Performance Evaluation Of Filtering For Wavelength Division Multiplexing Based Optical Fiber Networks

Abstract 

The transmission distance of any WDM fiber-optic communication system is eventually limited by fiber losses and it was introduced from fiber attenuation, connectors, splices, dispersion, interference and bending causes the power reduction in optical fiber communication. This loss limitation was mostly overcome using tunable optical filters, devices in which the desired channel is to be selected at the receiver with negligible crosstalk and small insertion loss. In this thesis different kinds of tunable optical filters such as: Fabry-Perot, Machzehnder and Acuosto-Optic filters are implemented to compensate losses. From the obtained results, it will be shown that a WDM optical system with a Machzehnder filter gets the best performance to compensate losses than Fabry-Perot and acuosto-optic filters in terms of Q-factor, BER, eye height and threshold when a fiber length, attenuation coefficient and input power design parameters are changed. Also fabry-perot filter produced better results at all cases than acuosto-optic filter which has a bad performance than others.

Table of Contents

Acknowledgments ii

Abstract iii

iv المستخلص

List of Figures viii

List of Tables xiv

List of Abbreviations xv

List of Symbols xvi

Chapter One: Introduction 1

1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Proposed Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.4 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.5 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.6 Thesis organization . . . . . . . . . . . . . . . . . . . . . . . . . 2

Chapter Two: Background and Literature Review 3

2.1 Multiplexing techniques . . . . . . . . . . . . . . . . . . . . . . 3

2.1.1 WDM technique . . . . . . . . . . . . . . . . . . . . . . 3

2.1.2 OTDM technique . . . . . . . . . . . . . . . . . . . . . . 4

2.1.3 SCM technique . . . . . . . . . . . . . . . . . . . . . . . 4

2.1.4 CDM technique . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Tunable Optical Filters . . . . . . . . . . . . . . . . . . . . . . . 5

2.2.1 Fabry–Perot Filter . . . . . . . . . . . . . . . . . . . . . 7

2.2.2 Mach–Zehnder Filter . . . . . . . . . . . . . . . . . . . . 7

2.2.3 Grating-based optical Filter . . . . . . . . . . . . . . . . 8

2.2.4 Michelson optical Filter . . . . . . . . . . . . . . . . . . 8

2.2.5 Acousto-optic Filter . . . . . . . . . . . . . . . . . . . . 8

2.3 Literature Review . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Chapter Three: System Model and Design Approach 11

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2.1 System model with Fabry–Perot Filter . . . . . . . . . 12

3.2.2 System model with Mach-Zehnder Filter . . . . . . . . 12

3.2.3 System model with Acousto-Optic Filter . . . . . . . . 13

3.3 Limiting factors for performance of the WDM networks . . . . 13

3.4 Performance evaluation of the WDM networks . . . . . . . . . 13

3.4.1 Quality factor . . . . . . . . . . . . . . . . . . . . . . . . 14

3.4.2 Bit-error rate . . . . . . . . . . . . . . . . . . . . . . . . 14

3.4.3 Eye height . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.4.4 Threshold Considerations . . . . . . . . . . . . . . . . . 15

3.4.5 Eye Diagram . . . . . . . . . . . . . . . . . . . . . . . . 15

Chapter Four: Results and Discussion 17

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.2 Performance Analysis For Filtering WDM Based Optical Fiber Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.2.1 Performance Analysis With a Fabry–Perot Tunable Filter 17

4.2.1.1 Effect Of Fiber Length . . . . . . . . . . . . . 18

4.2.1.2 Effect Of Attenuation Coefficient . . . . . . . 26

4.2.1.3 Effect Of Input Power . . . . . . . . . . . . . 33

4.2.2 Performance Analysis With a Mach-Zehnder Tunable Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.2.2.1 Effect Of Fiber Length . . . . . . . . . . . . . 39

4.2.2.2 Effect of Attenuation Coefficient . . . . . . . 47

4.2.2.3 Effect Of Input Power . . . . . . . . . . . . . 54

4.2.3 Performance Analysis With An Acousto-Optic Tunable Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4.2.3.1 Effect Of Fiber Length . . . . . . . . . . . . . 61

4.2.3.2 Effect Of Attenuation Coefficient . . . . . . . 68

4.2.3.3 Effect Of Input Power . . . . . . . . . . . . . 74

4.2.4 Comparison Of Performance Evaluation Of Filtering For WDM Based Optical Fiber Networks . . . . . . . . 80

4.2.4.1 Different Fiber Length . . . . . . . . . . . . . 80

4.2.4.2 Different Fiber Attenuation . . . . . . . . . . 84

4.2.4.3 Different Input Power . . . . . . . . . . . . . . 88

4.3 The pass band characteristics of tunable optical filters . . . . . 92

Chapter Five: Conclusions and Recommendations 95

5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

5.2 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Bibliography 97