WIDEBAND OPTICAL AMPLIFIER USING HIGH CONCENTRATION

ERBIUM DOPED FIBER IN SINGLE-PASS CONFIGURATION

SHAHIRAH SAADON

This Report Is Submitted In Partial Fulfillment Of Requirements For The

Bachelor Degree Of Electronic Engineering (Telecommunications Electronic)

Fakulti Kejuruteraan Elektronik Dan Kejuruteraan Komputer

Universiti Teknikal Malaysia Melaka

JUN 2013

1 2 / 1 3

UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek :

Sesi Pengajian :

WIDEBAND OPTICAL AMPLIFIER USING HIGH CONCENTRATION ERBIUM DOPED FIBRE IN SINGLE PASS CONFIGURATION

Saya SHAHIRAH BINTI SAADON

mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syarat- syarat kegunaan seperti berikut:

1. Laporan adalah hakmilik Universiti Teknikal Malaysia Melaka.

2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja.

3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara institusi

pengajian tinggi.

4. Sila tandakan ( √ ) :

SULIT* *(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)

TERHAD** **(Mengandungi maklumat terhad yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)

TIDAK TERHAD

Disahkan oleh:

(TANDATANGAN PENULIS) (COP DAN TANDATANGAN PENYELIA)

Tarikh: ……………………….. Tarikh: ………………………..

iii

“I hereby declare that this report is the result of my own work except for the

summary and quotes as cited in the reference”

Signature : …………………………………

Author : SHAHIRAH SAADON

Date : …………………………………

iv

“I hereby declare that I have read this report and in my opinion this report is

sufficient in terms of scope and quality for the award of the Bachelor of Electronics

Engineering (Telecommunications Engineering) With Honours”

Signature : …………………………………

Supervisor’s Name : ANAS BIN ABDUL LATIFF

Date : …………………………………

v

ACKNOWLEDGEMENT

Firstly, I would like to be grateful to Allah s.w.t. as I am able to fulfil the

Bachelor Project successfully. I would like to take this opportunity to express my

appreciation to those who has helped me through during the completion of this

project, especially to my supervisor; Mr. Anas bin Abdul Latiff for guiding me and

lending his knowledge towards accomplishing this project. In addition, I am

indebted to the Technical Staff of the Faculty of Electronics Engineering and

Computer Engineering for aiding me in conducting the experiment for the project in

the laboratory.

I would also like to than my parents for giving their never ending moral

supports and my fellow colleagues for their helping hand and encouragement in

finishing this project.

vi

ABSTRACT

This report explores the wideband optical amplifier using high concentration

erbium doped fibre in single-pass configuration. The main objective is to study the

design of Erbium doped Fibre Amplifier (EDFA) with low pump power to satisfy the

requirements for green technology specification. The design parameter for the

optimised circuit needs to be determined to evaluate the performance of the amplifier

so that it is able to transmit data efficiently. All the parameters and the fundamental

theory are described in details. The simulation result obtained will be analysed and

discussed.

vii

ABSTRAK

Laporan ini menerokai penguat optik jalur lebar yang menggunakan “Erbium

Doped Fiber” berkepekatan tinggi dalam konfigurasi pas-tunggal. Objektif utama

adalah untuk menganalisis bentuk “Erbium Doped Fiber Amplifier” (EDFA) dengan

kuasa pam yang rendah bagi memenuhi keperluan spesifikasi technology hijau.

Parameter reka bentuk litar optimum perlu ditentukan untuk menilai prestasi penguat

ini supaya ia dapat mengantar data dengan berkesan. Semua pamameter dan teori

asas akan diterangkan secara terperinci. Keputusan simulasi yang diperolehi akan

dianalisis dan dibincangkan.

viii

CONTENTS

CHAPTER

I

TITLE

PROJECT TITLE

VERIFICATION STATUS FORM

DECLARATION FORM

SUPERVISOR CONFIRMATION FORM

ACKNOWLEDGEMENT

ABSTRACT

CONTENT

LIST OF TABLE

LIST OF FIGURE

ABBREVIATION

LIST OF APPENDIX

INTRODUCTION

1.1 Overview of the Project

1.2 Objectives

1.3 Problem Statement

1.4 Scope

1.5 Project Outcomes

1.6 Methodology

1.7 Thesis Structure

PAGE

i

ii

iii

iv

v

vi

viii

xi

xii

xiv

xv

1

3

3

4

5

5

6

ix

II

III

LITERATURE REVIEW

2.1 Introduction 7

2.2 Benefits of Fibre Optics 8

2.3 Basic Fibre Optic Communication System 9

2.4 Optical Amplifier 10

2.4.1 Semiconductor Optical Amplifier 13

2.4.2 Raman Amplifier 14

2.4.3 Erbium Doped Fiber Amplifier 16

2.4.3.1 Amplifier Gain 17

2.4.3.2 Amplifier Noise 19

2.4.3.3 Crosstalk 23

2.4.3.4 Output Power 23

2.4.3.5 Power Saturation 26

2.4.4 Comparison between SOA, Raman and 27

EDFA

2.4.5 Advantage and Disadvantage of EDFA, 28

Raman, SOA

2.5 Parameters of Optical Amplifier (Performance) 29

2.5.1 Gain 30

2.5.2 Noise 30

2.5.3 Signal-to-Noise Ratio 31

2.5.4 Bit Error Rate 31

2.5.5 Eye Pattern 31

2.6 Wideband Fiber Amplifier 32

2.7 OptiSystem Software 35

METHODOLOGY

3.1 Project Flow Chart 36

3.2 Software Flow Chart 39

3.3 Project Block Diagram 41

3.4 Experimental Procedure 42

x

3.5 Parameters 43

IV RESULT AND DISCUSSION

4.1 Pump Laser Wavelength 45

4.1.1 980 nm Pump Laser 46

4.1.2 1480 nm Pump Laser 48

4.1.3 Optimized Pump Wavelength 50

4.2 Length of Fibre 54

4.3 Wideband Circuit 56

V CONCLUSION AND RECOMMENDATION

5.1 Conclusion 61

5.2 Recommendation 62

REFERENCES 64

APPENDIX 66

xi

LIST OF TABLES

TABLE

2.1

2.2

2.3

TITLE

Transmission Window

Characteristics of EDFA, Raman, and SOA

Advantages and Disadvantage of EDFA, Raman

and SOA

PAGE

12

27

28

xii

LIST OF FIGURES

FIGURE

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

2.11(a)

2.11(b)

2.11(c)

2.11(d)

3.1

3.2

TITLE

Fiber Transmission Cable

Optical Amplifier Transmission Windows

Semiconductor Optical Amplifier Construction

Spontaneous Raman Scattering

Stimulated Raman Scattering

EDFA Configuration

Set-up for Measurement of Amplifier Gain in

EDFA

Energy Level Diagram

Evolution of Pump, Signal and ASE

Gain as a Function of Input and Output Signal

Powers

Serial Configuration

Parallel Configuration

S-, C-, L-Bands Hybrid Configuration

Hybrid Combination of Raman Amplifier and

EDFA

Final Year Project Flow Chart

Software Flow Chart

PAGE

10

13

14

15

16

17

18

19

25

25

32

33

33

34

38

40

xiii

3.3

3.4(a)

3.4(b)

3.5(a)

3.5(b)

4.1(a)

4.1(b)

4.2(a)

4.2(b)

4.3(a)

4.3(b)

4.3(c)

4.4(a)

4.4(b)

4.5(a)

4.5(b)

4.6(a)

4.6(b)

4.6(c)

Evaluation Performance 41

Wideband Series Configuration 42

Wideband Parallel Configuration 42

Single Pump Configuration 44

Bidirectional (Backward-Forward) Pump 44

Configuration

Graph of C-band at 980 nm 46

Graph of L-band at 980 nm 47

Graph of C-band at 1480 nm 48

Graph of L-band at 1480 nm 49

C-band Optimum Pump Laser Wavelength 51

L-band Optimum Pump Laser Wavelength 52

Wideband Optimum Pump Laser Wavelength 53

Graph of C-band at different length 54

Graph of L-band at different length 55

Series configuration of EDFA 56

Parallel configuration of EDFA 57

Graph of Wideband Serial Configuration 58

Graph of Wideband Parallel Configuration 59

Analysis of wideband optimized configuration 60

xiv

ABBREVIATION

OA

EDFA

SOA

RA

NF

SNR

- Optical Amplifier

- Erbium Doped Fibre Amplifier

- Semiconductor Optical Amplifier

- Raman Amplifier

- Noise Figure

- Signal-to-Noise Ratio

xv

LIST OF APPENDIX

NO TITLE

A1 Table of C-band at Pump Wavelength of 980 nm

A2 Table of L-band at Pump Wavelength of 980 nm

B1 Table of C-band at Pump Wavelength of 1480 nm

B2 Table of L-Band at Pump Wavelength of 1480 nm

C1 Table of C-band at Different Length of Fibre

C2 Table of L-band at Different Length of Fibre

D1 Table of Wideband Serial Configuration

D2 Table of Wideband Parallel Configuration

PAGE

66

67

68

69

70

70

1

CHAPTER 1

INTRODUCTION

Chapter one focuses on the project’s overview, project’s objective and problem

statement, scope of work, methodology and thesis structure. It will explain the

basics for the project which is wideband optical amplifier using high Erbium Doped

Fibre Amplifier in single-pass configuration. These will be explained in this chapter

to give guidance to what the project is about.

1.1 Overview of the Project

In order to transmit signals over long distances (more than 100 km) it

is compulsory to calculate and compensate the attenuation losses within the

fibre, during travelling and also due to few other factors. Originally, this was

performed using the optoelectronic module that consisted of the optical

2

receiver, regeneration and equalisation system and also an optical transmitter

to transmit the data. Even though this arrangement was functional, it is

limited by the optical to electrical and electrical to optical conversions. Since

that, several types of optical amplifiers have been demonstrated to replace the

optical-electrical electronic regeneration system [1].

Erbium doped fibre amplifiers (EDFAs) is an optical repeater device

that is used to magnify the intensity of optical signals that are being carried

through a fibre optic telecommunication system. Commonly, an optical fibre

is doped with the rare earth element Erbium, which means that the Erbium is

added to the fibre core material as a dopant. This is so that the glass is able to

absorb light at one frequency and emits light at another frequency. Fibre

amplifiers are developed to support the Dense Wavelength Division

Multiplexing (DWDM) and to extend to the other wavelengths supported by

fibre optics. An external semiconductor laser couples light into the fibre at

infrared wavelengths of either 980 or 1480 nanometres. This operation will

excite the erbium atoms. Additional wavelengths between 1530 and 1620

nanometres infiltrate the fibre and stimulate the excited erbium atoms to emit

photons at the same wavelengths as the incoming signal. This operation

amplifies a flaccid signal to a greater power, affecting a magnification in the

signal strength.

This project simulated and evaluates the performance of the Erbium

Doped Fibre Amplifier in an optical transmission systems using the

OptiSystem Software. The performance of the amplifier is affected by few

parameters, which are; Optical Signal-to-Noise Ratio (OSNR), Bit Error Rate

(BER), and Noise Figure (NF). The problem faced on conducting this project

is to find the most excellent design parameter for the maximum utilization of

the Erbium Doped and with compact size using the Erbium Doped Fibre

Amplifier.

3

1.2 Objectives

The objectives of this project are:

a. To study the design of wideband optical amplifier using high

concentration erbium-doped Fibre using the OptiSystem software.

b. To provide the design parameters for low power and compact for

optical amplifier using high concentration Erbium Doped Fibre.

c. To evaluate the performance of the high concentration Erbium Doped

Fibre amplifier based on the amplifiers gain and Noise Figure (NF)

and to analyse the simulation data obtained from the OptiSystem

software.

1.3 Problem Statement

Optical amplifiers have become an essential component in the long

haul fibre optic systems due to the demand for the longer length of

transmission. During the transmission of the signal through the fibre cable,

there bound to be some losses due to few factors that cannot be avoided. The

reasons why the optical amplifiers are required are:

• Typical fibre loss for 1.5 µm is 0.2 dB/km.

• After travelling for about 100km, the signals will be attenuated

by 20 dB.

• The optical signal needs to be amplified so that the Optical

Signal-to-Noise Ratio (OSNR) of the detected signal is not too

low and the Bit Error Rate (BER) does not becomes too high.

• The previous amplifier which is the Optical-Electrical-Optical

amplifier conversions is much more expensive as it requires

expensive high-speed electronics.

4

• The most efficient and effective solution is to amplify the

signal optically by using the fibre amplifier because it is

lowest in cost, most efficient and most stable.

In order to increase the output power of the transmission system, the

amount of the optical amplifier will also need to be increased. However this

will also increase the costs. Therefore the best solution is by optimizing the

performance of the optical amplifier.

Currently, the most effectual solution in optimizing the performance

of the optical amplifier is by using the Erbium Doped Fibre Amplifier. This

is because their high gain and the ability to operate with low pump power.

Therefore, this project is to analyse the performance of the high concentration

Erbium Doped Fibre amplifier at different pumping value. The effectiveness

of the amplifier will be based on the value of the output that will be obtained.

The length of the fibre that is to be used in the amplifier will also need to be

reduced to reduce the cost needed for the construction of the amplifier. The

solution to this is by using the high concentration Erbium in the fibre to

enhance the energy excitement on the amplifier.

The design for the EDFA must fit the criteria of the objective, that it:

• It must be compact (try to minimize the length of fibre to be

used in the experiment.

• Try to use the lowest possible pump power to operate the

system, but with efficient result.

1.4 Scope

This project will focus primarily on the simulation of the wideband

optical amplifier using high concentration Erbium Doped Fibre in single pass

configuration. The simulation and tests will be done using the OptiSystem

Software. The performance of the optical amplifier will be evaluated based

5

on the amplifier’s gain and Noise Figure (NF) obtained from the simulation

of a single mode fibre transmission link for wideband wavelength. The

fabrication or development of hardware of the high concentration of Erbium

Doped Fibre Optical Amplifier (EDFA) will not be covered in this project.

1.5 Project Outcomes

It is expected that by the end of this project, the parametric study for

the design of the high concentration EDFA in single-pass configuration that is

to be used for the wideband with desired parameter of high gain value and

low noise figure value can be obtained. In addition, the EDFA will be able to

simulate with low power and is compact size.

1.6 Methodology

This project starts off with acquiring the source and information

pertaining to the optical amplifier using high concentration Erbium Doped

Fibre. The sources and information are obtained from journals, reference

books, e-Books, magazines and also the internet. The information attained

will be based on the fundamental configuration of the optical amplifier in a

transmission link, advantages and disadvantages of EDFA, the parameters

related with EDFA. The circuit schematic diagram of the optical amplifier

using high concentration Erbium Doped Fibre is determined and then

simulated and tested using the OptiSystem software. The parameters

involved and varied are the number of pump (Single Pump or Bidirectional

Pump), the pump power (from 10 mW until 200 mW), the pump wavelength

(980 nm or 1480 nm), the fibre length (from 1 m until 2.5 m for C-band

application and from 7 m until 8.5 m for L-band application) and the input

signal power (0 dBm or -30 dBm). The amplifiers gain and Noise Figure

(NF) obtained from the simulation is analysed. The simulation process is

6

repeated until the compatible design parameter for the wideband optical

amplifier is obtained.

1.7 Thesis Structure

Chapter 1 introduces the project and gives general idea regarding the

project. It includes the overview of the project, the objective, problem

statement, scope of project and project outcomes which will provide basic

idea and knowledge related with this project.

Chapter 2 illustrates and discusses the projects fundamental and

background. The concept and theory of the circuit diagram that will be used

in the project will be explained in details in this chapter.

Chapter 3 proposes the methodology of the project. The procedures

that will be used in conducting the project will be explained more thoroughly

in this chapter.

Chapter 4 presents the results that are obtained from the simulation of

the high concentration EDFA. The results obtained will also be discusses and

analysed in this chapter,

Chapter 5 will conclude all the information collected based on the

projects result. The results will be evaluated based on the findings and the

objectives of the project. Recommendations on how to enhance the project

will also be included in this chapter.

7

CHAPTER 2

LITERATURE REVIEW

Chapter two focuses on the project’s background and other relevant information

related to the project such as the fundamentals of Erbium Doped Fibre Amplifier. It

will explain the basics for the project which is wideband optical amplifier using high

Erbium Doped Fibre Amplifier in single-pass configuration.

2.1 Introduction

Since its invention in the early 1970s, the use and the demand of

optical fibre have excessively grown. The applications of optical fibre today

are quite abundant [1]. With the eruption of the information traffic generated

with the use of internet, electronic commerce, computer network, multimedia,

voice, data and video, the requirement for a transmission medium with the

8

bandwidth capabilities for handling such enormous amount of information is

essential. Fibre optics, with its comparatively infinite bandwidth has proven

to be the solution. When optical is the only transmission that can keep up

with and stay ahead of the accelerating demand for long haul requirements,

this means that the technology of the optical system is an essential part of the

human system [2]. Therefore, it is vital that we study the system in order to

develop the most intelligent fibre optic amplifier that fits the current needs to

allow for a more cost effective advance network infrastructure.

2.2 Benefits of Fibre Optics

The optical fibre system possesses several advantages over metallic-

based communication system [3]. These advantages include:

• Long distance signal transmission

The optical systems admits longer interval of signal transmission than

the metallic-based systems due to the low attenuation and superior

signal integrity.

• Large bandwidth, light weight, and small diameter

The present applications has the need to an ever increasing amount of

bandwidth. Therefore, it is important to acknowledge the space

constraints of many end users. The small diameter and light weight of

the optical cable makes the installation simple and practical, and helps

to save the conduit space.

• Non-conductivity

Due to its dielectric nature and no metallic components, the optical

fibres can be installed even in the areas with electromagnetic

interference (EMI) and radio frequency interference (RFI). It is also

ideal to be installed for the areas if high lightning strike incidence.

• Security

The dielectric nature of the optical fibre also makes it impossible to

remotely access the optical fibre. Accessing the fibre will require

9

intervention that will be easily discovered by the security surveillance.

The conditions make the fibre favoured to governmental bodies,

banks and others with security concerns.

• Designed for future application needs

Fibre optics is affordable today, as the prices of the electronics fall

and the price of the optical cable remaining low. In the increasing

demands of the bandwidth as the technology advances, fibre will

continue to play an essential role in the long term accomplishment of

the telecommunications.

2.3 Basic Fibre Optic Communication System

The fibre optics is used as medium to carry information from one

point to another in the form of light. As the fibre optic is not electrical in

nature like the copper form of transmission, a basic fibre optic system is

made up of a transmitting device that converts an electrical signal into a light

signal, an optical fibre that carries the light and a receiver that accepts the

light signal and convert is back to electrical signal. The complexity of a fibre

optic system can range from a very simple system to a very prominent

system. A conventional optical communication system that is for the usage

of long distance, high bandwidth telecommunication that employs

wavelength-division multiplexing uses the Erbium doped fibre amplifier, an

external modulation that uses the DFB lasers with temperature compensation,

fibre Bragg gratings and high speed infrared photo-detectors [4].