1

TABLE OF CONTENTS Content Page No. Table of Contents………………………………………………………………...................................v

Table Index…………………………………………………………………........................................vii

Figure Index………………………………………………………………….....................................viii

Abstract……………………………………………………………………………………………….......ix

Content Page No.

CHAPTER 1: INTRODCUTION .....................................................................1-3

1.1 Overview 1

1.2 Vision & Mission 2

1.3 Products & Services 2

1.4 Projects, Revenue, Growth Plan 3

CHAPTER 2: INTRODUCTION TO OFC.....................................................4-15

2.1 History of OFC 4-5

2.2 Elements of Optical Fibre 5-6

2.3 Fiber Optic Link Components 7-11

2.4 How Optical Fibre works 12

2.5 Advantage of OFC 12-14

2.6 Application of OFC 15

CHAPTER 3: DESIGNING OF OPTICAL FIBRE.....................................16-27

3.1 Structure of Optical Fibre 16-18

3.2 Types of Optical Fibre 18-23

3.2.1 Single Mode Fibre 18-19

3.2.2 Multi-Mode Fibre 19-20

3.2.3 Single Mode v/s Multi-Mode 21-23

3.3 Types of Optical Fibre & Colour Coding 25-27

CHAPTER 4: OPTICAL NETWORKS........................................................28-34

2

4.1 Passive Optical Network (PON) 28-31

4.1.1 FTTH 29-30

4.1.2 FTTC 30

4.1.3 FTTP 30

4.2 Synchronous Optical Network (SONET) 31-34

4.2.1 SONET/SDH Protocol Overview 31-32

4.2.2 SONET Multiplexing 32-33

4.2.3 Benefits of SONET 33-34

Chapter 5: OPTICAL FIBRE INSTALLATION.........................................35-39

5.1 Introduction 35

5.2 Surveying & Preparing area root map. 35-36

5.3 Trenching & laying of Duct 37-38

5.4 Cable Jetting 38-39

Chapter 6: SPLICING OF OPTICAL FIBRE…………………………...40-47

6.1 Introduction 40

6.2 Fusion Splicing 40-43

6.3 Mechanical Splicing 44-47

6.4 Fusion v/s Mechanical Splicing 47

Chapter 7: POWER MEASUREMENT........................................................48-54

7.1 Introduction 48

7.2 Types of Power losses 49-52

7.2.1 Extrinsic Power Losses 49-51

7.2.2 Intrinsic Power Losses 51-52

7.3 Power Loss Measurement 52-55

7.3.1 Power Meter 53-54

7.3.2 OTDR 54

Chapter 8:CONCLUSION..................................................................................55

Chapter 9: REFERENCES.............................................................................56-57

3

Table Index

Sr. No.

Table No.

Topic

Page No.

1

2.1

FTTH Data speed

13

2

2.2

Comparison between ADSL, Wireless & Fiber

14

3

3.1

Outer jacket colour coding

27

4

3.2

Fiber positioning colour coding

27

5

6.1

Difference between Mechanical & Fusion

splicing

48

4

Figure Index

Sr. No. Fig. No. Topic Page No.

1 2.1 Optical Loss Curve 4

2 2.2 Optical Fiber Cross Section 5

3 2.3 Fiber Optic Link 7

4 2.4 Fusion Splicer 10

5 2.5 Optical Connectors 11

6 2.6 TIR 12

7 3.1 Fiber Structure 16

8 3.2 Light propagation in SMF & MMF 21

9 3.3 SMF & MMF Cross section 22-23

10 3.4 Types of cables 24-26

11 4.1 PON 28

12 4.2 FTTx study 30

13 4.3 SONET Network 32

14 4.4 SONET Multiplexing Hierarchy 33

15 5.1 Google street view 35

16 5.2 Trenching 37

17 5.3 Cable Jetting 39

18 6.1 Fusion Arc description 42

19 6.2 Cleaver 42

20 6.3 Strippers 42

21 6.4 Fusion splicer schematic 43

22 6.5 Mechanical Splicing 44

23 7.1 Bending Loss 50

24 7.2 Connector Loss 50

25 7.3 Power Meter 53

26 7.4 OTDR 54

5

CHAPTER 1

INTRODUCTION

1.1 Overview of Company

a) AKSH OPTIFIBRE LTD. was founded in 1986 with major focus on manufacturing of

Optical Fiber Cables.

b) It is a 27-year-old company which started manufacturing of optical fiber and optical

fiber cables (OFC) in 1994.

c) In 1996-97 AKSH acquired Fiber Reinforced Plastic Rods (FRP) business which is a

key raw material for Optical Fiber Cables.

d) AKSH went Public in the year 2000 and is listed on National Stock Exchange (NSE)

and Bombay Stock Exchange (BSE).

e) AKSH has two plants at Bhiwadi, Rajasthan for Fiber & Optical Fiber Cables, and one

plant at Reengus, Rajasthan for Fiber Reinforced Plastic Rods (FRP).

f) AKSH is now the largest FRP rod producer, supplying to all optical fiber cable

manufacturers in 56 countries across six continents. All the manufacturing facilities

are ISO 9001 and ISO 14001 certified.

g) AKSH specialize in manufacturing of various optical fiber cables like aerial, duct,

armoured, indoor and outdoor FTTH drop cables meeting all the International ITU-T

standards.

h) AKSH is active in the development, design, manufacturing, supply and installation of

cable solutions. Strongly positioned in high-tech markets, we have the wide range of

products, services, technologies and know-how in the telecom market- providing all

types of optical fiber cables and accessories for the telecoms - voice, video and data

transmission - industry.

i) With leading Indian market share, AKSH boasts of strong customer base comprising state

owned companies in India like BSNL, VSNL, MTNL, Railways, Defence etc. AKSH

exports to a host of diversified destinations in USA, South America, Europe, CIS,

Africa, and Middle East & Asia. And has won two major international tenders.

j) Along with many international approvals, AKSH is also member of the FTTH council.

k) AKSH shifted from a Vertical structure to Horizontal structure in which we have merely

four levels between the chairman and the lowest level in the company, i.e. MD, General

Manager and CFO, Process Leader, and Process Associate.

6

1.2 Vision & Mission

Vision: -

To become a global leader in enabling simple innovative smart living.

Mission: -

a) To promote a learning culture which emerges as an educational enterprise for

improving individual and collective performance and for acquiring competencies to

meet the challenges in the changing business scenario.

b) To encourage members to contribute ideas and develop an attitude to respect

divergent views. To facilitate communication across levels and enable members to

accept smart mistakes openly.

c) To make working transparent by defining policies, systems and processes and lower

the role of discretion. Process/activity can be accountable.

d) To strengthen customer orientation not only externally but internally as well. To work

towards the delight of both internal and external customers.

1.3 Products & Services

a) AKSH OPTIFIBRE LIMITED is one of the leading providers of transmission solutions

for the telecom industries globally.

b) Various products & services are embedded in our diversified portfolio. Our products

include optical fibers, optical fiber cables, cable reinforcement solutions while we

also deliver some of the exemplary services that include iControl (IPTV), Pigeon

(VoIP) and FTTH.

c) AKSH has been innovative with its cable designs and manufactures a wide array of

Optical Fiber Cables that include Single Mode & Multimode Cables, Duct Cables,

Armoured, FTTH (Aerial installations & fibre to home) Cables, Indoor & Outdoor

Cables and Special application cables (Hybrid, All purpose, Ceramic Armoured cables).

d) AKSH holds a reputation of being the pioneer in manufacturing of raw materials for

optical fiber cables and is globally renowned for high quality FRP (Fiber reinforced

plastic) Rods, ARP (Aramid reinforced plastic) rods and WS yarn (water blocking yarn)

that gives the best reinforcement and strength to Optical Fiber Cables.

7

e) In 2002, AKSH started its 1st Fiber to the Home (FTTH) in Jaipur and later collaborated

with MTNL & BSNL in Jan. 2010 to launch its 1st FTTH project in Jaipur. Similar

projects are started in Delhi and Mumbai in collaboration with MTNL and in Ajmer,

Faridabad and Gurgaon in collaboration with BSNL.

1.4 Projects, Revenue & Growth Plan

Projects: -

a) AKSH has been successfully completed the assignment installing of 2600 Km of All

Dielectric Self Supporting (ADSS) optical fibre cable in Bhutan under Bhutan Power

Corporation Limited.

b) In Mauritius, AKSH has received contract from BTL Mauritius to supply and install

FTTH triple play equipment.

c) In 2002, AKSH started its 1st Fibre to the Home (FTTH) in Jaipur and later collaborated

with MTNL & BSNL in Jan 2010 to launch its 1st FTTH project in Jaipur.

d) In 2011, the first ever IPTV service in Rajasthan was launched by AKSH in collaboration

with BSNL.

Revenue: -

AKSH Optifibre Limited reports strong financial results for Q4 FY16 & FY 2015-16.

Revenue increased by 23% to Rs. 462 crores, New Delhi, May 30, 2016.

Growth Plan: -

a) By 2020 AKSH aiming towards to complete takeover of the IPTV business all over

India.

b) Also, contributing towards the Make in India initiative of our government, AKSH is

aiming eye on the largest manufacturer and exporter of FRP Rods and Armoured

cable in India.

8

CHAPTER 2

INTRODUCTION TO OFC

2.1 History of OFC

a) In the late 19th and early 20th centuries, light was guided through bent glass rods to

illuminate body cavities. Alexander Graham Bell invented a 'Photo-phone' to transmit

voice signals over an optical beam.

b) By 1964, a critical and theoretical specification was identified by Dr. Charles K. Kao for

long-range communication devices, the 10 or 20 dB of light loss per kilometre standard.

c) The first challenge undertaken by scientists was to develop a glass so pure that one

percent of the light would be retained at the end of one kilometre (km), the existing

unrepeated transmission distance for copper-based telephone systems. In terms of

attenuation, this one-percent of light retention translated to 20 decibels per kilometre

(dB/km) of glass material.

d) Glass researchers all over the world worked on the challenge in the 1960s, but the

breakthrough came in 1970, when Corning Incorporated scientists Dr. Robert Maurer,

Donald Keck, and Peter Schultz created a fiber with a measured attenuation of less than

20 dB per km. It was the purest glass ever made.

e) In April 1977, General Telephone and Electronics tested and deployed the world's first

live telephone traffic through a fiber-optic system running at 6 Mbps, in Long Beach,

California. They were soon followed by Bell in May 1977, with an optical telephone

communication system installed in the downtown Chicago area, covering a distance of

1.5 miles.

f) Figure 2.1 shows three curves. The top, dashed, curve corresponds to early 1980’s fiber,

the middle, dotted, curve corresponds to late 1980’s fiber, and the bottom, solid, curve

corresponds to modern optical fiber.

Fig. 2.1: Optical Loss Curve [1]

9

The earliest fiber optic systems were developed at an operating wavelength of about 850

nm. This wavelength corresponds to the so-called “first window” in a silica-based optical

fiber. This window refers to a wavelength region that offers low optical loss. It sits

between several large absorption peaks caused primarily by moisture in the fiber

and Rayleigh scattering.

g) Most companies jumped to the “second window” at 1310 nm with lower attenuation of

about 0.5 dB/km. In late 1977, Nippon Telegraph and Telephone (NTT) developed the

“third window” at 1550 nm. It offered the theoretical minimum optical loss for silica-

based fibers, about 0.2 dB/km.

h) Today, 850 nm, 1310 nm, and 1550 nm systems are all manufactured and deployed along

with very low-end, short distance, systems using visible wavelengths near 660 nm.

i) The shortest link lengths can be handled with wavelengths of 660 nm or 850 nm. The

longest link lengths require 1550 nm wavelength systems. A “fourth window,” near 1625

nm, is being developed. While it is not lower loss than the 1550 nm window, the loss is

comparable.

2.2 Elements of Optical Fiber

An optical fiber is a thin, flexible, transparent fiber that acts as a waveguide, or "light pipe",

to transmit light between the two ends of the fiber. Optical fibers are widely used in fiber-

optic communications, which permits transmission over longer distances and at higher

bandwidths (data rates) than other forms of communication. Fibers are used instead of metal

wires because signals travel along them with less loss and are also immune to

electromagnetic interference.

Fig. 2.2: Fiber cross-section [2]

10

a) 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. The three most common core sizes are:

(i) 9 µm diameter (single-mode)

(ii) 50 µm diameter (multi-mode)

(ii) 62.5 µm diameter (multi-mode)

b) Cladding –

The fibers are coated with a glass of slightly lower refractive index. This is known

as cladding. The cladding increases the critical angle within the core fiber and also

prevents adjacent fibers from touching each other. At every point of contact light would

escape into another fiber.

c) Coating –

The coating is the first non-optical layer around the cladding. The coating typically

consists of one or more layers of polymer that protect the silica structure against physical

or environmental damage. The coating is stripped off when the fiber is connectorized or

fusion spliced.

d) Strengthening fibers –

These components help protect the core against crushing forces and excessive tension

during installation. The materials can range from Kevlat4 to wire strands to gel-filled

sleeves.

e) Jacket –

The jacket is an important feature of the fiber. It is 900 microns and helps protect the

fiber from breaking during installation and termination and is located outside of the

coating.

2.3 Fiber Optic Link Components

In order to comprehend how fiber optic applications work, it is important to understand the

components of a fiber optic link. Simplistically, there are four main components in a fiber

optic link.

a) Optical Transmitter

b) Optical Fiber/Cable

c) Connectors

d) Optical Reciever

11

Fig. 2.3: Optical link path [3]

a) Optical Transmitter-

The transmitter converts the electrical signals to optical. A transmitter contains a light

source such as a Light Emitting Diode (LED) or a Laser (Light Amplification by

Stimulated Emission of Radiation) diode, or a Vertical Cavity Surface Emitting Laser

(VCSEL).

(i) LED: Is used in multimode applications and has the largest spectral width that

carries the least amount of bandwidth.

Fig. 2.4: LED Beam [2]

(ii) VCSEL: Is also used in multimode applications with a narrower spectral width

that can carry more bandwidth than the LED.

Fig. 2.5: VCSEL Beam [3]

12

(iii) LASER: Has the smallest spectral width, carries the most bandwidth, and is used

in single mode applications.

Fig. 2.6: Laser Beam [2]

These sources produce light at certain wavelengths depending upon the materials

from which they are made. Most fiber optic sources use wavelengths in the infrared

band, specifically 850nm (1nm=10-9m), 1300nm and 1550nm. For reference, visible

light operates in the 400-700nm range (see Fig.2.7).

Fig. 2.7: Spectrum[2]

b) Optical Fiber/Cable-

In this section, we discuss the structure and properties of an optical fiber, how it guides

light, and how it is cabled for protection.

An optical fiber is made of 3 concentric layers (see Figure 2.8)

13

(i) Core: This central section, made of silica or doped silica, is the light transmitting

region of the fiber.

(ii) Cladding: This is the first layer around the core. It is also made of silica, but not

the same composition as the core. This creates an optical waveguide which

confines the light in the core by total internal reflection at the core-cladding

interface.

(iii) Coating: The coating is the first non-optical layer around the cladding. The

coating typically consists of one or more layers of polymer that protect the

silica structure against physical or environmental damage. The coating is

stripped off when the fiber is connectorized or fusion spliced.

Fig. 2.8: Fiber geometry [3]

(iv) Buffer (not pictured): The buffer is an important feature of the fiber. It is 900

microns and helps protect the fiber from breaking during installation and

termination and is located outside of the coating.

c) Connectors-

Fiber optic links require a method to connect the transmitter to the fiber optic cable and

the fiber optic cable to the receiver. In general, there are two methods to link optical

fibers together.

Fusion Splice: The first method is called a fusion splice. This operation consists of

directly linking two fibers by welding with an electric arc or a fusion splicer (see

Figure 2.9). The advantages of this approach are that the linking method is fast and

simple and there is very little insertion loss (the loss of light generated by a

connection is called Insertion Loss [IL]). The disadvantages are that the link is

relatively fragile, is permanent, and the initial cost (of the fusion splicer) is high.

14

Fig. 2.9: Splicer tool [3]

Connectors- The second method involves the uses of fiber optic connectors. A

connector terminates the optical fiber inside a ceramic ferrule, using epoxy to

hold the fiber in place. The connectors can be mated and unmated at any time.

The advantages of this approach are that the connection is robust, the connector

can be chosen according to the application, and the connector can be connected

and disconnected hundreds or even thousands of time without damaging the

connectors. The disadvantages of this approach are that the connectorization takes

longer than fusion splicing, requires special tools, and the insertion loss can be

higher when compared with fusion splicing.

There are two types of fiber optic connectors: physical contact and expanded

beam.

(i) Physical Contact Connectors- Physical contact connectors utilize fiber in

a tightly tolerance ceramic ferrule. This allows easy handling of the fiber

and protects it from damage. The principle of physical contact connectors

involves the direct contact of polished fibers within two ceramic ferrules.

The ferrules are aligned using a ceramic alignment sleeve (see Figure

2.10). Insertion loss is a function of the alignment accuracy and the polish

quality. There are springs behind the ferrule to ensure that the two ferrules

are in constant contact even in high vibration and shock environments.

15

Fig. 2.10: Contact connector [5]

(ii) Expanded Beam Technology- The other connector technology is

expanded beam, which consists of placing a lens at the exit of each fiber to

widen and collimate the light. In this configuration, there is an air gap

between the optical fibers/lens assemblies (see Figure 2.11). The loss

generated by an expanded beam connection is more than that of a physical

contact connector due to the lenses, mechanical alignment and sometimes

protective windows (approximately 0.8 to 2.5dB typical). This type of

connector performs well against particle contamination on the lens

because the beam is expanded to a much larger size than the beam that

comes directly from a fiber.

Fig. 2.11: Expanded beam [5]

d) Optical Receiver-

The last component of the fiber optic link is the optical receiver, which uses a photodiode

to convert the optical signals into electrical. The two types of photodiodes used are:

Positive Intrinsic Negative (PIN) and the Avalanche Photo Diode (APD).

16

2.4 How Optical Fiber Works

The operation of an optical fiber is based on the principle of total internal reflection (See fig.

2.12) Light reflects (bounces back) or refracts (alters its direction while penetrating a

different medium), depending on the angle at which it strikes a surface.

The angle of refraction at the interface between two media is governed by Snell’s law:

2211 sinsin nn

Fig. 2.12: Snell’s Law [3]

The light is "guided" down (see Figure 2.13) the core of the fiber by the optical "cladding"

which has a lower refractive index (the ratio of the velocity of light in a vacuum to its velocity

in a specified medium) that traps light in the core through "total internal reflection."

Fig. 2.13: TIR in Fiber [3]

17

2.5 Advantage of OFC

OFC has obvious advantages for the consumer, both today and in the foreseeable future,

offering improved performance for broadband services in comparison with those currently

delivered primarily over copper networks.

a) Speed: The speed comparison factor might be the most convincing one for you as

customers. OFC provides the highest possible speeds of Internet access downstream

(from the network to the end user) as well as upstream (from the user to the network).

Mobile connections are much slower than OFC, especially when several users are in the

same area and share the available network. Satellite connections are also much slower

than FTTH: they entail a delay, which hampers phone conversations and other

interactive activities. Other fixed technologies, like ADSL, use metal wires - which are

about 100 times slower than fibre to the home – to connect your home to the fiber city

network.

Keeping in mind that FTTH allows at least 1 Gbps download and 1 Gbps upload, the

following table drawn by the FTTH Council Europe shows typical download and upload

speeds for photo and video transfer for different bandwidth combination:

Table 2.1: FTTH Data speed [4]

Time taken for: 1 GB photo album 4.7 GB standard video 25 GB HD Video

1 Gbps download

1 Gbps upload

9 sec.

39 sec. 3 min 28 sec.

100 Mbps download

100 Mbps upload

1 min 23 sec. 6 min 31 sec. 34 in 40 sec.

50 Mbps download

10 Mbps upload

2 min 46 sec.

13 min 52 sec.

13 min 2 sec.

1 hr 5 min.

1 hr 9 min.

5 hr 47 min.

8 Mbps download

1 Mbps upload

19 min.

2 hr 32 min.

1 hr 29 min.

11 hr 54 min.

7 hr 55 min.

-

b) Reliability: Even though OFC speed is remarkable, we should consider other factors that

also impact on the end user service. Reliability is definitely one of these factors. An

FTTH broadband connection offers an improved network reliability.

18

c) Security: The reliability factor is linked with security. Magnetic fields don't just generate

noise in signal carrying conductors; they also make it possible to leak out the

information that is on the conductor. There are no radiated magnetic fields around

optical fibers; the electromagnetic fields are confined within the fiber. That makes it

impossible to tap the signal being transmitted through a fiber without cutting into the

fiber. Secure fiber networks can therefore help protect content from piracy when other

broadband solutions are more likely subject to these kinds of virtual threats or even

viruses.

Fiber offers many advantages when looking at the active network, as shown in the

following table (Table 2.2)

Table 2.2: Comparison between ADSL, Wireless & Fiber [4]

ADSL Wireless Fiber

Pros- Copper cables are

already there.

Pros- Ideal for non-reachable

places.

No cable needs to be

developed.

Pros- More Bandwidth

Reliability

Flexibility

High Security

Longer economic life

More types of services

possible with fiber

Cons- Loss in signal strength

Less secure

Low bandwidth

Cons- Less secure

Low bandwidth

Cons- Fibre optic cable are not

there yet, they need to be deployed.

19

2.6 Application of OFC

Fiber optic cables find many uses in a wide variety of industries and applications. Some uses

of OFC include:

Medical: Used as light guides, imaging tools and also as lasers for surgeries.

Defence/Government: Used as hydrophones for seismic and SONAR uses, as wiring in

aircraft, submarines and other vehicles and also for field networking.

Data Storage: Used for data transmission.

Telecommunications: Fiber is laid and used for transmitting and receiving purposes.

Networking: Used to connect users and servers in a variety of network settings and help

increase the speed and accuracy of data transmission.

Industrial/Commercial: Used for imaging in hard to reach areas, as wiring where EMI is an

issue, as sensory devices to make temperature, pressure and other measurements, and as

wiring in automobiles and in industrial settings.

Broadcast/CATV: Broadcast/cable companies are using fiber optic cables for wiring

CATV, HDTV, internet, video on-demand and other applications.

Fiber optic cables are used for lighting and imaging and as sensors to measure and monitor a

vast array of variables. Fiber optic cables are also used in research and development and

testing across all the above mentioned industries.

20

CHAPTER 3

DESIGNING OF OPTICAL FIBER

3.1 Structure of Optical Fiber

The composition of the cladding glass relative to the core glass determines the fiber's

ability to reflect light. That reflection is usually caused by creating a higher refractive index

in the core of the glass than in the surrounding cladding glass. The refractive index of the

core is increased by slightly modifying the composition of the core glass, generally by

adding small amounts of a dopant. Figure. (3.1) is the graphical description of inside of

optical fiber. It shows that how light behave inside the fiber.

Fig. 3.1: Fiber structure [6]

The first step in manufacturing glass optical fibers is to make a solid glass rod, known as a

preform. Ultra-pure chemicals -- primarily silicon tetrachloride (SiCl4) and germanium

tetrachloride (GeCl4) -- are converted into glass during preform manufacturing.

These chemicals are used in varying proportions to fabricate the core regions for the

different types of preforms.

The basic chemical reaction of manufacturing optical glass is:

21

SiCl4 (gas) + O2 > SiO2 (solid) + 2Cl2 (in the presence of heat)

GeCl4 (gas) + O2 > GeO2 (solid) + 2Cl2 (in the presence of heat)

The core composition of all standard communication fibers consists primarily of silica, with

varying amounts of germania added to increase the fiber's refractive index to the desired

level. Single-mode fibers typically have only small amounts of germania and have a uniform

composition within the core. Multimode fibers typically have a much higher refractive

index, and therefore much higher germania content. Also, the core composition and the

refractive index of graded-index multimode fibers changes across the core of the fiber to

give the refractive index a parabolic shape.

3.1.1 Two basic cable designs are:

Loose-tube cable, used in the majority of outside-plant installations in North America, and

tight-buffered cable, primarily used inside buildings.

The modular design of loose-tube cables typically holds up to 12 fibers per buffer tube with

a maximum per cable fiber count of more than 200 fibers. Loose-tube cables can be all-

dielectric or optionally armoured. The modular buffer-tube design permits easy drop-off of

groups of fibers at intermediate points, without interfering with other protected buffer tubes

being routed to other locations. The loose-tube design also helps in the identification and

administration of fibers in the system.

Single-fiber tight-buffered cables are used as pigtails, patch cords and jumpers to terminate

loose-tube cables directly into opto-electronic transmitters, receivers and other active and

passive components.

Multi-fiber tight-buffered cables also are available and are used primarily for alternative

routing and handling flexibility and ease within buildings.

a) Loose-Tube Cable

In a loose-tube cable design, color-coded plastic buffer tubes house and protect optical fibers.

A gel filling compound impedes water penetration. Excess fiber length (relative to buffer

tube length) insulates fibers from stresses of installation and environmental loading. Buffer

tubes are stranded around a dielectric or steel central member, which serves as an anti-

buckling element.

The cable core, typically uses aramid yarn, as the primary tensile strength member. The outer

polyethylene jacket is extruded over the core. If armouring is required, a corrugated steel tape

is formed around a single jacketed cable with an additional jacket extruded over the armour.

Loose-tube cables typically are used for outside-plant installation in aerial, duct and direct-

buried applications.

22

b) Tight-Buffered Cable

With tight-buffered cable designs, the buffering material is in direct contact with the fiber.

This design is suited for "jumper cables" which connect outside plant cables to terminal

equipment, and also for linking various devices in a premises network.

Multi-fiber, tight-buffered cables often are used for intra-building, risers, general building

and plenum applications.

The tight-buffered design provides a rugged cable structure to protect individual fibers during

handling, routing and connectorization. Yarn strength members keep the tensile load away

from the fiber.

As with loose-tube cables, optical specifications for tight-buffered cables also should include

the maximum performance of all fibers over the operating temperature range and life of the

cable. Averages should not be acceptable

3.2 Types of Optical Fiber

There are two main types of fiber optic cables:-

a) Single Mode Fiber (SMF)

b) Multi-Mode Fiber (MMF)

3.2.1 Single Mode Fiber (SMF):

A single-mode optical fiber (SMF) is an optical fiber designed to carry light only directly

down the fiber - the transverse mode. Modes are the possible solutions of the Helmholtz

equation for waves, which is obtained by combining Maxwell's equations and the boundary

conditions.

These modes define the way the wave travels through space, i.e. how the wave is distributed

in space. Waves can have the same mode but have different frequencies. This is the case in

single-mode fibers, where we can have waves with different frequencies, but of the same

mode, which means that they are distributed in space in the same way, and that gives us a

single ray of light. Although the ray travels parallel to the length of the fiber, it is often

called transverse mode since its electromagnetic vibrations occur perpendicular (transverse)

to the length of the fiber.

The 2009 Nobel Prize in Physics was awarded to Charles K. Kao for his theoretical work on

the single-mode optical fiber.

23

SMF has a very narrow core (typically around 9µm), which allows only single mode of light

to propagate.

Can support distances of up to several thousand kilometres, with appropriate amplification

and dispersion compensation.

Propagation of light rays can be easily understanding by the (Fig. 3.2).

Fig. 3.2: SMF [12]

It carries light pulses along single path. Only the lowest order mode (fundamental mode)

can propagate in the fiber and all higher modes are under cut-off condition.

It uses LASER as a light source. Single mode fibers are constructed by

a) Letting dimensions of core diameter be a few wavelengths

b) By having small index difference between core and cladding

In practice core-cladding index difference varies between 0.1 and 1.0 percent.

Typical single mode fibre may have a core radius of 3 microns an NA=0.1 at

wavelength= 0.8 micron.

3.2.2 Multi-Mode Fiber:

Multi-mode optical fiber is a type of optical fiber mostly used for communication over

short distances, such as within a building or on a campus. Typical multimode links have

data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters (2000 feet).The

main difference between multi-mode and single-mode optical fiber is that the former has

much larger core diameter, typically 50–100 micrometres; much larger than the

wavelength of the light carried in it. Because of the large core and also the possibility of

large numerical aperture, multi-mode fiber has higher "light-gathering" capacity than

single-mode fiber. In practical terms, the larger core size simplifies connections and also

allows the use of lower-cost electronics such as light-emitting diodes (LEDs)

and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and

1300 nm wavelength (single-mode fibers used in telecommunications typically operate at

24

1310 or 1550 nm). However, compared to single-mode fibers, the multi-mode

fiber bandwidth–distance product limit is lower. Because multi-mode fiber has a larger

core-size than single-mode fiber, it supports more than one propagation mode; hence it is

limited by modal dispersion, while single mode is not.

The LED light sources sometimes used with multi-mode fiber produce a range of

wavelengths and these each propagate at different speeds. This chromatic dispersion is

another limit to the useful length for multi-mode fiber optic cable. In contrast, the lasers

used to drive single-mode fibers produce coherent light of a single wavelength. Due to

the modal dispersion, multi-mode fiber has higher pulse spreading rates than single mode

fiber, limiting multi-mode fiber’s information transmission capacity.

Single-mode fibers are often used in high-precision scientific research because restricting

the light to only one propagation mode allows it to be focused to an intense, diffraction-

limited spot.

Jacket colour is sometimes used to distinguish multi-mode cables from single-mode ones.

The standard TIA-598C recommends, for non-military applications, the use of a yellow

jacket for single-mode fiber, and orange or aqua for multi-mode fiber, depending on

type. Some vendors use violet to distinguish higher performance OM4 communications

fiber from other types.

Fig. 3.3: MMF [10]

3.2.3 Single Mode v/s Multi-Mode:

Now, we are studying the combine behaviour of single mode and multi-mode fiber with

respect to their efficiency and ways of propagation.

25

Fig. 3.4: Light ray in SMF & MMF [9]

Typical multimode fibers have a core diameter/cladding diameter ratio of 50 microns/125

microns (10-6 meters) and 62.5/125 (although 100/140 and other sizes are sometimes used

depending on the application). Single mode fibers have a core/cladding ratio of 9/125 at

wavelengths of 1300nm and 1550nm.It is shown in (fig. 3.5)

Fig. 3.5: Core Dimension [8]

Single Mode fiber optic cable has a small diametric core that allows only one mode of light

to propagate. Because of this, the number of light reflections created as the light passes

through the core decreases, lowering attenuation and creating the ability for the signal to

26

travel further. This application is typically used in long distance, higher bandwidth runs by

Telcos, CATV companies, and Colleges and Universities.

Single Mode fiber is usually 9/125 in construction. This means that the core to cladding

diameter ratio is 9 microns to 125 microns.

Fig. 3.6: Single mode [14]

Multimode fiber optic cable has a large diametric core that allows multiple modes of light to

propagate. Because of this, the number of light reflections created as the light passes through the

core increases, creating the ability for more data to pass through at a given time. Because of the

high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced

over long distances. This application is typically used for short distance, data and audio/video

applications in LANs. RF broadband signals, such as what cable companies commonly use,

cannot be transmitted over multimode fiber.

Multimode fiber is usually 50/125 and 62.5/125 in construction. This means that the core to

cladding diameter ratio is 50 microns to 125 microns and 62.5 microns to 125 microns.

Fig. 3.7: Multimode cross section [4]

27

3.2.4 What’s Happening Inside the Multimode Fiber-

Step-Index Multimode Fiber

Due to its large core, some of the light rays that make up the digital pulse may travel a direct

route, whereas others zigzag as they bounce off the cladding. These alternate paths cause the

different groups of light rays, referred to as modes, to arrive separately at the receiving point.

The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape.

The need to leave spacing between pulses to prevent overlapping limits the amount of

information that can be sent. This type of fiber is best suited for transmission over short

distances.

Graded-Index Multimode Fiber

Contains a core in which the refractive index diminishes gradually from the centre axis out

toward the cladding. The higher refractive index at the centre makes the light rays moving down

the axis advance more slowly than those near the cladding. Due to the graded index, light in the

core curves helically rather than zigzag off the cladding, reducing its travel distance. The

shortened path and the higher speed allow light at the periphery to arrive at a receiver at about

the same time as the slow but straight rays in the core axis. The result: digital pulse suffers less

dispersion. This type of fiber is best suited for local-area networks.

3.3 Types of Optical Fiber & Colour Coding

(a) Distribution Cable:

Fig. 3.8: Distributed [16]

Distribution Cable (compact building cable) packages individual 900µm buffered fiber

reducing size and cost when compared to breakout cable. The connectors may be installed

directly on the 900µm buffered fiber at the breakout box location. The space saving

28

(OFNR) rated cable may be installed where ever breakout cable is used. FIS will

connectorize directly onto 900µm fiber or will build up ends to a 3mm jacketed fiber

before the connectors are installed.

(b) Indoor/Outdoor Tight Buffer:

Fig. 3.9: Tight buffer [16]

FIS now offers indoor/outdoor rated tight buffer cables in Riser and Plenum rated

versions. These cables are flexible, easy to handle and simple to install. Since they do not

use gel, the connectors can be terminated directly onto the fiber without difficult to use

breakout kits. This provides an easy and overall less expensive installation. (Temperature

rating -40ºC to +85ºC).

(c) Indoor/Outdoor Breakout Cable:

Fig. 3.10: Indoor breakout cable [16]

FIS indoor/outdoor rated breakout style cables are easy to install and simple to terminate

without the need for fan-out kits. These rugged and durable cables are OFNR rated so

they can be used indoors, while also having a -40c to +85c operating temperature range

and the benefits of fungus, water and UV protection making them perfect for outdoor

applications. They come standard with 2.5mm sub units and they are available in plenum

rated versions.

29

(d) Loose Tube Cable:

Fig. 3.11: Losse Tube [16]

Loose tube cable is designed to endure outside temperatures and high moisture

conditions. The fibers are loosely packaged in gel filled buffer tubes to repel water.

Recommended for use between buildings that are unprotected from outside elements.

Loose tube cable is restricted from inside building use, typically allowing entry not to

exceed 50 feet

(e) Aerial Cable/Self-Supporting:

Fig. 3.12: Aerial Cable [16]

Aerial cable provides ease of installation and reduces time and cost. Figure 8 cable can

easily be separated between the fiber and the messenger. Temperature range ( -55ºC to

+85ºC).

(f) Hybrid & Composite Cable:

Fig. 3.13: Composite [16]

30

Hybrid cables offer the same great benefits as our standard indoor/outdoor cables, with

the convenience of installing multimode and single mode fibers all in one pull. Our

composite cables offer optical fiber along with solid 14 gauge wires suitable for a variety

of uses including power, grounding and other electronic controls.

(g) Armoured Cable:

Fig. 3.14: Armoured cable [16]

Armoured cable can be used for rodent protection in direct burial if required. This cable

is non-gel filled and can also be used in aerial applications. The armour can be removed

leaving the inner cable suitable for any indoor/outdoor use. (Temperature rating -40ºC to

+85ºC).

Colour Coding:

The type of fiber can be identified by use the of standardized colours on the outer jacket. As

shown in the given Table 3.1.

Table 3.: Outer jacket colour coding [18]

Colour Fiber Type

Orange 62.5µm (OM1) or 50µm (OM2) Multi-Mode Fiber

Yellow 8-10 µm Single-Mode Fiber

Aqua 10 Gbps + 50µm (OM3) Multi-Mode Fiber

Blue Polarization maintaining Single Mode Fiber

31

Now to define the position of further fiber hair, there is an another colour code for the

positioning of fiber. As shown in the table 3.2.

Table 3.2: Fiber positioning colour coding [18]

Position Number Colour Mode

1 Blue

2 Orange

3 Green

4 Brown

5 Slate

6 White

7 Red

8 Black

9 Yellow

10 Violet

11 Rose

12 Aqua

13 through 24 Repeat colours 1 through 12

with black tracer

32

CHAPTER 4

OPTICAL NETWORKS

4.1 Passive Optical Networks

Passive Optical Network (PON) is a telecommunications technology that implements a point-

to-multipoint architecture, in which unpowered fiber Optic Splitters are used to enable a

single optical fiber to serve multiple end-points such as customers, without having to provision

individual fibers between the hub and customer.

Fig. 4.1: PON Network [14]

A PON consists of an optical line terminal (OLT) at the service provider's central office (hub)

and a number of optical network units (ONUs) or Optical Network Terminals (ONTs), near end

users. A PON reduces the amount of fiber and central office equipment required compared

with point-to-point architectures. A passive optical network is a form of fiber-optic access

network. In most cases, downstream signals are broadcast to all premises sharing multiple

fibers. Encryption can prevent eavesdropping. Upstream signals are combined using a multiple

access protocol, usually time division multiple access (TDMA). PON can be divided into

following types –

33

4.1.1 FTTH:

FTTH (fiber-to-the-home): It is a form of fiber-optic communication delivery that reaches one

living or working space. The fiber extends from the central office to the subscriber's living or

working space. Once at the subscriber's living or working space, the signal may be conveyed

throughout the space using any means, including twisted pair, coaxial cable, wireless, power line

communication or optical fiber. Fiber reaches the boundary of the living space, such as a box on

the outside wall of a home. Passive optical networks and point-to-point Ethernet are architectures

that deliver triple-play services over FTTH networks directly from an operator's central office.

Each subscriber is connected by a dedicated fibre to a port on the equipment in the POP, or to the

passive optical splitter, using shared feeder fibre to the POP and 100BASE-BX10 or 1000BASE-

BX10 transmission for Ethernet technology or GPON (EPON) technology in case of point-to-

multipoint topology.

Connectivity via FTTH:

BSNL will extend fiber from its nearest Central Office (CO) location directly or through

franchisee and install HONT and battery backup at the customers identified locations. The

services such as Voice, Broadband, and IPTV etc. will be enabled as per the customer’s request

plans for the same.

The services over FTTH:

Basic internet Access Service controlled and uncontrolled from 256Kbps to 1000Mbps.

c) TV over IP Service (MPEG2).

d) Video on Demand (VoD)(MPEG4) play like VCR

e) Audio on Demand Service

f) Bandwidth on Demand (User and or service configurable)

g) Remote Education

h) Point to Point and Point to Multi Point Video Conferencing, virtual

classroom

i) Voice and Video Telephony over IP: Connection under control of centrally

located soft switches

j) Interactive Gaming

k) VPN on broadband

l) Dial up VPN Service

m) Virtual Private LAN Service (VPLS)

4.1.2 FTTC:

FTTC (fiber to the curb): where fiber is generally too far from the users for standard ethernet

configurations over existing copper cabling. They generally use very-high-bit-rate digital

subscriber line (VDSL) at downstream rates of 80 Mbit/s, but this falls extremely quickly over

34

a distance of 100 meters. Fiber is often said to be "future-proof" because the data rate of the

connection is usually limited by the terminal equipment rather than the fiber, permitting

substantial speed improvements by equipment upgrades before the fiber itself must be upgraded.

Still, the type and length of employed fibers chosen, e.g. multimode vs. single-mode, are critical

for applicability for future connections of over 1 Gbit/s.

4.1.3 FTTP:

FTTP (fiber-to-the-premises): This term is used either as a blanket term for both FTTH and

FTTB, or where the fiber network includes both homes and small businesses. Fiber to the

premises (FTTP) is a form of fiber-optic communication delivery, in which an optical fiber is run

in an optical distribution network from the central office all the way to the premises occupied by

the subscriber. The term "FTTP" has become ambiguous and may also refer to FTTC where the

fiber terminates at a utility pole without reaching the premises.

4.1.4 FTTDp:

Fiber to the Distribution Point (FTTDp)–this solution has been proposed in the last two years.

Connecting the POP to the Distribution Point via the optical cable and then from the Distribution

Point to the end-user premises via existing copper infrastructure. The Distribution Points could

be a hand-hole, a drop box on the pole or located in the basement of a building. This architecture

could support VDSL or G. Fast technology for a short last mile, normally less than 250m.

Fig. 4.2: FTTx Comparison [12]

35

Optical Fiber in India:

Fiber to the Home (FTTH) is a unique technology being used by BSNL for the first time in

India. The fiber connectivity having unlimited bandwidth and state of the art technology

provides fix access platform to deliver the high speed broadband from 256 Kbps to 100 Mbps,

IPTV having different type of contents like HDTV and future coming 3D TV and range of voice

telephony services. It provides a comprehensive solution for the IP leased line, internet, Closed

User Group (CUG), MPLS-VPN, VoIP, video conferencing, video calls, etc. Whatever the

services available on the internet platform, bandwidth on demand can be delivered by this

connectivity to the without changing the access fiber and home device. Customer will get a CPE

called Home Optical Network Termination (HONT) consist of 4X100 Mbps Ethernet ports and 2

normal telephone ports. Each 100 Mbps ports will provide broadband, IPTVs, IP Video call and

leased line etc. as required by the customers. Customer will get power back unit having full load

backup of four hours and normal backup of three days. This power backup will be AC input and

connecting to the HONT on 12V DC.

4.2 Synchronous Optical Network (SONET)

4.2.1 SONET/SDH Protocol Overview:

Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are

standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber

using lasers or light-emitting diodes (LEDs). Lower data rates can also be transferred via an

electrical interface. The method was developed to replace the Plesiochronous Digital Hierarchy

(PDH) system for transporting larger amounts of telephone calls and data traffic over the same

fiber without synchronization problems. SONET generic criteria are detailed in Telcordia

Technologies Generic Requirements document GR-253-CORE.Generic criteria applicable to

SONET and other transmission systems (e.g., asynchronous fiber optic systems or digital radio

systems) are found in Telcordia GR-499-CORE.

SONET and SDH often use different terms to describe identical features or functions. This can

cause confusion and exaggerate their differences. With a few exceptions, SDH can be thought of

as a superset of SONET. The protocol is an extremely heavily-multiplexed structure, with the

header interleaved between the data in a complex way. This permits the encapsulated data to

have its own frame rate and be able to "float around" relative to the SDH/SONET frame structure

and rate. This interleaving permits a very low latency for the encapsulated data. Data passing

through equipment can be delayed by at most 32 microseconds (µs), compared to a frame rate of

125 µs; many competing protocols buffer the data during such transits for at least one frame or

packet before sending it on. Extra padding is allowed for the multiplexed data to move within the

overall framing, as the data is clocked at a different rate than the frame rate. The protocol is

36

made more complex by the decision to permit this padding at most levels of the multiplexing

structure, but it improves all-around performance.

Fig. 4.3: Sonet Ring [15]

4.2.2 SONET Multiplexing:

The multiplexing principles of SONET are as follows-

Mapping: It is used when tributaries are adapted into VTs by adding justification bits and POH

information.

Aligning: It takes place when a pointer is included in STS path or VT POH, to allow the first

byte of VT to be located.

Multiplexing: Used when multiple order lower path-layer signals are adapted into a higher

order- path signal or vice-versa.

Stuffing: SONET has ability to handle various input tributary rates from asynchronous signals;

as the tributary signals are multiplexed and aligned, some spare capacity has been designed into

the SONET frame to provide enough space for all these various tributary rates; therefore, at

certain point in multiplexing hierarchy, this space capacity is filled with fixed stuffing bits that

carry no information but are required to fill up the particular frame.

One of the benefits of SONET is that it can carry large payloads (50 Mbps). However, the

existing digital hierarchy signals can be accommodated as well, thus protecting investment in

current equipment.

Figure 4.4 illustrates the basic multiplexing structure of SONET. Any type of services, ranging

from voice to high-speed data and video, can be accepted by various types of service adapters.

37

Fig. 4.4: Sonet Multiplexing Hierarchy [7]

4.2.3 Benefits of SONET:

Today's carrier backbone networks are supported by synchronous optical network (SONET)

and synchronous digital hierarchy (SDH) transmission technologies. SONET is the standard

used in the United States and SDH is the standard used outside the United States.

SONET/SDH specification outlines the frame format, multiplexing method, and

synchronization method between the equipment, as well as the specifying optical interface.

SONET/SDH will continue to play a key role in the next generation of networks for many

carriers. In the core network, the carriers offer services such as telephone, dedicated leased

lines, and Internet protocol (IP) data, which are continuously transmitted. The individual data

is not transmitted on separate lines; instead it is multiplexed into higher speeds and

transmitted on SONET/SDH networks at up to 10 gigabits per second (Gbps). The following

sections describe the need for SONET/SDH.

Synchronous Digital Transmission

Until the introduction of SONET in the mid-1980s, plesiochronous digital hierarchy (PDH)

systems commonly used data multiplexing technology. The primary problem with PDH was

that to extract low-speed traffic, all traffic that was multiplexed to higher speeds had to be de-

multiplexed into lower speeds. With PDH, the equipment had to support multiplexing and de-

multiplexing the signal, adding cost and complexity to the network. SONET was introduced

as a synchronous transmission system that could directly extract low-speed signals from

multiplexed high-speed traffic. Based on the ANSI standard, the CCITT approved the

international standard known as SDH based on the SONET technology.

38

Mid-Span Meet

The adoption and acceptance of SONET allowed carriers to be able to choose equipment from

different vendors instead of using only a single vendor with a proprietary optical format. The

ability to mix equipment from different vendors in one system is called the "Mid-Span Meet".

Speed

SONET and SDH give carriers much more bandwidth to carry voice and data traffic than

PDH technology. The base rate for SONET is 51 Mbps. Synchronous transport signal (STS-n)

refers to the SONET signal in the electrical domain, and optical carrier (OC-n) refers to the

SONET signal in the optical domain. The base rate for SDH is 155 Mbps. Synchronous

transport module (STM-n) refers to the SDH signal level in both the electrical and optical

domains.

Reliability

Carriers require an extremely reliable network and cannot afford downtime. Therefore, most

SONET/SDH networks have a ring structure, which adds high reliability to the overall

transmission network. Even if the optical fiber is cut, the transmission path is backed-up and

restored within 50 ms. Figure 4.5 shows an example SONET ring.

Fig. 4.5: Sonet Ring [10]

A SONET/SDH transmission network is composed of several pieces of equipment, including:

(a) Terminal multiplexer (TM)

(b) Add-drop multiplexer (ADM)

(c) Repeater

(d) Digital cross-connect system (DCS)

39

Chapter 5

OPTICAL FIBER INSTALLATION

5.1 Introduction:

Fiber optic network installation refers to the specialized processes leading to a successful

installation and operation of a fiber optic network. It includes determining the type of

communication system(s) which will be carried over the network, the geographic layout

(premises, campus, outside plant (OSP, etc.), the transmission equipment required and the fiber

network over which it will operate. Next we have to consider requirements for permits,

easements, permissions and inspections. Once we get to that stage, we can consider actual

component selection, placement, installation practices, testing, troubleshooting and network

equipment installation and start-up. Finally, we have to consider documentation, maintenance

and planning for restoration in event of an outage.

5.2 Surveying & Preparing area root map:

It is the first and most significant step of optical fiber installation. Here, first a survey team is

sent to the targeted area, where they do a survey on number of customers interested and how the

fibre will be laid. The task of the optical engineer is to draw a root map according to the

requirement, in such way that minimum of resources used. Then the engineer makes a rough

sketch of fibre laying root, and then sent it to service division for other formalities.

Fig. 5.1: Google street view [18]

40

Whether a network is planned for an area with a high or a low population density the approach

will be a completely different exercise as the optimal architecture and design rules for these

networks will differ greatly:

• In a dense area, one provider will choose to group more subscribers on a single aggregation

point and achieve a relatively good filling of all aggregation points; however in rural areas

distance between buildings and aggregation points may become a more important constraint in

the design than capacity of each aggregation point, resulting in a broader variation in filling of

aggregation points.

• In dense areas there are, in general, more equivalent options for grouping buildings around

aggregation points, as well as for routing the cables between aggregation points and buildings. In

rural areas there are less equivalent alternatives.

• Rural areas will have more options for placing cabinets, while urban areas spaces are limited

and thus more constraints apply for cabinet placement.

• Unit costs for deploying cables can differ significantly between urban and rural areas: in rural

areas, one meter of trenching will be less expensive than similar trenching in urban areas, as, for

example, the type of pavement in the two areas differs as does the associated cost of restoring the

individual pavements. Additionally, more aerial deployments are used in rural areas. This will

impact on the relationship between labour and material costs of both types of deployment, thus

requiring a different set of design rules to be used for achieving minimal costs

• Equipment vendors have developed special deployment methods and cable types for urban

versus rural deployments.

Regarding route information, a minimal input is the street topology information. This data is

available for most areas. Typical data providers for street topologies are the providers of large

geographical information systems (GIS) databases that are also used for car navigation systems.

This data is often displayed on mapping and route planning websites such as

http://maps.google.com. Alternative local data providers may exist. For some regions, the open

source data from OpenStreetMap, www.openstreetmap.org may be a good starting point.

Fig. 5.2: Satellite view [18]

41

5.3 Trenching:

A trench is a type of excavation or depression in the ground that is generally deeper than it is

wide (as opposed to a wider gully, or ditch), and narrow compared to its length.

The advantages of this technique over conventional cable laying technologies lie essentially

in its speed of execution, lower cost, significantly lower environmental impact and limited

disruption to road traffic and, as a consequence of the previous items, easiness in obtaining

permits for the taking over of public area.

Trenching can be carried out by two methods either by labour workers as per the route plan

requirements and site terrain or by a machine known as trencher. A trencher is a piece

of construction equipment used to dig trenches, especially for laying pipes or cables, for

installing drainage, or in preparation for trench warfare. Trenchers may range in size from

walk-behind models, to attachments for a skid loader or tractor, to very heavy tracked heavy

equipment.

Fig. 5.3: Fiber Laying [19]

After trenching, the next step is laying of duct in trench. Duct is that pipe in which fibre cables

are going to blow. They are made up of hard plastic. The another method of laying duct is

through HDD.

HDD: HDD stands for Horizontal Directional Drilling; it is used to lay duct without trenching

the ground. It has a flexible drilling bid which drills underground up to 1-3 Km. It is a steerable

trenchless method of installing underground pipe, conduit, or cable in a shallow arc along a

prescribed bore path by using a surface-launched drilling rig, with minimal impact on the

surrounding area.

42

Fig. 5.4: HDD working [17]

5.4 Cable Jetting:

Cable Pulling is the traditional method of pulling cables through previously installed cable ducts

or conduit using a pull line. Successful pulling requires cables to be pulled at the straightest

angles possible. The fewer bends that the cable needs to be pulled through — the better. A

generous amount of Cable Pulling Lubricant should also be used during the entire process to

decrease friction and avoid damaging the cable. Clear communication between installation team

members is also essential when pulling cable. The technique of installing flexible and

lightweight fibre optic units using compressed air was developed during the 1980s by British

Telecom. This early version of jetting did not use additional pushing. True cable jetting was

invented by Willem Griffioen of KPN Research in the late 1980s. Cable jetting is the process of

blowing a cable through a duct while simultaneously pushing the cable into the duct.

Compressed air is injected at the duct inlet and flows through the duct and along the cable at high

speed.

Cable jetting is the process of blowing a cable through a duct while simultaneously pushing the

cable into the duct. Compressed air is injected at the duct inlet and flows through the duct and

along the cable at high speed. (Preferably, no suction pig is used at the cable head.) The high

speed air propels the cable due to drag forces and pressure drop. The friction of the cable against

the duct is reduced by the distributed airflow, and large forces that would generate high friction

are avoided. Because of the expanding airflow, the air propelling forces are relatively small at

the cable inlet and large at the air exhaust end of the duct. To compensate for this, an additional

pushing force is applied to the cable by the jetting equipment. The pushing force, acting mainly

near the cable inlet, combined with the airflow propelling forces, increases the maximum jetting

distance considerably. Special lubricants have been developed for cable jetting to further reduce

friction.

43

Fig. 5.5: Cable jetting techniques [17]

The advantages of cable jetting over cable pulling include:

(a) Longer installation distances possible

(b) Bends in duct don’t hinder jetting process

(c) Less force is exerted on the cable

(d) No need to install a winch rope

(e) Equipment only needed at one end of route

44

Chapter 6

SPLICING OF OPTICAL FIBER

6.1 Introduction

The essential requirements for establishing a low-loss and high-speed telecommunication line

using optical fibers are high performance and quality splicing technology. The simple connection

of optical fibers using optical connectors and mechanical splices is increasing. Fiber optic

splicing involves joining two fiber optic cables together. The other, more common, method of

joining fibers is called termination or connectorization. Fiber splicing typically results in lower

light loss and back reflection than termination making it the preferred method when the cable

runs are too long for a single length of fiber or when joining two different types of cable

together, such as a 48-fiber cable to four 12-fiber cables. Splicing is also used to restore fiber

optic cables when a buried cable is accidentally severed.

There are two methods of fiber optic splicing,

(a) Fusion splicing

(b) Mechanical splicing

6.2 Fusion Splicing

Fusion splice is needed for long-haul and high-capacity trunk communications such as submarine

optical fiber cable. This requires not only ultra-low loss and low back reflection, but also long

term reliability and strength of the fusion splice. The fusion splice is also used when splicing

specialty optical fibers for light amplification and high power laser transmission for use in

various medical procedures or machining applications. In addition to the splicing technology,

fiber cleaving and splice protection technologies are also important steps in the splicing process.

Fusion splicing is the process of fusing or welding two fibers together usually by an electric arc.

Fusion splicing is the most widely used method of splicing as it provides for the lowest loss and

least reflectance, as well as providing the strongest and most reliable joint between two fibers.

Fusion splicing may be done one fiber at a time or a complete fiber ribbon from ribbon cable at

one time. First we'll look at single fiber splicing and then ribbon splicing. Fusion splicing

machines are mostly automated tools that require you pre-set the splicing parameters or choose

factory recommended settings that will control the splicing process itself. 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.

45

The major steps involved in optical fiber fusion splicing can be summarized as the following.

a) Optical fiber stripping: The fiber cable jacket is removed and then the fiber polymer coating

is stripped with fiber optic strippers.

b) Fiber cleaving: The fiber is cleaved with specialized tool called fiber cleaver. Two types of

fiber cleaver exist: high precision fiber cleaver for single mode applications and field cleaver for

multimode applications. A mirror like almost perfect end face is achieved by this cleaving

process.

c) Fiber alignment: The fibers are laterally aligned to each other by step motor in a fusion

splicer. This may involve rotating the fibers in polarization maintaining fiber splicing.

d) Fiber welding: The fibers are then heated with electric arc or other methods to the fiber

glass's softening point and then both fibers are pressed together to form a solid joint.

e) Insertion loss estimation: The insertion loss is estimated based on the fusion quality and

dimensions.

f) Pull tension strength testing: The fusion is pull proof tested when opening the fusion splicer

cover.

g) Splice protection with fusion splice sleeve: The fusion splice joint is then protected with a

heat shrink tube with a steel strength member inside to form a solid and reliable fiber joint.

Fig. 6.1: Fusion electric arc [9]

46

Fig. 6.2: Optical cleaver [9] Fig. 6.3: Strippers [6]

Optical fiber applications have expanded to many fields other than telecommunications. We

developed a specialty fiber fusion splicer that has an adjustable fiber clamping position

mechanism, electrode oscillating mechanism, and optical fiber end-view image observation

system in order to splice various types, such as polarization maintaining fibers and large

diameter fibers for high power laser transmission. Fig.6.4 shows the appearance of this splicer.

Fig. 6.4: Fusion splice [20]

47

The Advantages of Optical Fiber Fusion Splicing

There are other approaches for interconnecting fibers such as fiber optic connectors and

mechanical splicing. Compared to these two, fusion splicing has many advantages as explained

below.

(a) Fusion splicing is very compact

(b) Fusion splicing has the lowest insertion loss

(c) Fusion splicing has the lowest back reflection (optical return loss ORL)

(d) Fusion splicing has the highest mechanical strength

(e) Fusion splicing is permanent

(f) Fusion splicing can withstand extreme high temperature changes

(g) Fusion splicing prevents dust and other contaminants from entering the

optical path

6.3 Mechanical Splicing

Mechanical splices are used to create permanent joints between two fibers by holding the fibers

in an alignment fixture and reducing loss and reflectance with a transparent gel or optical

adhesive between the fibers that matches the optical properties of the glass. Mechanical splices

generally have higher loss and greater reflectance than fusion splices, and because the fibers are

crimped to hold them in place, do not have as good fiber retention or pull-out strength. The

splice component itself, which includes a precision alignment mechanism, is more expensive

than the simple protection sleeve needed by a fusion splice.

Mechanical splices are most popular for fast, temporary restoration or for splicing multimode

fibers in a premises installation. They are also used - without crimping the fibers - as temporary

splices for testing bare fibers with OTDRs or OLTSs. Of course most pre-polished splice

connectors use an internal mechanical splice (several actually have fusion splices) so the

mechanisms and techniques described here apply to those also.

The advantage of mechanical splices is they do not need an expensive machine to make the

splices. A relatively simple cleaver and some cable preparation tools are all that's needed,

although a visual fault locator (VFL) is useful to optimize some types of splices.

48

Fig. 6.5: Mechanical splice equipment [23]

What Is Mechanical Fiber Splice?

Fiber optic mechanical splice performs a similar function to the fusion splice except that the

fibers are held together by mechanical means rather than by a welding technique. Mechanical

splices somewhat look like fusion splice protection sleeves. In a mechanical splice, two cleaved

fiber tips are mechanically aligned to each other by a special housing. Usually, index matching

gel is positioned between the fiber tips to maximize coupling and minimize back reflection.

Advantages of Mechanical Splice

There are some significant advantages of using mechanical fiber splice than fusion splices. Here

are a few of them:

(a) Mechanical splices require no power supplies

(b) Many mechanical fiber splice designs require no extra tools beyond a fiber stripper and

fiber cleaver

(c) They can be used in situations where fusion splicing is not practical or impossible

(d) Mechanical splices can be made within a couple of minutes, this makes it ideal for

temporary connections

Disadvantages of Mechanical Fiber Splices

Fiber optic mechanical splices have their cons too.

(a) Higher insertion loss. The typical insertion loss for a mechanical splice is about 0.2dB

which is significantly higher than the 0.02dB loss for a typical fusion splice.

49

(b) Mechanical splices are typically for multimode fibers. The tough alignment tolerance for

single mode fibers makes it hard for mechanical splices to meet

(c) Mechanical splice is more expensive than fusion splices. But if you take into account the

expensive fusion splicing machines that fusion splices need, the average cost is actually

much lower for mechanical splice if you just do a few splices.

(d) Since the refractive index of most index matching compounds varies with temperature, so

the optical performance of a mechanical splice can be sensitive to ambient temperature

(e) Mechanical splices are not thought to be as reliable as fusion splices over long periods of

time

(f) Mechanical splices are used only in relatively benign environments such as inside an

office building.

Alignment Mechanisms of Mechanical Fiber Optic Splices

The principle of mechanical splice is simple and straightforward. Two fibers are stripped,

cleaned and cleaved. They are then aligned and held in position either by epoxy resin or by

mechanical clips.

1. V-Groove Type

V-groove has been used widely in aligning optical fibers. The most obvious example is

its success in fusion splicing machines. Look at the following illustration (Fig. 6.6).

Fig. 6.6: V-Groove picture [14]

50

V-groove is the most commonly used alignment mechanism for mechanical fiber splices.

V-groove consists of a base plate in which a precise V-groove is etched.

(a) Cleaved fibers are placed into the groove and their ends are butt-coupled into

contact.

(b) Index matching gel is used to bridge the gap between the two ends to prevent gap

loss and to reduce Fresnel reflection

(c) A locking mechanism then holds the fibers in position and provides mechanical

protection for the fibers

(d) Index matching epoxy can be used in place of index matching gel. The epoxy is

usually cured with ultraviolet light. The epoxy can hold the fibers in place

2. Bent Tube Type

Bent tube design actually uses the same principle as V-groove. A length of fiber is pushed into

a tube which is curved, the springiness of the fiber forces itself to follow the outside of the

curve. If the tube is of square cross-section, the fiber will follow the far corner. The fiber is

now positioned by a V-shaped wall of the tube. In some designs, the cross-section of the bent

tube is circular instead of square. Index matching gel is added before the fibers are inserted.

Fig. 6.6: Bent tube [20]

51

3. Precision Tube Type

The precision tube type is very simple and straightforward. A precise hole with a slightly

larger diameter than the fiber OD is formed through a piece of ceramic or other material.

When a piece of bare fiber is inserted from each end, the two fibers are aligned when they

contact.

The disadvantage of this type is that insertion loss is higher than other types. This is caused by

the hard to control tolerance of the hole diameter.

6.4 Fusion v/s Mechanical Splicing:

Mechanical and fusion splicing both accomplish the same thing; they bring two optical

fibres together and hold them that way so that an optical signal can pass through the join.

However, this is where the similarities end--and, for contractors, where weighing trade-offs

begins. Overall, the advantages of fusion splicing are primarily lower loss and better

reflectance performance; it is in these areas that it surpasses mechanical splicing.

In the early days of fiber optics, fusion splicing was an exacting, demanding task. Today -

although care is needed - the splicing procedure is straightforward, with key steps fully

automated. Mechanical and fusion splicing are two broad categories that describe the

techniques used for fiber splicing. A Mechanical Splice is a fiber splice where mechanical

fixtures and materials perform fiber alignment and connection. A fusion splice is a process

of using localized heat to melt or fuse the ends of two optical fibers together. Each splicing

technique seeks to optimize splice performance and reduce splice loss. Low-loss fiber

splicing results from proper fiber end preparation and alignment. Mechanical splices have

higher insertion losses, lower reliability and higher return losses than fusion splicing.

Table 6.1: Comparison between fusion & mechanical splicing [16]

Sr. No. Fusion Splicing Mechanical Splicing

1. Two fibre end are aligned and then

fused together.

Just a mechanical alignment device.

2. Fused with the help of electric arc. Splice with the help of index

matching gel.

3. Still, two separated fibres are not

continuous.

The joint is continuous.

5. Due to electric arc, the strength of

glass core is weaken at the point of

splicing, which cause losses.

No such problem is encountered in

mechanical splicing.

52

Chapter 7

POWER MEASUREMENT

7.1 Introduction

Ideally, optical signals coupled between fiber optic components are transmitted with no loss of

light. However, there is always some type of imperfection present at fiber optic connections that

causes some loss of light. It is the amount of optical power lost at fiber optic connections that is a

concern of system designers. The design of fiber optic systems depends on how much light is

launched into an optical fiber from an optical source and how much light is coupled between

fiber optic components, such as from one fiber to another. The amount of power launched from a

source into a fiber depends on the optical properties of both the source and the fiber. The amount

of optical power launched into an optical fiber depends on the radiance of the optical source. An

optical source's radiance, or brightness, is a measure of its optical power launching capability.

Radiance is the amount of optical power emitted in a specific direction per unit time by a unit

area of emitting surface. For most types of optical sources, only a fraction of the power emitted

by the source is launched into the optical fiber. The loss in optical power through a connection is

defined similarly to that of signal attenuation through a fiber. Various types of loss are occur in

optical fiber communication, which are as follows-

7.2 Types of Power losses

7.2.1 Extrinsic Loss:

These losses are specific to geometry and handling of the fibers and are not functions of the

fiber material itself. There are three basic types:

(a) bending losses

(b) launching losses

(c) connector losses

(a) Bending Losses: Bending losses are the result of distortion of the fiber from the ideal

straight-line configuration. While the light is traveling inside the fiber, part of the wave

front on the outside of the bend must travel faster than the part of the smaller inner radius

of the bend. Since this is not possible, a portion of the wave must be radiated away.

Losses are greater for bends with smaller radii, particularly for kinks or micro-bends in a

fiber. An important cause of attenuation is due to micro-bending of the fiber. Micro-

bending is due to irregularly distributed undulations in the fiber with radii of curvature of

a few millimetres and deviations from the mean line of a few micrometres, as

exemplified in Figure 7.1

53

Fig. 7.1: Bending loss [5]

(b) Launching Losses: The term launching loss refers to an optical fiber not being able to

propagate all the incoming light rays from an optical source. These occur during the

process of coupling light into the fiber (e.g., losses at the interface stages). Rays launched

outside the angle of acceptance excite only dissipative radiation modes in the fiber. In

general, elaborate techniques have been developed to realize efficient coupling between

the light source and the fiber, mainly achieved by means of condensers and focusing

lenses. The focused input beam of light needs to be carefully matched by fiber parameters

for good coupling. Equally, once the light is transmitted through the fiber, output fiber

characteristics must also match the output target characteristics to be able to couple the

largest proportion of the transmitted light. This can be done by a suitable focusing lens

arrangements in the output end.

(c) Connector Losses: Connector losses are associated with the coupling of the output of

one fiber with the input of another fiber, or couplings with detectors or other components.

The significant losses may arise in fiber connectors and splices of the cores of the joined

fibers having unequal diameters or misaligned centres, or if their axes are tilted.

Fig. 7.2: Connector Loss [24]

54

In general, the positions and shapes of the fiber cores are controlled to tight manufacturing

tolerances. Fibers having attenuations greater than 1 dB/km are rarely used in communication

networks. Nevertheless, the attenuation of badly matched fibers may exceed 1 dB/km per

connector or splice if they are badly handled during installation stages. A good coupling

efficiency requires precise positioning of the fibers to centre the cores. The simplest way to avoid

connector losses is by splicing the two ends of the fibers permanently, either by gluing of by

fusing at high temperatures. Losses in gaps can be viewed as a type of Fresnel loss because

existing air space introduces two media interfaces and their associated Fresnel reflection losses.

In this case, there are two major losses to be considered. The first loss takes place in the inner

surface of the transmitting fiber, and the second loss occurs due to reflections from the surface of

the second fiber. One way of eliminating these losses is by introducing a coupler that matches

the optical impedances of the two materials. This arrangement results in matched reflection

coefficients, which is analogous to matching of impedances.

7.2.2 Intrinsic Fiber Losses

Intrinsic fiber losses are those associated with the fiber optic material itself, and the total loss is

proportional to length L. Once inside the fiber, light is attenuated primarily because of absorption

and scattering; therefore, these are the primary causes of the losses.

(a) Absorption Losses: As in the case of most transitive systems, light loss through

absorption in an optical fiber tends to be an exponential function of length. Absorption

loss is caused by the presence of impurities such as traces of metal ions (e.g., Cu2+,

Fe3+) and hydroxyl (OH–) ions. Optical power is absorbed in the excitation of molecular

vibrations of such impurities in the glass, as illustrated in Figure 59.3. One characteristic

of absorption is that it occurs only in the vicinity of definite wavelengths corresponding

to the natural oscillation frequencies or their harmonics of the particular material. In

modern fibers, absorption losses are almost entirely due to OH–1 ion. The fundamental

vibration mode of these ions corresponds to l = 2.73 µm and the harmonics at 1.37 and

0.95 µm. It is possible to employ dehydration techniques during manufacturing to reduce

presence of OH1 ions. Unlike scattering losses, which are relatively wideband effects,

absorption losses due to each type of impurity act like a band-suppression filter, showing

peak absorption at well-defined wavelengths.

(b) Scattering Losses: Despite the careful manufacturing techniques, most fibers are

inhomogeneous that have disordered, amorphous structures. Power losses due to

scattering are caused by such imperfections in the core material and irregularities

between the junction and cladding in structural in homogeneities, the basic molecular

structure has random components, whereas, in compositional inhomogeneity, the

chemical composition of the material varies. The net effect from either inhomogeneity is

a fluctuation in the refractive index. As a rule of thumb, if the scale of these fluctuations

is on the order of l/10 or less, each irregularity acts as a scattering centre. This is a form

of Rayleigh scattering and is characterized by an effective absorption coefficient that is

proportional to. Rayleigh scattering can be caused by the existence of tiny dielectric

55

inconsistencies in the glass. Because these perturbations are small with respect to the

waves being propagated, light striking a Rayleigh imperfection scatters in all directions.

Scattering losses are less at longer wavelengths, where the majority of the transmission

losses are due to absorption from impurities such as ions. Rayleigh scattering losses are

not localized, and they follow a distribution law throughout the fiber. However, they can

be minimized by having low thermodynamic density fluctuations. A small part of the

scattered light may scatter backward, propagating in the opposite direction. This

backscattering has important characteristics and may be used for measuring fiber

properties. Usually, the in homogeneities in the glass are smaller than the wavelength l of

the light. The scattering losses in glass fibers approximately follow the Raleigh scattering

law; that is, they are very high for small wavelengths and decrease with increasing

wavelength.

(c) Linear scattering losses: Through this mechanism a portion/total optical power within

one propagating mode is transferred to another. Now when the transfer takes place to a

leaky or radiation mode then the result is attenuation. It can be divided into two major

categories namely- Mie scattering and Rayleigh scattering.

(i) Mie Scattering: Non perfect cylindrical structure of the fiber and imperfections like

irregularities in the core-cladding interface, diameter fluctuations, strains and bubbles

may create linear scattering which is termed as Mie scattering.

(ii) Rayleigh Scattering: The dominant reason behind Rayleigh scattering is refractive

index fluctuations due to density and compositional variation in the core. It is the

major intrinsic loss mechanism in the low impedance window. Rayleigh scattering

can be reduced to a large extent by using longest possible wavelength.

(d) Nonlinear scattering losses: Specially at high optical power levels scattering causes

disproportionate attenuation, due to nonlinear behaviour. Because of this nonlinear

scattering the optical power from one mode is transferred in either the forward or

backward direction to the same, or other modes, at different frequencies. The two

dominant types of nonlinear scattering are:

(i) Stimulated Brillouin Scattering and

(ii) Stimulated Raman Scattering

7.3 Power Loss Measurement

The most basic fiber optic measurement is optical power from the end of a fiber. This

measurement is the basis for loss measurements as well as the power from a source or presented

at a receiver. Typically, both transmitters and receivers have receptacles for fiber optic

connectors, so measuring the power of a transmitter is done by attaching a test cable to the

source and measuring the power at the other end. For receivers, one disconnects the cable

attached to the receiver receptacle and measures the output with the meter.

56

Fig. 7.3: Power Measurement [22]

While optical power meters are the primary power measurement instrument, optical time

domain reflectometers (OTDRs) also measure power in testing loss.

Optical power is based on the heating power of the light, and some optical lab instruments

actually measure the heat when light is absorbed in a detector. While this may work for high

power lasers, these detectors are not sensitive enough for the low power levels typical for

fiber optic communication systems.

7.3.1 Power Meter:

An optical power meter (OPM) is a device used to measure the power in an optical signal.

The term usually refers to a device for testing average power in fiber optic systems. Other

general purpose light power measuring devices are usually

called radiometers, photometers, laser power meters (can be photodiode sensors

or thermopile laser sensors), light meters or lux meters. A typical optical power meter

consists of a calibrated sensor, measuring amplifier and display. The sensor primarily

consists of a photodiode selected for the appropriate range of wavelengths and power levels.

On the display unit, the measured optical power and set wavelength is displayed. Power

meters are calibrated using a traceable calibration standard such as a NIST standard. A

traditional optical power meter responds to a broad spectrum of light, however the calibration

is wavelength dependent. This is not normally an issue, since the test wavelength is usually

known, however it has a couple of drawbacks. The most basic fiber optic measurement is

optical power from the end of a fiber. This measurement is the basis for loss measurements

as well as the power from a source or presented at a receiver.

57

Measurement of the power of a transmitter is done by attaching a test cable to the source and

measuring the power at the other end. For receivers, one disconnects the cable attached to the

receiver receptacle and measures the output with the meter. Optical power meters typically

use semiconductor detectors since they are sensitive to light in the wavelengths and power

levels common to fiber optics. Most fiber optic power meters are available with a choice of 3

different detectors, silicon (Si), Germanium (Ge), or Indium-Gallium-Arsenide (In GaAs).

Fig. 7.4: Power Meter [16]

7.3.2 OTDR:

The OTDR is the most important investigation tool for optical fibres, which is applicable for

the measurement of fibre loss, connector loss and for the determination of the exact place and

the value of cable discontinuities. By means of very short pulses it is also possible to

measure the modal dispersion of multimodal fibres. The structure of a typical OTDR

equipment is shown below:

58

Fig. 7.5: OTDR [16]

The principal of the OTDR analyser is the following: a short light pulse is transmitted into

the fibre under test and the time of the incidence and the amplitude of the reflected pulses are

measured. The commonly used pulse width ranges from nanosecs to microsecs, the power of

the pulse can exceed 10 mW. The repetition frequency depends on the fibre length, typically

is between 1 and 20 kHz, naturally it is smaller for longer fibres. The division by 2 at the

inputs of oscilloscope is needed since both the vertical (loss) and the horizontal (length)

scales correspond to the one-way length.

Some of the terms often used in specifying the quality of an OTDR are as follows:

Accuracy: Defined as the correctness of the measurement i.e., the difference between the

measured value and the true value of the event being measured.

Measurement range: Defined as the maximum attenuation that can be placed between

the instrument and the event being measured, for which the instrument will still be able to

measure the event within acceptable accuracy limits.

Instrument resolution: Is a measure of how close two events can be spaced and still be

recognized as two separate events. The duration of the measurement pulse and the data

sampling interval create a resolution limitation for OTDRs. The shorter the pulse duration

and the shorter the data sampling interval, the better the instrument resolution, but the

shorter the measurement range. Resolution is also often limited when powerful

reflections return to the OTDR and temporarily overload the detector. When this occurs,

sometime is required before the instrument can resolve a second fiber event. Some OTDR

manufacturers use a “masking” procedure to improve resolution. The procedure shields

or “masks” the detector from high-power fiber reflections, preventing detector overload

and eliminating the need for detector recovery.

59

CHAPTER 8

CONCLUSION

In present era, the communication sector is at its peak. But, it is yet farther to go. Today

communication is not only limited to voice and data, rather we have broken the data barrier.

I had an excellent experience during my training at AKSH OPTIFIBRE LTD. I learned about

Optical fiber installation. AKSH is the only IPTV service provider in Rajasthan. AKSH holds a

reputation of being the pioneer in manufacturing of raw materials for optical fibre cables and is

globally renowned for high quality FRP (Fibre reinforced plastic) Rods, ARP (Aramid reinforced

plastic) rods and WS yarn (water blocking yarn) that gives the best reinforcement and strength to

Optical Fibre Cables.

I was working as Optical Fiber Technician Trainee during my training. First 7 days we have

taught some basics terminologies realted to optical fiber communication and some basic

operations which we have to perform on site with the team. The class were conducted at service

division of AKSH at Sitapura, Jaipur. Then after a week we have allotted to different teams for

an onsite experience of Optical fiber installation and splicing of various types of optical fibers.

Overall the learning environment was very good and I have learned various terminologies related

to optical fiber communication and also gain some tremendous practical field experience.

60

CHAPTER 9

REFERENCES

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379–423, 623–656, 1948.

[3] Jian Chao Li & Dennis R. Alexander, “Propagation of ultra-short laser pulses through

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[5] X. Wang and K. Kitayama, "Analysis of beat noise in coherent and incoherent time-preading

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[12] G. Keiser, op cit, p 51

[13] Franz Fidler, Markus Knapek, Joachim Horwath, and Walter R.Leeb, “Optical

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Lett.31, 380, 1995.

[15] Mizushima et al., “Improving Performance and Tolerance in Harsh Environmental

Conditions of New Fusion Splicer”, Fujikura Technical Review, Vol114, pp.17-20, 2008

[16] Iwashita et al., “Small Fusion Splicer Splice MateTM”, Fujikura Technical Review, Voll08,

pp.10-13, 2005.

[17] Tobita et al., “Specialty Fiber Fusion Splicer”, Fujikura Technical Review, Vol119, pp.17-

21, 2010

[18] Konuma et al., “Fusion Splicer for Specialty Optical Fiber with Advanced Functions”,

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[20] http://www.thefoa.org/tech/ref/termination/mechsplice.html

[21] http://www.timbercon.com/medical-fiber-optics/

[22] http://www.fibersystems.com/products/navy/

[23] http://www.ratioplast.com/pdf/rpo/909/E09PM00000111_RevA01.pdf

[24] http://www.akshoptifibre.com/infrastructure.php