Bhargava)

3

ACKNOWLEDGEMENT
I would like to express my deep sense of gratitude to the department of Electronics and Communication,
Greater Noida Girls Institute of Technology, GautamBuddh Technical University, for giving an
opportunity to do this training which helped me to understand the real working environment.

First and for most, I would like to express my deep sense of gratitude to Mr. Shanbhag RV ( Technical
Director) and Mr. Vijay Kumar HP (Business Development Director) , who have been a source of
inspiration throughout my course their guidance and advice have made this work possible.

I am very grateful to Mr. Vinod C.P (Technical and Business Development Head) for his advice and
guidance throughout this project.

I sincerely thank Mr. Anantha B.N, Mrs. Vimala S.V, and other employees for their co-operation,
without them my study would not have been a success.

I also wish to present my gratitude to my parents, and all my friends who have directly and indirectly
helped to bring out this project report.

VANHISHIKHA BHARGAVA

4

COMPANY PROFILE
AFS is a Bangalore based original equipment manufacturer.
We provide full range of passive products for network management. We manufacture, distribute and supply fiber optic
products that telecom service providers require for high speed, scalable and reliable voice ,video and data services.
AFS is expanding through its relentless efforts, aimed at providing true value to the wide segments of telecom and
enterprise businesses all across the globe.

Our Vision
To be a leading manufacturer of full line fiber optic interconnect products and fiber management solutions for the
telecommunication industry, as well as being an active contributor in the establishment of telecom infrastructure in the
country.

Our Mission
To distinguish ourself as a customer driven company, providing genuine concern and competent products/services to
our valued customers. We will also ensure total customer satisfaction.

Production Team
Backed by a strong drive for research and development, our production team is an amalgamation of technical
expertise and proprietary technological expertise to provide the telecom service providers the best in
Quality
Technology
Reliability and
Design aesthetics.
Our main strength is this team of highly motivated and qualified designers, researchers and engineers with a high
level of knowledge and dedication.
We believe in keeping close contact with world renowned academic institutions, other industry leaders and experts for
understanding the evolving industry requirements.

5

AFS GREEN POLICY
Our green policy is based on providing efficient and eco-friendly practices and products, which upon
usage and disposal will have minimal impact on the environment.
We are committed to apply the best green practices and strive to provide eco sustainability in all the
activities we undertake.
We are committed towards reducing our carbon footprint and improving out green credentials.

Our GREEN COMMITMENT stands for –
1. Energy conservation.
Use of energy efficient lighting (CFL)
Use of public transportation or taking a walk instead of using a car
Working with other green businesses
2. 3Rs’ –
-

Reduce Waste

-

Reduce material

-

Recycle waste
By reducing waste we try to optimise the full use of a product in its life cycle. Use of digital and
electronic and digital communication before using print or paper based communication. Thus,
promoting a PAPERLESS office in the long run.
By reusing paper, we ensure that our carbon footprint is minimised. All waste papers are disposed
through recycling only and using them on both sides.
For recycling, we work with NGOs to ensure that we have zero discharge to the landfill.

6

INTRODUCTION TO OPTICAL FIBRES
ORIGIN OF OPTICAL FIBRES
Optical communication systems date back two centuries, to the ―OPTICAL TELEGRAPH" invented by
French engineer Claude Chappe in the 1790s. His system was a series of semaphores mounted on towers,
where human operators relayed messages from one tower to the next. It beat hand-carried messages hands
down, but by the mid 19th century, it was replaced by the electric telegraph, leaving a scattering of
―telegraph hills‖ as its most visible legacy.
In the 1840s, physicist Daniel Collodo and Jacques Babinet showed that light could be directed along jets
of water for fountain displays. In 1854, John Tyndall, a British physicist, demonstrated that light could
travel through a curved stream of water thereby proving that a light signal could be bent. He proved this
by setting up a tank. He proved this by setting up a tank of water with a pipe that ran out of one side. As
water flowed from the pipe, he shone a light into the tank into the stream of water. As the water fell, an
arc of light followed the water down.
Alexander Graham Bell patented an optical telephone system, which he called PHOTOPHONE, in 1880,
but his earlier invention, the telephone , proved far more practical. He dreamed of sending signals through
air, but the atmosphere did not transmit light as reliably as wires carried electricity.
In the intervening years, new technology that would ultimately solve the problem of optical transmission
slowly took root, although it was a long time before it was adapted for communications. This technology
depended on the phenomenon of TOTAL INTERNAL REFLECTION, which can confine light in a
material surrounded by other material with lower refractive index such as glass and air .Optical fibers
went a step further. They are essentially transparent rod glass or plastic stretched to be long and flexible.

7

BASICS OF OPTICAL FIBRES
Optical fiber is a medium in which communication signals are transmitted from one location to another in
the form of light through thin fibers of glass or plastic. These signals are digital pulses or continuously
modulated analog streams of light representing information. These can be voice information, data
information, computer information, video information or any other type of information. This same type of
information can be sent on metallic wires such as twisted pair and coax (coaxial cables) and through the
air on microwave frequencies.
Total Internal Reflection
Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium
boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If
the refractive index is lower on the other side of the boundary and the incident angle is greater than the
critical angle, no light can pass through and all of the light is reflected. The critical angle is the angle
of incidence above which the total internal reflection occurs.
When light crosses a boundary between materials with different kinds of refractive indices, the light
beam will be partially refracted at the boundary surface, and partially reflected. However, if the angle
of incidence is greater (i.e. the ray is closer to being parallel to the boundary) than the critical angle –
the angle of incidence at which light is refracted such that it travels along the boundary – then the light
will stop crossing the boundary altogether and instead be totally reflected back internally. This can
only occur where light travels from a medium with a higher [n1=higher refractive index] to one with a
lower refractive index [n2=lower refractive index]. For example, it will occur when passing from glass
to air, but not when passing from air to glass.

If you have ever half-submerged a straight stick into water, you have probably noticed that the stick
appears bent at the point it enters the water. This optical effect is due to refraction. As light passes
from one transparent medium to another, it changes speed, and bends.Each medium has a different
refractive index. The angle between the light ray and the normal as it leaves a medium is called the
angle of incidence. The angle between the light ray and the normal as it enters a medium is called the
angle of refraction.

8

Snell’s Law
Snell's law(law of refraction) is a formula used to describe the relationship between the angles of
incidence and refraction, when referring to light or other waves passing through a boundary between
two different isotropicmedia, such as water and glass.
Refraction of light occurs at the interface between two media of different refractive indices, with n2> n1.
Since the velocity is lower in the second medium (v2< v1), the angle of refraction θ2 is less than the angle
of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.In optics, the law is
used in ray tracing to compute the angles of incidence or refraction.
Snell's law states that the ratio of the sines of the angles of incidence and refraction is equivalent to the
ratio of phase velocities in the two media, or equivalent to the opposite ratio of the indices of
refraction:

With each as the angle measured from the normal, as the velocity of light in the respective
medium (SI units are meters per second, or m/s) and as the refractive index (which is unit less) of
the respective medium.

9

Numerical Aperture
Fibers are labeled by their numerical apertures. The numerical aperture takes into account not only
the cone of acceptance, but the effect on that cone of different media outside the fiber.
We can find the cut-off angle θ0max by working backward from the point where light strikes the upper
edge of the fiber. In order for total internal reflection (TIR) to occur, the angle at this edge must be
greater than the critical angle:
θ1>θc
θ'1 is defined as the angle the light makes with respect to the normal at the entrance (left side) of the
fiber. Looking at the figure, we see that θ'1 and θ1 are complementary. Thus
θ'1< 90 - θc.
Snell's law applies at the entrance to the fiber, so
n0 sin θ0 = n1 sin θ1<n1 sin (90 - θc)
n0 sin θ0max = (n12 - n22)1/2 = NA

Rayleigh Scattering
Rayleigh scattering, named after the British physicist Lord Rayleigh, is the elastic scattering of light
or other electromagnetic radiation by particles much smaller than the wavelength of the light. The
particles may be individual atoms or molecules. It can occur when light travels through transparent
solids and liquids, but is most prominently seen in gases. Rayleigh scattering is a function of the
electric polarizability of the particles.
Rayleigh scattering is an important component of the scattering of optical signals in optical fibers.
Silica fibers are disordered materials, thus their density varies, on a microscopic scale. The density
fluctuations give rise to energy loss due to the scattered light, with the following coefficient

wheren is the refraction index, is the photo elastic coefficient of the glass, is Boltzmann constant,
and is the isothermal compressibility. Tf is a fictive temperature, representing the temperature at
which the density fluctuations are "frozen" in the material.

10

Fresnel’s Reflection

When light moves from a medium of a given refractive indexn1 into a second medium with refractive
index n2, both reflection and refraction of the light may occur. The Fresnel equations describe what
fraction of the light is reflected and what fraction is refracted (i.e., transmitted). They also describe the
phase shift of the reflected light.
The relationship between these angles is given by the law of reflection:

andSnell's law:

The fraction of the incident power that is reflected from the interface is given by the reflectanceR and
the fraction that is refracted is given by the transmittanceT. The media are assumed to be nonmagnetic.

11

COLOR COATING USING EIA-TIA STANDARDS
Each fiber is distinguishable by means of color-coding in accordance with TIA/EIA-598A,
―Optical Fiber Cable Color Coding". All fibers and buffer tubes are color coded to facilitate individual
fiber identification. The individual fiber colors used in loose tube cable are given in the following table:

TUBE

COLOR

1

BLUE (BL)

2

ORANGE

(OR)

3

GREEN (GR)

4

BROWN (BR)

5

SLATE (SL)

6
7

WHITE

(WH)

RED (RD)

8

BLACK

9

YELLOW

(BK)
(YW)

10

VIOLET(VI)

11

ROSE(RS)

12

AQUA (AQ)

12

Understanding Wavelengths in Fiber Optics

Fiber optics is full of jargon but it's important to understand it. One of the more confusing terms to
many is "wavelength." It sounds very scientific, but it is simply the term used to define what we think
of as the color of light.
Light is part of the "electromagnetic spectrum" that also includes x-rays, ultraviolet radiation,
microwaves, radio, TV, cell phones, and all the other wireless signals. They are simply
electromagnetic radiation of different wavelengths. We refer to the range of wavelengths of
electromagnetic radiation as a spectrum. Wavelength and frequency are related, so some radiation is
identified by its wavelength while others are referred to by their frequency. For the radiation of shorter
wavelengths, light, UV and x-rays, for example, we generally refer to their wavelength to identify
them, while the longer wavelengths like radio, TV and microwaves, we refer to by their frequency.

For fiber optics with glass fibers, we use light in the infrared region which has wavelengths longer
than visible light, typically around 850, 1300 and 1550 nm. The attenuation of glass optical fiber is
caused by two factors, absorption and scattering. Absorption occurs in several specific wavelengths
called water bands due to the absorption by minute amounts of water vapor in the glass.
Scattering is caused by light bouncing off atoms or molecules in the glass. It is strongly a function of
wavelength, with longer wavelengths having much lower scattering. Have you ever wondered why the
sky is blue? It's because the light from the sun is more strongly scattered in the blue.
Fiber optic transmission wavelengths are determined by two factors: longer wavelengths in the
infrared for lower loss in the glass fiber and at wavelengths which are between the absorption bands.
Thus the normal wavelengths are 850, 1300 and 1550 nm. Fortunately, we are also able to make
transmitters (lasers or LEDs) and receivers (photo detectors) at these particular wavelengths.
If the attenuation of the fiber is less at longer wavelengths, why don't we use even longer
wavelengths? The infrared wavelengths transition between light and heat, like you can see the dull red

13

glow of an electric heating element and feel the heat. At longer wavelengths, ambient temperature
becomes background noise, disturbing signals. And there are significant water bands in the infrared.
Plastic optical fiber (POF) is made from materials that have lower absorption at shorter wavelengths,
so red light at 650 nm is commonly used with POF, but at 850 nm attenuation is still acceptable so
short wavelength glass fiber transmitters may be used.
The three prime wavelengths for fiber optics, 850, 1300 and 1550 nm drive everything we design or
test. NIST (the US National Institute of Standards and Technology) provides power meter calibration
at these three wavelengths for fiber optics. Multimode fiber is designed to operate at 850 and 1300
nm, while singlemode fiber is optimized for 1310 and 1550 nm. The difference between 1300 nm and
1310 nm is simply a matter of convention, harking back to the days when AT&T dictated most fiber
optic jargon. Lasers at 1310 nm and LEDs at 1300 nm were used in singlemode and multimode fiber
respectively.

Plastic Optical
Fiber (POF)

Multimode
Graded Index
Fiber

Singlemode Fiber

650 nm
850 nm

850 nm
1300 nm

1310 nm
1490 - 1625 nm

OPTICAL WAVELENGTHS AND SPECTRUM
Band
O- band
E- band
S- band
C- band
L- band
U- band

Wavelength range
1260 nm- 1360 nm
1360 nm- 1460 nm
1460nm- 1530 nm
1530 nm- 1565 nm
1565 nm- 1625 nm
1625 nm – 1675 nm

Description
Original band
Extended band
Short wavelength band
Conventional band
Long wavelength band
Ultra long wavelength band

.

14

CONSTRUCTION
An optical fiber consists of a light carrying core surrounded by a cladding that traps the light in the core
by the principle of TOTAL INTERNAL REFLECTION.

DIAGRAM

Core:
The core of a conventional optical fiber is a cylinder of glass or plastic that runs along the fiber's
length. The core is surrounded by a medium with a lower index of refraction, typically a cladding of a
different glass, or plastic. Light travelling in the core reflects from the core-cladding boundary due to
total internal reflection, as long as the angle between the light and the boundary is less than the critical
angle. As a result, the fiber transmits all rays that enter the fiber with a sufficiently small angle to the
fiber's axis. The limiting angle is called the acceptance angle, and the rays that are confined by the
core/cladding boundary are called guided rays.
The core is characterized by its diameter or cross-sectional area. In most cases the core's cross-section
should be circular, but the diameter is more rigorously defined as the average of the diameters of the
smallest circle that can be circumscribed about the core-cladding boundary, and the largest circle that
can be inscribed within the core-cladding boundary.

15

Cladding:
Cladding is one or more layers of material of lower refractive index, in intimate contact with a core
material of higher refractive index. The cladding causes light to be confined to the core of the fiber by
total internal reflection at the boundary between the two.[1] Light propagation in the cladding is
suppressed in typical fiber. Some fibers can support cladding modes in which light propagates in the
cladding as well as the core. (From Federal Standard 1037C and from MIL-STD-188)
The numerical aperture of a fiber is a function of the indices of refraction of the cladding and the core
by:

Buffer coating:
In a fiber optic cable, a buffer is one type of component used to encapsulate one or more optical fibers
for the purpose of providing such functions as mechanical isolation, protection from physical damage
and fiber identification.
The buffer may take the form of a miniature conduit, contained within the cable and called a "loose
buffer", or "loose buffer tube". A loose buffer may contain more than one fiber, and sometimes
contains a lubricating gel. A "tight buffer" consists of a polymer coating in intimate contact with the
primary coating applied to the fiber during manufacture.
Buffer application methods include spraying, dipping, extrusion and electrostatic methods. Materials
used to create buffers can include fluoropolymers such as polyvinylidene fluoride (Kynar),
polytetrafluoroethylene (Teflon), or polyurethane.

16

TYPES OF OPTICAL FIBRES

OPTICAL FIBERS

SINGLEMODE
FIBERS

MULTIMODE
FIBERS

STEP INDEX

GRADED INDEX

OM1/OM2/OM3

STEP INDEX

SINGLEMODE FIBERS:
Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3
to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter,
through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than
multimode fiber, but requires a light source with a narrow spectral width.

Figure: Single Mode Step Index Fiber

17

MULTIMODE FIBRES:
Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron
range for the light carry component (in the US the most common size is 62.5um). Most applications in
which Multi-mode fiber is used, 2 fibers are used (WDM is not normally used on multi-mode fiber).
Step Index Multimode Fiber
This diagram corresponds to multimode propagation with a refractive index profile that is called step
index. The diameter of the core is fairly large relative to the cladding. There is also a sharp discontinuity
in the index of refraction as you go from core to cladding. As a result, when light enters the fiber-optic
cable on the left, it propagates down toward the right in multiple rays or multiple modes. This yields the
designation multimode. As indicated, the lowest-order mode travels straight down the center. It travels
along the cylindrical axis of the core.

Figure: Multimode Step Index

18

Graded Index Multimode Fiber
Multimode graded index fiber has a higher refractive index in the core that gradually reduces as it extends
from the cylindrical axis outward. Here the variation of the index of refraction is gradual as it extends out
from the axis of the core through the core to the cladding. There is no sharp discontinuity in the indices
ofrefraction between core and cladding. The core here is much larger than in the single-mode step index.

Figure: Graded Index Multimode Fiber
Multi-mode fibers are described by their core and cladding diameters. The transition between the core
and cladding can be sharp, which is called a step index profile, or a gradual transition, which is called
a graded index profile. The two types have different dispersion characteristics and thus different
effective propagation distance.
In addition, multi-mode fibers are described using a system of classification determined by the ISO
11801 standard — OM1, OM2, and OM3 — which is based on the modal bandwidth of the multimode fiber.
For many years 62.5/125 µm (OM1) and conventional 50/125 µm multi-mode fiber (OM2) were
widely deployed in premises applications. These fibers easily support applications ranging from
Ethernet (10 Mbit/s) to Gigabit Ethernet (1 Gbit/s) and, because of their relatively large core size,
were ideal for use with LED transmitters. Newer deployments often use laser-optimized 50/125 µm
multi-mode fiber (OM3). Fibers that meet this designation provide sufficient bandwidth to support 10
Gigabit Ethernet up to 300 meters. Optical fiber manufacturers have greatly refined their
manufacturing process since that standard was issued and cables can be made that support 10 Gbit up
to 550 meters. Laser optimized multi-mode fiber (LOMMF) is designed for use with 850 nm VCSELs.
The migration to LOMMF/OM3 has occurred as users upgrade to higher speed networks. LEDs have a
maximum modulation rate of 622 Mbit/s because they can not be turned on/off fast enough to support
higher bandwidth applications. VCSELs are capable of modulation over 10 Gbit/s and are used in
many high speed networks.
OM4 (defined in TIA-492-AAAD) was finalized in August 2009,] and was published by the end of
2009 by the TIA. OM4 cable will support 125m links at 40 and 100 Gbit/s.
Cables can sometimes be distinguished by jacket color: for 62.5/125 µm (OM1) and 50/125 µm
(OM2), orange jackets are recommended, while Aqua is recommended for 50/125 µm "laser
optimized" OM3 and OM4 fiber.

19

ADVANTAGES OF OPTICAL FIBRES
Wide bandwidth- Optical carriers are superior to radio frequency and microwave carriers due to
their high frequencies. Amount of data flow achieved through copper wires is limited. The very
high frequency of operation in an optical fiber leads to very high rates of data transmission.
Light weight and small size-Due to their small volume and lower density, optical fiber cables
enjoy considerable weight advantages over typical copper coaxial cables.
Immunity to electromagnetic interference-Since optical fibers are non conducting, they will
neither generate nor receive electromagnetic interference. This feature allows the use of fibers in
regions of high electric field.
Lack of EMI cross talk between channels-Electromagnetic interference called cross talk occurs
when two or more conducting lines lie near enough to each other to allow the signal from one to
leak into the other because of electromagnetic fields. However, the electromagnetic fields
extending from an optical fiber are negligible; hence there is no cross talk in an optical fiber.
Lack of sparking-For special purpose applications that require transmission on information
through hazardous cargo areas, fibers offer the potential advantage of not sparking, if there is a
break in the transmission line.
Compatibility with solid state sources- The physical dimensions of the fiber optic sources,
detectors and connectors and the fiber itself are compatible with modern miniaturized electronics.
Low cost-Copper is a critical commodity in the market and is hence, subjected to fluctuations in
the prices. The primary ingredient of silica based fiber is widely available and is not a critical
commodity. Not only does optical fiber offer enormous bandwidth, but it takes a lot less room.
Any one of these copper bundles can be replaced with one fiber strand.
No Emission Licenses-Fiber optics is a non- radiating means of information transfer and hence,
no government license is required to use the optical spectrum.

DISADVANTAGES OF OPTICAL FIBRES
High investment cost.
Need for more expensive optical transmitters and receivers.
More difficult and expensive to splicethan wires.
At higher optical powers, is susceptible to "fiber fuse" wherein a bit too much light meeting with
an imperfection can destroy as much as 1.5 kilometers of wire at several meters per second. A
"Fiber fuse" protection device at the transmitter can break the circuit to prevent damage, if the
extreme conditions for this are deemed possible.
Cannot carry electrical power to operate terminal devices. However, current telecommunication
trends greatly reduce this concern: availability of cell phones and wireless PDAs; the routine
inclusion of back-up batteries in communication devices; lack of real interest in hybrid metalfiber cables; and increased use of fiber-based intermediate systems.

20

APPLICATIONS OF OPTICAL FIBRES
The use and demand for optical fiber has grown tremendously and optical-fiber applications are
numerous.
Telecommunication applications are widespread, ranging from global networks to desktop
computers. These involve the transmission of voice, data, or video over distances of less than a
meter to hundreds of kilometers, using one of a few standard fiber designs in one of several cable
designs.
Carriers use optical fiber to carry plain old telephone service (POTS) across their nationwide
networks. Local exchange carriers (LECs) use fiber to carry this same service between central
office switches at local levels, and sometimes as far as the neighborhood or individual home
(fiber to the home [FTTH]).
Optical fiber is also used extensively for transmission of data. Multinational firms need secureand
reliable systems to transfer data and financial information between buildings to the desktop
terminals or computers and to transfer data around the world.
Cable television companies also use fiber for delivery of digital video and data services. The high
bandwidth provided by fiber makes it the perfect choice for transmitting broadband signals, such
as high-definition television (HDTV) telecasts.
Intelligent transportation systems, such as smart highways with intelligent traffic lights,
automated tollbooths, and changeable message signs, also use fiber-optic-based telemetry
systems.
Another important application for optical fiber is the biomedical industry. Fiber-optic systems are
used in most modern telemedicine devices for transmission of digital diagnostic images. Other
applications for optical fiber include space, military, automotive, and the industrial sector.

21

ITU-T STANDARDS

Worldwide, technologies for broadband access networks are advancing rapidly. Among these, the
technology applying single mode fiber provides for a high-capacity transmission medium which can
answer the growing demand for broadband services. The experience with the installation and operation of
single mode fiber and cable based networks is huge, and ITU-T Recommendation G.652 describing its
characteristics has been adapted to this experience. Nevertheless, the specific use in an optical access
network puts different demands on the fiber and cable which impacts its optimal performance
characteristics. Differences with respect to the use in the general transport network are mainly due to the
high density network of distribution and drop-cables in the access network. The limited space and the
many manipulations ask for operator friendly fiber performance and low bending sensitivity. In addition,
the cabling in the crowded telecom offices where space is a limiting factor has to be improved
accordingly.

TYPESOFITU-TSTANDARDS

There are mainly three types of ITU-T Standards. These are discussed as follows:

ITU-T
G.652

ITU-T
G.657

ITU-T
G.655

22

ITU-T G652
Series G: Transmission Systems and Media, Digital Systems and Networks Transmission media
characteristics.

Recommendations ITU-T G652 describes the geometrical, mechanical and transmission attributes of a
single-mode optical fiber and cable which has zero-dispersion wavelength around 1310 nm. This fiber
was originally optimized for use in the 1310-nm wavelength region, but also be used at1490 and 1550 nm
as well as other wavelengths. The first G.652 specification was created in 1984 with many revisions
since.

WAVELENGTH RANGE:1310 nm to 1550 nm

The standards include the following:
Mode field diameter (MFD)
Cladding diameter
Core-concentricity error
Non-circulatory
Cut-off wavelengths
Macrobending losses
Material properties of coefficient
Refractive index profile
Longitudinal uniformity of chromatic dispersion
Chromatic dispersion coefficient

TYPES
NAME

WAVELENGHTH RANGE

ITU-T G.652B
ITU-T G.652D

1360 nm to 1550 nm

BIT RATE
APPLICATIONS
Supports up to STM-64
(OC-192)
Supports up to STM-64
(OC-192)

23

ITU-T G657
The recommendation describes two categories of single mode optical fiber cable suitable for use in the
access network, inside buildings at the end of those networks. The G.657 recommendation was created to
support this optimization by recommending much improved bending performance compared with existing
G.652 single mode fibers and cables. This is done by introducing two classes of single mode fibers, one
of which, class a, is fully compliant with the G.652 single mode fibers and can also be used in other parts
of the network.It is suitable for use in O, E, S, C and L bands.

WAVELENGTH RANGE:1260nm to 1625nm

Cladding diameter
Non-circulatory
Cut-off wavelengths
Macro bending losses

TYPES
NAME

WAVELENGTH

SPECIFICATIONS

1550 nm
1625 nm

Minimum bend radius of 10mm
Minimum design radius of 7.5mm
Minimum bend radius of 7.5mm
Minimum design radius of 5mm

G.657A1
G.657A2

G.657B2
G.657B3

24

ITU-T G655
Recommendation of ITU-T G655 describes the geometrical , mechanical and transmission attributes of a
single mode optical fiber which has a absolute value of chromatic dispersion coefficient greater than zero
throughout the wavelength range .This dispersion reduces the growth of non-linear effects ,which are
particularly deleterious in dense wavelength division multiplexing systems(DWDM).

WAVELENGTH RANGE: 1530 nm to 1565 nm

Cladding diameter
Non-circulatory
Cut-off wavelengths
Macro bending losses

TYPES
NAME
ITU-T G.655A

ITU-T G.655B

SPECIFICATION
Maximum launch power could be restricted
Typical minimum channel spacing could
be restricted to 200 GHz
Maximum launch power could be higher
than G.655A
Typical minimum channel spacing could
be restricted to 100 GHz or less

25

CONNECTORS
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 that light
can pass. Better connectors lose very little light due to reflection or misalignment of the fibers. Optical
fiber connectors are used to join optical fibers where a connect/disconnect capability is required. The
basic connector unit is a connector assembly. A connector assembly consists of an adapter and two
connector plugs. Due to the polishing and tuning procedures that may be incorporated into optical
connector manufacturing, connectors are generally assembled onto optical fiber in a supplier’s
manufacturing facility.
Outside plant applications may involve locating connectors underground in subsurface enclosures that
may be subject to flooding, on outdoor walls, or on utility poles. The closures that enclose them may be
hermetic, or may be free-breathing. Hermetic closures will subject the connectors within to temperature
swings but not to humidity variations unless they are breached. Free-breathing closures will subject them
to temperature and humidity swings, and possibly to condensation and biological action from airborne
bacteria, insects, etc. Connectors in the underground plant may be subjected to groundwater immersion if
the closures containing them are breached or improperly assembled.
Features of a good connector design:
Low Insertion Loss
Low Return Loss
Ease of installation
Low cost
Reliability
Low environmental sensitivity
Ease of use

FERRULES
Ferrule is the most important component of fiber optic connectors. It could be made of different materials,
such as plastics, stainless steel, and ceramics. Most of the ferrules used in optical connectors are made of
ceramic material due to some of the desirable properties they possess. These include low insertion loss
required for optical transmission, remarkable strength, small elasticity coefficient, easy control of product
characteristics, and strong resistance to changes in environmental conditions.
The production process is an extremely complex one, which begins with injecting zirconium-dioxide
powder into pre-designed molds. The work-in-process is degreased, burned, reduced and ground, and then
to become finished ceramic ferrules. Figure of a ferrule is given below:

26

TYPES OF CONNECTORS
Many types of optical connector have been developed at different times, and for different purposes. Many
of them are summarized in the table below:
Short name

Long form

Coupling
type
Snap

SC

Subscriber
Connector

FC

Ferrule
connector

Screw

LC

Lucent
connector

Snap

ST

Straight Tip

Ferrule
diameter
2.5 mm
2.5 mm

Standard
IEC 61754-4

Datacom and telecom;
GBIC; extremely common

IEC 6175413

Datacom, telecom,
measurement equipment,
single-mode lasers;
High-density connections,
SFP transceivers, XFP
transceivers
Multimode, rarely singlemode; APC not possible
(note 3)
Telecom, DWDM systems;

1.25 mm

IEC 6175420

Bayonet

2.5 mm

IEC 61754-2

E-2000

Snap, with
light and
dust-cap

2.5 mm

IEC 6175415

BICONICAL

Screw
Snap
(multiplex
push-pull
coupling)

2.5 mm

MPO

MultipleFiber
PushOn/Pulloff

MTRJ

Mechanical
Transfer
Registered
Jack

FSMA

Snap
(duplex)

Screw

Typical applications

Obsolete

2.5×6.4 mm

IEC-617547; EIA/TIA604-5
(FOCIS 5)

2.45×4.4 mm

IEC 6175418

3.175 mm

IEC 60874-2

SM or MM multi-fiber
ribbon. Same ferrule as
MT, but more easily
reconnect able. Used for
indoor cabling and device
interconnections. MTP is a
brand name for an
improved connector, which
intermates with MPO.
Duplex multimode
connections

Datacom, telecom, test and
measurement

27

E2000CONNECTOR
Features:
The ferrule is protected by the integrated spring loaded shutter.
The connector housing protects the ferrule all round against dust, dirt and
scratches.
Latched push – pull locking type..
Fiber cable assemblies result in super performance on insertion loss as well as exceptional
repeatability.
Full ceramic ferrule.
Adjustable in 60˚ steps.
Excellent for high packing density.
Specifications:
E2000 connector Specifications
Single mode

Multimode

<0.20dB

<0.25dB

Insertion Loss
Return Loss

>55 dB (PC) >65 dB (APC)

Durability

<0.20 dB typical change, 1000 matings

SC CONNECTOR
SC optical fiber connector is comprised of a polymer body and aceramic ferrule plus a crimp over sleeve
and rubber boot. These connectors are suitable for, 900μm and 2 and 3mm cables.
Features:
Threaded, key oriented coupling mechanism which allows repeatable, low

loss connections.
Simplex or duplex and multi fiber assemblies are available in both standard
and custom configurations.
Specifications:
SC connector Specifications
Single mode
Insertion Loss
Return Loss
Durability

Multimode

<0.20dB

<0.20dB

>55dB

>45dB
1000 mate/ demate cycles

28

FC CONNECTOR
Both singlemode and multimode configurations come with a zirconia ceramic
ferrule with pre- polished FC profile and convex spherical end. These end face
types allow faster polishing, low back reflection and optical los, while ensuring
maximum repeatability.
Features:
Precision mechanical dimension.
Ultra low back reflection.
Corrosion resistant body.
For 3.0mm, 2.0mm jacket or 900 m buffer.
Compatible with APC hardware.
Free-floating APC ceramic ferrule.
Specifications:
FC connector Specifications
Single mode

Multimode

<0.20dB

<0.20dB

>55dB

>45dB

Insertion Loss
Return Loss
Durability


ST CONNECTOR
ST stands for Straight Tip connectors. They are used for both short distance and long
line systems. It has a bayonet mount and a long cylindrical ferrule to hold the fiber.
Because they are spring loaded, they have to be seated properly.
Features:
Twist lock bayonet coupling mechanism which ensures quick, highly
repeatable, low loss connections.
Standard crimp kevlar retention.
Specifications:
ST connector Specifications
Single mode
Insertion Loss
Return Loss
Durability

Multimode

<0.20dB

<0.20dB

>55dB

>45dB

29

LC CONNECTORS
The LC Connector family was designed to provide a high performance
SFFC incorporating traditional technology, advances in latching systems,
and versatile for both singlemode and multimode fiber applications.
Features:
Available in 2mm patch, 3mmpatch and 900 μm.
Termination Procedures: Prep cable end, Epoxy-Crimp-Polish.
Connector versions available for: 2mm Cable, 900 μm Buffered Fiber, Simplex & Duplex.
Available in Blue (single mode), Beige (multimode).
Specifications:
LC connector Specifications
Single mode
Insertion Loss
Return Loss

Multimode

<0.20dB

<0.20dB

>50dB

>45dB

Durability


MT- RJ CONNECTORS
MT-RJ Connector uses a RJ-latching mechanism familiar to installers. Also, the MT-RJ is a small formfactor connector package that doubles the densitycompared to standard SC connectors.
Features:
Precision molded MT ferrule.
High precision guide pins for exact alignment.
Duplex ferrule.
Plug jack (RJ - 45) design.
Specifications:
MT-RJ connector Specifications
Single mode
Insertion Loss
Return Loss
Durability

Multimode

<0.20dB

<0.25dB

>45dB

30

MPO CONNECTORS
They are very high density, small form factor fiber optic connectors
developed by NTT around the MT ferrule, to simply the process of pretermination.
Features:
No of Standard MT interface connects: 4, 8, and 12 singlemode or multimode fiber.
Precision guide pins provide high-precision alignment for high-optical performance.
Integral no-epoxy strain relief.
Specifications:
MPO connector Specifications
Single mode

Multimode

<0.35db – premium
<1.00dB- maximum

<0.75dB

>60dB

>35dB

200 mate/demate cycles

200 mate/demate cycles

Insertion Loss
Return Loss
Durability

BICONIC CONNECTORS
Biconic connector is still in use today; mostly for military applications. Biconic connector utilizes a screw
type, spring loaded connection and features a cone-shaped polymer
ferrule that helps to align the optical fibers at the connection interface. It
provides top performance for singlemode and multimode applications.
Features:
Precision molded polymer.
Conical thermoplastic ferrule.
Singlemode / Multimode.
Easy termination.
Specifications:
Specifications

Singlemode/ Multimode

Insertion loss

≤ 0.50dB typical

Material -

Body Precision molded

31

FSMA CONNECTORS
SMA (Sub-Miniature Version-A)connectorsare coaxial RF connectors developed in the 1960s as a
minimal connector interface for coaxial cable with a screw type coupling mechanism. The connector has a
50Ωimpedance. It offers excellent electrical performance from DC to 17 GHz.
Features:
Threaded nut connector.
One piece construction.
Simple termination.
Single crimp design.
Non- contact connector.
Specifications:
128μm & 144μm SMA ferrule
(zirconia, 905 series):

< 0.8dB typical

Insertion loss
128μm & 144μm stainless steel
ferrule:
< 2.0dB typical

< 2.0dB typical

FDDI CONNECTORS
Features:
Installation in push and pull style.
Compatible with all FDDI-compliant connectors and active equipment.
Low insertion loss.
Clear indication of proper keying to end-users by connector labels.
Various brand name connectors are available upon request.
Specifications:
Parameter
Insertion loss
Back reflection
Durability
Operating Temperature

Singlemode
0.3Db
30Db
-40°C to +80°C

32

POLISHING
Fiber optic connectors can have several different ferrule shapes or finishes, usually referred to as polishes.
Early connectors, because they did not have the keyed ferrules and could not rotate in mating adapters,
always had an air gap between the connectors to prevent them from rotating and grinding scratches into
the ends of the fibers. Beginning with the ST and FC, which had keyed ferrules, the connectors were
designed to contact tightly, what we now call physical contact (PC) connectors.

The end of the connector ferrule provides the optical contact between two fibers. We usually polish the
ends to minimize the losses.

33

TYPES OF POLISHING
The amount of insertion loss is affected by fiber alignment, and/or the quality of the finishing on the end
of ferrule, while return loss is affected by the style of polishing on the ceramic ferrule in a connector.
There are three different styles of polishing, reflected by their shape of the finish:

1. Physical Contact (PC)
In the PC style, the fiber is polished to a smooth curve. As the name implies (i.e. physical
contact), the ferrules of adjoining fibers come into physical contact. This reduces the air
gap between the contacting ferrules, resulting in lower insertion losses. The smooth curve
in the PC style is designed to reduce the return loss by reflecting the light out of the fiber.

2. Ultra Physical Contact (UPC)
The UPC style ferrule has the shape of the PC style. They are polished with several
grades of polishing film that allows for an ultra smooth surface. The main difference
between UPC and PC is that the former have a lower return loss.

3. Angled Physical Contact (APC)
The APC style produces the lowest return loss when compared to other styles. The ferrule
is finished to anangle of typically 8 degrees. The angle is calculated so that it is less than
the critical angle, which implies that light is not propagated back along the fiber.

34

ADAPTERS
Fiber optic adapter are used in fiber optic connection, the typical use is to provide a cable to cable fiber
connection. People sometimes also name them to be mating sleeves and hybrid adaptors, mating sleeves
means this fiber optic adapter is used to connect the same type fiber optic connectors, while hybrid
adaptors are the fiber optic adaptor types used to connect different kinds of fiber optic connectors.

SC ADAPTER
Typical SC fiber optic adapters are with plastic housing and for single mode SC UPC it is blue color,
single mode SC APC it is green color, multimode SC UPC is beige color. Most of these adapters come
with ceramic sleeves, while there are bronze sleeve SC adapters which are generally multimode types.
SC Fiber optic adapter features:
Compact design.
High precision alignment.
Low insertion and return loss and back reflection.
Choice of metal or plastic housing, mount styles & flange options.
SC Fiber optic adapter applications:
CATV
Telecommunication networks
Local Area Networks (LANs)
Data processing networks
Industrial, military and medical

ST ADAPTERS
The ST fiber optic adapters include the single mode and multimode types. These ST fiber adapters are
simplex style, most are with zirconia sleeves, and optional bronze sleeve adapters are available for
multimode.
ST fiber optic adapter features:
Compact design
High precision alignment
Low insertion and return loss and back reflection
Choice of metal or plastic housing, phosphor bronze or zirconia split sleeves
ST fiber optic adapter applications:
Premise installations
Instrumentation

35

MT – RJ ADAPTER
MT-RJ fiber adapters are with polymer housing, with flange type adapters and SC
footprint types available.
MTRJ fiber optic adapter features:
Plug-jack (RJ-45) design
TIA/EIA 568-A Compliant
MTRJ fiber optic adapter applications:
Gigabit Ethernet, Asynchronous Transmission Method
(ATM)
CATV
Active Device/Transceiver Interface
Premise Installations
Telecommunication Networks
Multimedia
Industrial and Military

LC ADAPTER
LC adapters are single mode and multimode styles with
plastic housing and zirconia sleeve, with optional bronze
sleeve adapters for multimode. There are stand LC fiber
adapter and SC footprint LC fiber optic adapters available.

LC fiber optic adapter features:
Compact design
Color coding & polarization
Low insertion and return loss and back reflection
LC fiber optic adapter applications:
Video
CATV
Active device/Transceiver interface
Premise installations
Multimedia
Gigabit Ethernet

36

FC ADAPTERS
FC fiber optic adapters, including square type, single
D type and double D types, in single mode and
multimode versions. All these adapters are with metal
housing and ceramic sleeves. The FC square fiber
optic adapter is available in the standard body styles
with nickel plated brass or nickel plated zinc housing
and arecorrosion resistance.

FC fiber optic adapter features:
Compact design
Low insertion and return loss and back reflection*

FC fiber optic adapter applications:
CATV
Local Area Networks (LANs)
Metro networks
Data processing networks

E2000 ADAPTER
E2000 fiber adapters are with zirconia sleeves and in
simplex style. E2000 is a trademark of Diamond
company.
E2000 fiber optic adapter features:
Secure transmission of high bit-rate protocols
Compliant with European (EN 186270) and International (IEC 61754-15)
standards
Tested and approved by Swisscom
E2000 fiber optic adapter applications:
WANs, LANs, CATV
Metrology, Railway, Industry

37

FSMA ADAPTER
Features:
High precision
Easy installation
Low insertion loss
Good exchangeability and repeatability
Zirconia and phosphor-bronze sleeve
Applications:
Telecommunication
Computer network
CATV networks
Instrumentation
Active device termination

MPO ADAPTERS

Specifications:
Compact design, accommodating 4, 8 or 12 fiber ribbons
Low insertionand return loss and back reflection.

Applications:
Equipment Interconnections
Telecommunications networks
Broadband/CATV networks
Data communications networks, including high-bandwidth equipment
Interconnections for parallel optical transmitters and receivers

38

FDDI ADAPTERS
Features:
Dual-(DAS) or Single-(SAS) Attachment Station options available
Optical Bypass Switch Control
Fully software configurable
Applications:
SAFENET applications
Distributed real-time applications
Vetronics applications
Mission-critical applications
SCADA applications

39

ATTENUATORS
Fiber optic attenuator is used in the fiber optic communications to reduce the optical fiber power at a
certain level, the most commonly used type is female to male plug type fiber optic attenuator, it has the
optical fiber connector at one side and the other side is a female type fiber optic adapter, fiber optic
attenuator name is based on the connector type and the attenuation level. SC 5dB fiber optic attenuator
means this attenuator use SC fiber optic connector and it can reduce the optical fiber power level by 5dB.
Commonly used attenuation range is from 1dB to 20dB.
Adjustable fiber optic attenuator, also called variable fiber optic attenuator , usually is inline type, the
appearance like fiber optic patch cord; it is with an adjustable component in the middle of the device to
change the attenuation level to a certain figure. There are also handheld variable fiber optic attenuators;
they are used as test equipment, and we have the inline fiber optic attenuators .

SCATTENUATORS
Features:
They fit typical 1310nm and 1550nm single mode fiber
applications.
Attenuation range is from 1dB to 30dB.
The SC fiber attenuators are with SC connector interface. They
are with premium ceramic sleeves.
Plug type SC fiber attenuator is a female to male type.
Bulkhead SC fiber attenuator is a female to female type.
Operation wavelength range is 1240nm to 1620nm.
They are used inline to decrease the optical power light in the systems for both lab and commercial
applications.
The SC fiber optic attenuators are very good performance and fairly good price.

LCATTENUATORS
Features:
They are with high quality ceramic sleeves and UPC polishes.
Attenuation range available is from 1dB to 30dB.
Working range of the LC fiber attenuator is 1240nm to 1620nm,
including the typical 1310nm and 1550nm single mode applications.
They are constructed of the highest quality materials and every piece is
tested during production.
The LC fiber optic attenuator is used with fiber amplifier, DWDM and
telecommunications equipment.

40

FCATTENUATORS
Features:
Ceramic sleeves and accurate FC connection interface.
The attenuation range is from 1dB to 30dB available.
The FC fiber attenuator features high power endurance and low
back reflection.
Reduce the optical power in the fiber optic links.
Applications include CATV networks, data communication and telecommunication networks.

STATTENUATORS
Features:
They are with 1240nm to 1620nm compatible working wavelength,
including the 1310nm and 1550nm typical single mode wavelength.
Equipped with ceramic sleeves and features high quality and long
lifetime.
Attenuation range is from 1dB to 30dB.
The ST fiber attenuators are used inline to reduce the fiber optic power
by a certain fixed value.
They are high attenuation accuracy and working temperature from -40 C to +75 C.

E2000 ATTENUATORS
Features:
Low back reflection and Low PDL
High precision attenuation value
Precision control of attenuation range
Wide attenuation range
Precision ceramic ferrule
Plastic or metal housing material

41

MPO ATTENUATORS
Features:
Durability
Wavelength Independent
Simple and Reliable Structure
ROHS compliant

MT – RJ ATTENUATORS
Features:
Low back reflection and Low PDL
High precision attenuation value
Precision control of attenuation range
Wide attenuation range
Precision ceramic ferrule
Plastic or metal housing material
Low price

42

FTTH CABLES
Fiber optic "cable" refers to the complete assembly of fibers, strength members and jacket. Fiber optic
cables come in lots of different types, depending on the number of fibers and how and where it will be
installed. Choose cable carefully as the choice will affect how easy it is to install, splice or terminate and,
most important, what it will cost!
Choosing a Cable
Cable's job is to protect the fibers from the hazards encountered in an installation. Will the cables be
exposed to chemicals or have to withstand a wide temperature range? What about being gnawed on by a
woodchuck or prairie dog? Inside buildings, cables don't have to be so strong to protect the fibers, but
they have to meet all fire code provisions. Outside the building, it depends on whether the cable is buried
directly, pulled in conduit, strung aerially or whatever.
You should contact several cable manufacturers (two minimum, three preferred) and give them the specs.
They will want to know where the cable is going, how many fibers you need and what kind (singlemode
or multimode or both in what we call "hybrid" cables.) You can also have a "composite" cable that
includes copper conductors for signals or power. The cable companies will evaluate your requirements
and make suggestions. Then you can get competitive bids.
Since the plan will call for a certain number of fibers, consider adding spare fibers to the cable - fibers are
cheap! That way, you won't be in trouble if you break a fiber or two when splicing, breaking-out or
terminating fibers. And request the end user consider their future expansion needs. Most users install lots
more fibers than needed, especially adding singlemode fiber to multimode fiber cables for campus or
backbone applications.

Cable Design Criteria

Pulling Strength: Some cables are simply laid into cable trays or ditches, so pull strength is not too
important. But other cable may be pulled thorough 2 km or more of conduit. Even with lots of cable
lubricant, pulling tension can be high. Most cables get their strength from an aramid fiber (Kevlar is the
DuPont trade name), a unique polymer fiber that is very strong but does not stretch - so pulling on it will
not stress the other components in the cable. The simplest simplex cable has pull strength of 100-200
pounds, while outside plant cable may have a specification of over 800 pounds.
Water Protection: Outdoors, every cable must be protected from water or moisture. It starts with a
moisture resistant jacket, usually PE (polyethylene), and a filling of water-blocking material. The usual
way is to flood the cable with a water-blocking gel. It's effective but messy - requiring a gel remover. A
newer alternative is dry water blocking using a miracle powder - the stuff developed to absorb moisture in
disposable diapers.

45

Fire Code Ratings: Every cable installed indoors must meet fire codes. That means the jacket must be
rated for fire resistance, with ratings for general use, riser (a vertical cable feeds flames more than
horizontal) and plenum (for installation in air-handling areas. Most indoor cables us PVC (polyvinyl
chloride) jacketing for fire retardance. In the United States, all premises cables must carry identification
and flammability ratings per the NEC (National Electrical Code) paragraph 770. These ratings are:

NEC Rating

Description

OFN

Optical fiber non-conductive

OFC

Optical fiber conductive

OFNG or OFCG

General purpose

OFNR or OFCR

Riser rated cable for vertical runs

OFNP or OFCP

Plenum rated cables for use in air-handling plenums

OFN-LS

Low smoke density

46

SIMPLEX FLAT INDOOR CABLE USED UNDER CARPET
Features:
Good mechanical and environmental characteristics.
Flame retardant characteristics meet the requirements of relevant
standards.
The mechanical characteristics meet the requirements of relevant
standards.
Soft, flexible, easy to splice.
Big capacity for data transmission.
Meets various requirements of market and clients.
Application:
Used in indoor cabling, especially used under carpet.
Specifications:
Fiber Cable
Cable
count dimension weight
Mm
1

2.5 x 4.5

kg/km
15.5

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
80

Long
term
100

Short
term
500

Short
term
150

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

50

30

-20 to +60

°C

DUPLEX FLAT INDOOR CABLE I
Features:
Good mechanical and environmental
characteristics.
Flame retardant characteristics meet the
requirements of relevant standards.
The mechanical characteristics meet the
requirements of the relevant standards.
Meet various requirements of market and clients.
Applications:
Used as pigtails and patch cords.
Used in optical connections in optical communication rooms, optical distribution frames, optical
apparatus and equipments.
Used in indoor cabling.

47

Specifications:
Fiber Cable
Cable
Mm
2
2
2
2
2
2

1.6 x 3.4
1.8 x 3.8
2.0 x 4.2
2.4 x 5.0
2.8 x 5.8
3.0 x 6.2

kg/km
4.0
5.0
6.0
9.0
10.4
11.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
60
80
100
100
160
160

Long
term
200
200
200
200

Short
term
1000
1000
1000
1000

Short
term
120
160
200
200
300
300

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

50
50
50
50
60
60

30
30
30
30
30
30

-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60

°C

DUPLEX FLAT INDOOR CABLE III
Features:
characteristics.
Applications:
Used in indoor cabling, especially in poor laying conditions.
Used in optical connections in optical communication equipment rooms and optical distribution
frames.
Specifications:
Fiber Cable
Cable
Mm
2
2
2

2.6 x 4.8
3.0 x 5.0
4.0 x 7.0

kg/km
9.4
11.3
18.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100
100
160

Long
term
200
200
200

Short
term
1500
1500
1500

Short
term
200
200
300

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

100
100
100

35
40
40

-20 to +60
-20 to +60
-20 to +60

°C

48

DUPLEX FLAT INDOOR CABLE IV
Features:
Flame retardant characteristics meet the requirements of
relevant standards.
The mechanical characteristics meet the requirements of
the relevant standards.
Applications:
frames.
Specifications:
Fiber Cable
Cable
Mm
2
2

3.8 x 6.7
3.8 x 7.5

kg/km
24.0
29.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
160
160

Long
term
200
200

Short
term
1500
1500

Short
term
300
300

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

100
100

40
40

-20 to +60
-20 to +60

°C

DUPLEX ROUND INDOOR CABLE I
Features:
Meet various requirements of market and
clients.

49

Applications:
frames.
Used in optical connections in optical apparatus and equipments.
Specifications:
Fiber Cable
Cable
Mm
2
2

3.2
3.8

kg/km
8.1
10.9

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100
100

Long
term
200
200

Short
term
1000
1000

Short
term
200
200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

100
100

40
40

-20 to +60
-20 to +60

°C

DUPLEX ROUND INDOOR CABLE II
Features:
characteristics.
Meet various requirements of market and
clients.
Applications:
frames.

50

Specifications:
Fiber Cable
Cable
Mm
2
2

6.0
7.2

kg/km
25.3
30.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
200
250

Long
term
200
200

Short
term
1000
1000

Short
term
400
500

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D
20D

10D
10D

-20 to +60
-20 to +60

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

50

30

-20 to +60

°C

DUPLEX FLAT INDOOR CABLE USED UNDER CARPET I
Features:
Good mechanical and
environmental characteristics.
Flame retardant characteristics
meet the requirements of relevant
standards.
The mechanical characteristics
meet the requirements of the
relevant standards.
Applications:
Specifications:
Fiber Cable
Cable
Mm
2

2.2 x 16.0

kg/km
27.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100

Long
term
300

Short
term
1500

Short
term
200

°C

51

DUPLEX FLAT INDOOR CABLE USED UNDER CARPET II
Features:
Applications:
Specifications:
Fiber Cable
Cable
Mm
2

2.0 x 5.0

kg/km
15.0

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100

Long
term
200

Short
term
1000

Short
term
200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

50

30

-20 to +60

°C

DUPLEX FLAT LOOSE TUBE INDOOR CABLE
Features:
characteristics.
Applications:
Used as access building cables.
Used in optical connection with higher fiber transmission requirement in optical communication
equipment.

52

Specifications:
Fiber Cable
Cable
Mm
2

3.8 x 6.8

kg/km
25.9

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
160

Long
term
200

Short
term
1000

Short
term
300

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

100

40

-20 to +60

°C

DUPLEX ROUND LOOSE TUBE INDOOR CABLE I
Features:
characteristics.
Applications:
Used in indoor cabling, the cable bend radius should not be too small.
Used in optical connection with higher fiber transmission requirement in optical communication
equipment.
Used as access building cables.
Specifications:
Fiber Cable
Cable
Mm
2

3.3

kg/km
10.5

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100

Long
term
200

Short
term
1000

Short
term
200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

100

35

-20 to +60

°C

53

4 – FIBER PARALLEL INDOOR CABLE
Features:
characteristics.
The mechanical characteristics of jacket
meet the requirements of relevant standards.
Flexible, easy to lay and splice.
Applications:
Used as access building cable.
Used as interconnect lines of equipments and used in optical connections in optical
communication rooms and optical distribution frames.
Specifications:
Fiber Cable
Cable
Mm
2

8.4 x 2.0

kg/km
13.2

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100

Long
term
200

Short
term
1000

Short
term
200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

50

30

-20 to +60

°C

MULTI – FIBER DISTRIBUTION INDOOR CABLE I
Features:
characteristics.
The mechanical characteristics of jacket meet
the requirements of relevant standards.

54

Applications:
Used in indoor cabling, especially used as distribution cable.
Used as interconnect lines of equipments, and used in optical connections in optical
communication equipment rooms and distribution frames.
Specifications:
Fiber Cable
Cable
Mm
4
6
8
12
16
24
48

5.0
5.2
5.5
6.5
7.5
8.0
12.5

kg/km
17
21
28
36
44
59
130

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
70
100
130
300
350
400
600

Long
term
200
200
200
200
200
200
200

Short
term
1000
1000
1000
1000
1000
1000
1000

Short
term
70
100
130
300
350
400
600

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D
20D
20D
20D
20D
20D
20D

10D
10D
10D
10D
10D
10D
10D

-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60

°C

COVERED WIRE CABLE I
Features:
characteristics.
standards.
Applications:
Used in indoor cabling, especially used for FTTH.

55

Specifications:
Fiber Cable
Cable
Mm
1 to 2

3.1 x 2.0

kg/km
8.2

Tensile Tensile
(N)
(N)

Crush

Crush

Long
Short
term
term
60/ 100
100/
200

Long
term
500/
1000

Short
term
1000/
2200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20H

10H

-20 to +60

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20H

10H

-20 to +60

°C

COVERED WIRE CABLE II
Features:
relevant standards.
The mechanical characteristics of jacket meet the requirements
of relevant standards.
Applications:
Specifications:
Fiber Cable
Cable
Mm
1 to 2

3.1 x 2.0

kg/km
8.2

Tensile Tensile
(N)
(N)

Crush

Crush

Long
Short
term
term
60/ 100
100/
200

Long
term
500/
1000

Short
term
1000/
2200

°C

56

COVERED WIRE CABLE III
Features:
characteristics.
standards.
Applications:
Specifications:
Fiber Cable
Cable
Mm
4

4.0 x 2.0

kg/km
8.2

Tensile Tensile
(N)
(N)

Crush

Crush

Long
Short
term
term
60/ 100
100/
200

Long
term
500/
1000

Short
term
1000/
2200

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20H

10H

-20 to +60

°C

SELF- SUPPORTING COVERED WIRE CABLE
Features:
Flame retardant characteristics meet the requirements
The mechanical characteristics of jacket meet the
Applications:
Used in access network or as access cable from outdoor to indoor in customer premises network.
Used as access building cable in premises distribution system, especially used in indoor or outdoor
aerial access cabling.

57

Specifications:
Fiber Cable
Cable
Mm
1 to 2

5.0 x 2.0

kg/km
17.7

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
300

Long
term
1100

Short
term
2200

Short
term
600

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20H

10H

-20 to +60

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D

50D

-20 to +60

°C

ARMOUR COVERED WIRE CABLE
Features:
relevant standards.
Applications:
Mainly used in building aerial and duct access cabling.
Specifications:
Fiber Cable
Cable
Mm
1 to 2

6.8

kg/km
47

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
100

Long
term
500

Short
term
1000

Short
term
200

°C

58

LOOSE TUBE CABLE II
Features:
Applications:
Mainly used in building aerial and duct access cabling.
Specifications:
Fiber Cable
Cable
mm
2
4
6
8
12

kg/km

9.7
9.9
10.2
11.5
12.0

108
111
116
134
141

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
300
300
300
300
300

Long
term
300
300
300
300
300

Short
term
1000
1000
1000
1000
1000

Short
term
800
800
800
800
800

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D
20D
20D
20D
20D

10D
10D
10D
10D
10D

-20 to +60
-20 to +60
-20 to +60
-20 to +60
-20 to +60

°C

DUPLEX ROUND FAR TRANSMISSION CABLE III
Features:
Flame retardant characteristics meet the requirements
Applications:
Mainly used in wireless base station (BS) horizontal and vertical cabling.

59

Specifications:
Fiber Cable
Cable
Mm
2

7.0

kg/km
45

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
200

Long
term
1000

Short
term
2000

Short
term
400

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D

10D

-20 to +60

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D

10D

-20 to +60

°C

DUPLEX ROUND FAR TRANSMISSION CABLE IV
Features:
Applications:
Specifications:
Fiber Cable
Cable
mm
2

kg/km

5.5

28

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
200

Long
term
500

Short
term
1000

Short
term
400

°C

60

DUPLEX ROUND FAR TRANSMISSION CABLE V
Features:
relevant standards.
Applications:
Specifications:
Fiber Cable
Cable
mm
2

kg/km

5.0

22

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
200

Long
term
500

Short
term
1000

Short
term
400

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20D

10D

-20 to +60

°C

4- FIBER PARALLEL FAR TRANSMISSION CABLE
Features:
relevant standards.
Applications:
Used in indoor and outdoor cabling, especially used in wireless base station (BS).
Specifications:
Fiber Cable
Cable
mm
4

kg/km

16.0 x 9.0

102

Tensile Tensile
(N)
(N)

Crush

Crush

Long
term
400

Long
term
1100

Short
term
2200

Short
term
800

Min.
bend
radius
Dynamic

Min.
bend
radius
Static

Range of
temperature

20H

10H

-20 to +60

°C

61

LOSSES IN OPTICAL FIBERS

LOSSES

ATTENUATION

SCATTERING

ABSORPTION

DISPERSION

MODAL

DISPERSION

POLARISATION

ATTENUATION
Attenuation is the loss of optical energy as it travels through the fiber; thisloss is measured in dB/km.
Attenuation is a transmission loss that can be measured as a difference between the output signal powers
and the input signal power.
It can be expressed in dB as:
Attenuation loss α = 10 log10(P input/ Poutput) Db
The attenuation loss of fiber in dB/km is then expressed as:
α = 10 log10 (P input/ P output) / L dB/km
•
Attenuation is a measure of the loss of signal strength or light power that occurs as light pulses
propagate through a run of multimode or single-mode fiber.Attenuation in fiber optics, also known
as transmission loss, is the reduction in intensityof the light beam (or signal) with respect to distance
traveled through a transmissionmedium.
Causes of Attenuation:Empirical research has shown that attenuation in optical fiber is caused primarily
by bothscattering and absorption.

62

Significance of measuring attenuation:
Attenuation is an important consideration in the design of optical transmission links since it
determines the maximum repeater less transmission distance between Tx and Rx.
Attenuation depends on –
a) Attenuation depends on wavelength used (i.e. frequency used). The most common peak wavelengths
are 780 nm, 850 nm, 1310 nm, 1550 nm, and 1625 nm.
b) Attenuation depends on light intensity i.e. input light power
c) Attenuation depends on diameter of optical fiber (diameter of core mainly). For single/mono mode
attenuation is minimum since lesser the traversed distance lesser the power loss) Attenuation definitely
depends on distance. Distance between optical source andrepeater/detector.
Glass fiber (which has a low attenuation) is used for long-distancefiber optic cables; plastic fiber has a
higher attenuation and henceshorter range.

ABSORPTION
Absorption is a major cause of signal loss in an optical fiber. Absorption is defined as the portion of
attenuation resulting from the conversion of optical power into another energy form, such as heat.
Absorption in optical fibers is explained by three factors:
Imperfections in the atomic structure of the fiber material
The intrinsic or basic fiber-material properties
The extrinsic (presence of impurities) fiber-material properties
Imperfections in the atomic structure induce absorption by the presence of missing molecules or oxygen
defects. Absorption is also induced by the diffusion of hydrogen molecules into the glass fiber. Since
intrinsic and extrinsic material properties are the main cause of absorption, they are discussed further.

Intrinsic Absorption- Intrinsic absorption is caused by basic fiber-material properties. If an
optical fiber were absolutely pure, with no imperfections or impurities, then all absorption would
be intrinsic. Intrinsic absorption sets the minimal level of absorption. In fiber optics, silica (pure
glass) fibers are used predominately. Silica fibers are used because of their low intrinsic material
absorption at the wavelengths of operation.
In silica glass, the wavelengths of operation range from 700 nanometers (nm) to 1600 nm. Figure
2-21 shows the level of attenuation at the wavelengths of operation. This wavelength of
operation is between two intrinsic absorption regions. The first region is theultraviolet region
(below 400-nm wavelength). The second region is the infrared region (above 2000-nm
wavelength.
Intrinsic absorption in the ultraviolet region is caused by electronic absorption bands. Basically,
absorption occurs when a light particle (photon) interacts with an electron and excites it to a
higher energy level. The tail of the ultraviolet absorption band is shown in figure

63

Cause of Intrinsic Absorption:
Intrinsic absorption is due to material and electron absorption.
Material absorption -is a loss mechanism which results in the dissipation of someof the transmitted
optical power into heat in the optical fiber.An absolutely pure silicate glass has little intrinsic absorption
dueto its basic material structure.
Electron Absorption:Intrinsic absorption in the ultraviolet region is caused by electronic absorption.
Basically, absorption occurs when a light particle (photon) interacts with an electron andexcites it to a
higher energy level.

Extrinsic Absorption - Extrinsic absorption is caused by impurities introduced into the fiber material.
Trace metal impurities, such as iron, nickel, and chromium, are introduced into the fiber during
fabrication. Extrinsic absorption is caused by the electronic transition of these metal ions from one energy
level to another. Extrinsic absorption also occurs when hydroxyl ions (OH-) are introduced into the fiber.
Water in silica glass forms a silicon-hydroxyl (Si-OH) bond. This bond has a fundamental absorption at
2700 nm. However, the harmonics or overtones of the fundamental absorption occur in the region of
operation. These harmonics increase extrinsic absorption at 1383 nm, 1250 nm, and 950 nm. Figure 2-21
shows the presence of the three OH- harmonics. The level of the OH- harmonic absorption is also
indicated.
These absorption peaks define three regions or windows of preferred operation. The first window is
centered at 850 nm. The second window is centered at 1300 nm. The third window is centered
at 1550 nm. Fiber optic systems operate at wavelengths defined by one of these windows. The amount of
water (OH-) impurities present in a fiber should be less than a few parts per billion. Fiber attenuation
caused by extrinsic absorption is affected by the level of impurities (OH-) present in the fiber. If the
amount of impurities in a fiber is reduced, then fiber attenuation is reduced.
Causes of Extrinsic Absorption:
•Metal impurities, such as iron, nickel, and chromium, are introduced into thefiber during fabrication
cause extrinsic absorption.
•Extrinsic absorption also occurs when hydroxyl ions (OH-) (due to presence of water vapor) are
introduced into the fiber.
•Chromium and copper can cause attenuation in excess of 1 dB/km in the near infra-red region
(~400GHz).
How Extrinsic Absorption can be minimized?
Extrinsic absorption can be minimized by glass refining techniques such as vapor-phase oxidation
whichlargely eliminates the effects of these metallic impurities.Anew kind of glass fiber, known asdry
fiber , the OH ion concentration is reduced tosuch low levels that the 1.39um peak almost disappears. So,
by using Dry fiber Extrinsic absorption can be minimized.

64

Scattering Loss:
•Scattering occurs when light strikes a substance which emits light of itsown at the same wavelength as
the incident light.
•Scatteringis a general physical process where some forms of radiation,such as light are forced to deviate
from a straight line by one or morelocalized non-uniformities in the medium through which they pass.
Inconventional use, this also includes deviation of reflected radiation fromthe angle predicted by the law
of reflection. Reflections that undergoscattering are often calleddiffusereflections.
•Scattering losses are caused by the interaction of light with density fluctuations within a fiber. Density
changes are produced when opticalfibers are manufactured.
•The propagation of light through the core of an optical fiber is based ontotal internal reflection of the
lightwave. Rough and irregular surfaces,even at the molecular level, can cause light rays to be reflected in
randomdirections. This is called diffuse reflection or scattering, and it is typicallycharacterized by wide
variety of reflection angles
Causes of Scattering:
During manufacturing, regions of higher and lower molecular
density areas, relative to the average densityof the fiber,
are created. Light traveling through the fiber interacts with the
density areas as shown in figure.
Light is then partially scattered in all directions.
•Microscopic variations in the material density, compositional
fluctuations,structural inhomogeneities and structural defects
occurring during fiber fabrication causes scattering.
These gives rise to refractive-index variations withinthe glass,
this index variations cause scattering of light.
TYPES:
There are two main types of scattering: linear scattering and nonlinear scattering.
For linear scattering, the amount of light power that is transferred from a wave is proportional to the
power in the wave. It is characterized by having no change in frequency in the scattered wave.
On the other hand, nonlinear scattering is accompanied by a frequency shift of the scattered light.
Nonlinear scattering is caused by high values of electric field within the fiber (modest to high amount of
optical power). Nonlinear scattering causes significant power to be scattered in the forward, backward, or
sideways directions.

65

Rayleigh scattering
Rayleigh scattering (named after the British physicist Lord Rayleigh) is the main type of linear scattering.
It is caused by small-scale (small compared with the wavelength of the Lightwave) in homogeneities that
are produced in the fiber fabrication process. Examples of in homogeneities are glass composition
fluctuations (which results in minute refractive index change) and density fluctuations (fundamental and
not improvable). Rayleigh scattering accounts for about 96% of attenuation in optical fiber.
As light travels in the core, it interacts with the silica molecules in
the core. These elastic collisions between the light wave and the
silica molecules result in Rayleigh scattering. If the scattered light
maintains an angle that supports forward travel within the core, no
attenuation occurs. If the light is scattered at an angle that does not
support continued forward travel, the light is diverted out of the core
and attenuation occurs. Depending on the incident angle, some
portion of the light propagates forward and the other part deviates
out of the propagation path and escapes from the fiber core. Some
scattered light is reflected back toward the light source. This is a
property that is used in an OTDR (Optical Time Domain
Reflectometer) to test fibers.
Causes of Rayleigh Scattering:
•It results from non-ideal physical properties of the manufactured fiber.
•It results from in homogeneities in the core and cladding. Because of these in homogeneities problems
occur like – a ) F l u c t u a t i o n i n r e f r a c t i v e i n d e x
b)density and compositional variations.
How to minimize Rayleigh scattering?
•Rayleigh scattering is caused due to compositional variations which can be reduced by improved
fabrication (Fluctuation of refractive index is caused by the freezing in of density in homogeneities cannot
be avoided.)
Equation of Rayleigh Scattering:Light scattering can be divided into three domains based on a
dimensionless size parameter, α which is defined as:
Α =πDp/ λ
where π D pis the circumference (The boundary line of a circle)of a particle and λ is thewavelength of incident
radiation. Based on the value of α, these domains are:α<<1: Rayleigh scattering (small particle compared
to wavelength of light) α≈1: Mie scattering (particle about the same size as wavelength of light).

66

Mie Scattering (Linear Scattering)
Mie scattering is named after German physicist Gustav Mie. This theory describes scattering of
electromagnetic radiation by particles that are comparable in size to a wavelength (larger than 10% of
wavelength).For particles much larger, and much smaller than the wavelength of scattered light there are
simple and excellent approximations that suffice.
For glass fibers, Mie scattering occurs in in homogeneities such as core-cladding refractive index
variations over the length of the fiber, impurities at the core-cladding interface, strains or bubbles in the
fiber, or diameter fluctuations. Mie scattering can be reduced by carefully removing imperfections from
the glass material, carefully controlling the quality and cleanliness of the manufacturing process. In
commercial fibers, the effects of Mie scattering are insignificant. Optical fibers are manufactured with
very few large defects. (larger than 10% of wavelength).
Causes of Mie Scattering:
•Occurred due to inhomogeneities in the composition of silica. (i.e., inhomogeneities in the density of
SiO2).
•Irregularities in the core-cladding interface.
•Difference in core cladding refractive index.
•Diameter fluctuations.
•Due to presence of strains and bubbles.

How Mie scattering can be minimized?
•Removing imperfection due to glass manufacturing process
•Carefully controlled extrusion(To push or thrust out) and coating of the fiber

Brillouin Scattering (Nonlinear Scattering)
Brillouin scattering is caused by the nonlinearity of a medium. In glass fibers,
Brillouin scattering shows as a modulation of the light by the thermal energy in
the material. An incident photon can be converted into a scattered photon of
slightly lower energy, usually propagating in the backward direction, and a
phonon (vibrational energy). This coupling of optical fields and acoustic waves
occurs via electrostriction.
The frequency of the reflected beam is slightly lower than that of the incident
beam; the frequency difference vB corresponds to the frequency of emitted
phonons. This is called Brillouin Frequency Shift. This phenomenon has been used for fiber optic sensor
applications.

67

Bending loss
Bending loss occurs in two forms – macro bending and micro bending. When a cable is bent and it
disrupts the path of the light signal, bending loss occurs. The tighter the bends of the cable, greater is the
loss.
Macro bends: It describes the bending of the fiber optic cable in a tight
radius. The bend curvature creates an angle that is too sharp for the light to
be reflected back into the core, and some of it escapes through the fiber
cladding, causing optical loss. This optical loss increases rapidly as the
radius is decreased to an inch or less.

Micro bends: These refer to the minute but severe bends in the fiber that
results in light displacement and increased loss, it is typically caused by
pinching or squeezing the fiber. Micro bends deform the fiber’s core
slightly, causing light to escape at these deflections. Most micro bending
can be avoided by the correct selection of materials and proper cabling,
handling and installation techniques.

Insertion loss (IL)
It is the most important performance indicator of a fiber optic interconnection. This is the loss of light
signal, measured in decibels(dB), during the insertion of a fiber optic connector.
Some of the common causes of insertion loss include:
1. The misalignment of ferrules during connections.
2. The air gap between two mating ferrules.
3. Absorption loss from impurities such as scratches and oil contamination.
Insertion loss can be minimized by proper selection of interconnect materials, good polishing and
termination process of fiber connectors.

68

Return loss (RL)
Return loss, which is also known as back reflection, is the loss of light signal that is reflected back to the
light source. This occurs as the light is reflected off the connector and travels back along the fiber to the
light source. This phenomenon is also known as Fresnel’s reflection. It occurs also when there are
changes in the refractive index of materials in which light travels, such as the fiber core and the air gap
between fiber interconnection. When light passes through these two different refractive indexes, some of
the light is reflected back.
The greater the difference between the refractive indexes of the materials, the higher the loss.

DISPERSION
In digital communication systems, information is encoded in the form of pulses and then these light
pulses are transmitted from the transmitter to the receiver. The larger the number of pulses that can be
sent per unit time and still be resolvable at the receiver end, the larger is the capacity of the system.
However, when the light pulses travel down the fiber, the pulses spread out, and this phenomenon is
called Pulse Dispersion. Pulse dispersion is shown in the following figure.

69

Chromatic Dispersion
Chromatic dispersion represents the fact that different colors or wavelengths travel at different speeds,
even within the same mode. Chromatic dispersion is the result ofmaterial dispersion, waveguide
dispersion, or profile dispersion. Figure 1 below shows chromatic dispersion along with key component
waveguide dispersion and material dispersion. The example shows chromatic dispersion going to zero at
the wavelength near 1550 nm. This is characteristic of bandwidth dispersion-shifted fiber. Standard fiber,
single-mode, and multimode have zero dispersion at a wavelength of 1310 nm.
Every laser has a range of optical wavelengths, and the speed of light in fused silica (fiber) varies with the
wavelength of the light. Since a pulse of light from the laser usually contains several wavelengths, these
wavelengths tend to get spread out in time after traveling some distance in the fiber. The refractive index
of fiber decreases as wavelength increases, so longer wavelengths travel faster. The net result is that the
received pulse is wider than the transmitted one, or more precisely, is a superposition of the variously
delayed pulses at the different wavelengths. A further complication is that lasers, when they are being
turned on, have a tendency to shift slightly in wavelength, effectively adding
someFrequencyModulation(FM) to the signal. This effect, called "chirp," causes the laser to have an even
wider optical line width. The effect on transmission is most significant at 1550 nm using non-dispersionshifted fiber because that fiber has the highest dispersion usually encountered in any real-world
installation.

Polarization Mode Dispersion
Polarization mode dispersion (PMD) is another complex optical effect that can occur in single-mode
optical fibers. Single-mode fibers support two perpendicular polarizations of the original transmitted
signal. If it were perfectly round and free from all stresses, both polarization modes would propagate at
exactly the same speed, resulting in zero PMD. However, practical fibers are not perfect; thus, the two
perpendicular polarizations may travel at different speeds and, consequently, arrive at the end of the fiber
at different times. Figure 3 illustrates this condition. The fiber is said to have a fast axis, and a slow axis.
The difference in arrival times, normalized with length, is known as PMD (ps/km0.5). Excessive levels of
PMD, combined with laser chirp and chromatic dispersion, can produce time-varying composite second
order (CSO) distortion in amplitude modulated (AM) video systems. This results in a picture that may
show a rolling or intermittent diagonal line across the television screen. Like chromatic dispersion, PMD
causes digital transmitted pulses to spread out as the polarization modes arrive at their destination at
different times. For digital high bit rate transmission, this can lead to bit errors at the receiver or limit
receiver sensitivity.

70

These two polarization modes are identical in a perfectly symmetrical fiber. Stresses within the fiber, and
forces applied to it from the outside world, cause the refractive index of glass (thus velocity) to differ very
slightly for light in the two polarization modes. Thus these two polarization modes arrive at slightly
different time at the end of the fiber. This is called Polarization Mode Dispersion is smaller in magnitude
than material dispersion, so it hasn’t been a problem until recently high speed long distance single mode
fiber systems becomes popular. PMD is a serious problem when data rate exceeds 2.5 Gb/s

MODAL DISPERSION
Modal dispersion is a distortion mechanism occurring in multimode fibers and other waveguides, in
which the signal is spread in time because the propagation velocity of the optical signal is not the same
for all modes. Other names for this phenomenon include multimode distortion, multimode
dispersion, modal distortion, intermodal distortion, intermodal dispersion, and intermodal delay
distortion.
In the ray optics analogy, modal dispersion in a step-index optical fiber may be compared to multipath
propagation of a radio signal. Rays of light enter the fiber with different angles to the fiber axis, up to
the fiber's acceptance angle. Rays that enter with a shallower angle travel by a more direct path, and
arrive sooner than rays that enters at a steeper angle (which reflects many more times off the
boundaries of the core as they travel the length of the fiber). The arrival of different components of the
signal at different times distorts the shape.
Modal dispersion limits the bandwidthof multimode fibers. For example, a typical step-index fiber
with a 50 µm core would be limited to approximately 20 MHz for a one kilometer length, in other
words, a bandwidth of 20 MHz·km. Modal dispersion may be considerably reduced, but never
completely eliminated, by the use of a core having a graded refractive indexprofile. However,
multimode graded-index fibers having bandwidths exceeding 3.5 GHz·km at 850 nm are now
commonly manufactured for use in 10 Gbit/s data links.
Modal dispersion should not be confused with chromatic dispersion, a distortion that results due to the
differences in propagation velocity of different wavelengths of light. Modal dispersion occurs even
with an ideal, monochromatic light source.
A special case of modal dispersion is polarization mode dispersion (PMD), a fiber dispersion
phenomena usually associated with single-mode fibers. PMD results when two modes that normally
travel at the same speed due to fiber core geometric and stress symmetry (for example, two orthogonal
polarizations in a waveguide of circular or square cross-section), travel at different speeds due to
random imperfections that break the symmetry.

71

SPLITTER

A splitter is a device used to split the cable signal if the signal must be sent to two or more devices.
Bright House Networks service technicians might install splitters if they activate additional outlets
within your home. You can install or remove splitters on your own, but it is not recommended. For
your equipment to work properly with your Bright House Networks equipment and provide clear
reception, it must meet proper signal requirements. A service technician can ensure that your
equipment is receiving the proper signal level.
Optical splitters are also known as couplers. They are base on the type of cable management product
they will be using.
Performance specifications of the splitters are given by the ITU- T G671 standard.
They are of two types – 1. Fused Biconical Taper Splitters
2. Planar Lightwave Circuits
Due to high losses associated with optical splitters, higher power levels are required when high levels
of span is required.
In many cases, the splitters are housed in cassettes for easy handling and expansion of fiber
distribution hubs and patch panels.

TYPES OF
SPLITTERS

FUSED
BICONICAL
TAPER
SPLITTERS

PLANAR
LIGHTWAVE
CIRCUITS

72

FUSED BICONICAL TAPER SPLITTERS
It is the most common and easiest form of splitter manufacture.
These splitters are wavelength independent and add only loss.
These are also known as singlemode splitters.
Singlemode splitters are quality components designed to divide or combine optical signal in an
optical fiber system.
These devices are fabricated by using the FBT process and are reliable over wide range of
temperature.
Operating wavelength is 1310nm or1550nm and the passband is 80nm.
The coupling ratio can change from 1:99 to 50:50.

Features:
Low insertion loss.
Low excess loss.
Low PDL.
High directivity.
Long haul reliability.
Customer defined specifications.
Compact and accurate design.
Low polarization related loss.
More channels.
Wide operation wave-length range.
Wide operation temperature range.
Package and shape could be made as customer requested.
Applications:
FTTH system.
LAN/ WAN/ MAN network system.
Analog/ digital passive optical network.
Cable television (CATV).

73

Specifications:
Coupling ratio

1/99 to 50/50

Directivity

> 50 dB (1X2)
> 60 dB (2X2)

Reflectance

< -55 Db

PDL

< 0.1dB (<0.3dB for tap legs of <15%)

Operating band pass

+/- 40 nm

Operating temperature

-40° to +85° C

Storage temperature

-55° to +85° C

Standard lead length

1 meter

Grade A

IL: 0.1 dB
IL*

Uniformity

1x2 or 2x2

50/50

3.40

0.6

1x2 or 2x2

45/55

3.90 / 2.90

n/a

1x2 or 2x2

40/60

4.40 / 2.50

n/a

1x2 or 2x2

35/65

5.10 / 2.20

n/a

1x2 or 2x2

30/70

5.80 / 1.80

n/a

1x2 or 2x2

25/75

6.70 / 1.60

n/a

1x2 or 2x2

20/80

7.60 / 1.10

n/a

1x2 or 2x2

15/85

9.00 / 0.96

n/a

1x2 or 2x2

10/90

11.00 / 0.63

n/a

1x2 or 2x2

5/95

14.60 / 0.40

n/a

1x2 or 2x2

4/96

15.27 / 0.37

n/a

1x2 or 2x2

3/97

16.63 / 0.34

n/a

1x2 or 2x2

2/98

2/98 18.53 / 0.30

n/a

1x2 or 2x2

1/99

21.6 / 0.30

n/a

74

Understanding the basics of optical fibers

Understanding the basics of optical fibers

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