Practical Fiber Optics (eBook)

Cover 1
Contents 5
Preface 
12 
1. Introduction 15
1.1 Historical background to fiber optics 16
1.2 Comparison of fiber optic and copper cabling systems 18
1.2.1 Bandwidth 18
1.2.2 Interference 19
1.2.3 Electrical Isolation 19
1.2.4 Transmission distances 19
1.2.5 Size and weight 20
1.2.6 Use in hazardous gas areas 20
1.2.7 Security 20
1.2.8 Multi-dropping for LANs 21
1.2.9 Jointing and connectors 21
1.2.10 Terminal equipment 21
1.2.11 Test equipment and testing 21
2. Definitions and fundamental principles 22
Data communications 22
2.1 Transmitters, receivers and communication channels 22
2.1.1 Interface standards 23
2.1.2 Coding 23
2.1.3 Protocols 24
2.2 Types of communication channels 25
2.2.1 Analog communications channels 25
2.2.2 Digital communications channels 26
2.3 Communications channel properties 26
2.3.1 Signal measurement on a communications channel 26
2.3.2 Signal attenuation 28
2.3.3 Channel bandwidth 30
2.3.4 Noise 31
2.4 Data transmission modes 32
2.4.1 Direction of signal flow 32
2.4.2 Synchronization of digital data signals 33
2.4.3 Asynchronous transmission 33
2.4.4 Synchronous transmission 35
2.5 Light 36
2.5.1 Electromagnetic waves 36
2.5.2 Photons 36
2.6 The electromagnetic spectrum 37
2.6.1 Optical region of the spectrum 38
2.7 Revisiting copper cables 38
2.7.1 Cable types 38
2.7.2 Cable structure 38
2.8 Factors affecting copper cable performance 40
2.8.1 Attenuation 40
2.8.2 Crosstalk 40
2.8.3 Characteristic impedance 40
2.9 Coaxial cable 41
2.9.1 Coaxial cable components 41
2.9.2 Coaxial cable connectors 42
2.9.3 Baseband versus broadband over coaxial cable 42
2.9.4 Advantages of a coaxial cable 43
2.9.5 Disadvantages of coaxial cable 43
2.10 Twisted pair cables 43
2.10.1 Components of twisted pair cable 44
2.10.2 Shielded twisted pair (STP) cable 45
2.10.3 Unshielded twisted pair (UTP) cable 45
2.10.4 Cable categories 45
2.10.5 Performance requirements 46
2.10.6 Advantages of twisted pair cable 49
2.10.7 Disadvantages of twisted pair cable 49
2.11 Sources of interference and noise on cables 49
2.11.1 Electrostatic coupling 50
2.11.2 Magnetic coupling 51
2.11.3 Impedance coupling 53
3. Theory of fiber optic transmission 56
3.1 Fundamental principles of operation 56
3.1.1 Introduction 56
3.1.2 Reflection, refraction and diffraction 57
3.1.3 Refractive index 58
3.1.4 Snell's law 60
3.1.5 Internal reflection 61
3.1.6 External reflection 62
3.1.7 Construction of an optical fiber 62
3.1.8 Fresnal reflection 63
3.2 The light transmission nature of glass 64
3.3 Numerical aperture 65
3.4 Modal propagation in fibers 68
3.4.1 Introduction 68
3.4.2 Modal disperson 69
3.4.3 Number of modes 71
3.4.4 Leaky modes 72
3.4.5 Refractive index profile 72
3.4.6 Multimode step and graded index fibers 73
3.4.7 Singlemode fibers 78
3.4.8 A comparison of data rate, distance and fiber type 80
3.4.9 Cost 80
3.5 Bandwidth 81
3.6 Wave division multiplexing 82
3.7 Effects on optical signal transmission 82
3.7.1 Chromatic dispersion 83
3.7.2 Absorption losses 85
3.7.3 Scatter losses 86
3.7.4 Bending losses 86
3.7.5 Radiation losses 87
3.7.6 Fresnal connection loss 88
3.7.7 Fiber size and NA mismatch 88
3.8 Other losses 89
3.9 Other types of fibers 89
3.9.1 Plastic fibers 89
3.9.2 Ultraviolet fibers 90
3.9.3 Mid infrared fibers 90
3.9.4 Polarised fibers 90
3.10 Fabrication of fibers 91
3.10.1 Inside chemical vapor deposition 91
3.10.2 Outside chemical vapor deposition 92
3.10.3 Vapor axial deposition 92
3.10.4 Double crucible drawing 93
4. Fibre optic cable construction 95
4.1 Basic cable construction objectives 95
4.1.1 Mechanical protection 95
4.1.2 Easier handling 95
4.1.3 Environmental protection 96
4.1.4 All-dielectric cables (galvanic isolation) 96
4.2 Fiber tensile ratings 96
4.3 Cable structural elements 97
4.4 Central member 98
4.5 Strength members 98
4.5.1 Metallic strength members 98
4.5.2 Non-metallic strength members 98
4.6 Fiber housing 98
4.6.1 Loose buffer construction 99
4.6.2 Loose tube construction 99
4.6.3 Slotted core construction 100
4.6.4 Tight buffered fibers 100
4.6.5 Ribbon cable construction 101
4.7 Moisture barrier 102
4.8 Cable sheaths 102
4.9 Cable armouring 103
4.10 Classes of fiber optic cables 103
4.10.1 Aerial cable 103
4.10.2 Underground cable 105
4.10.3 Subaqueous cables 106
4.10.4 Indoor cables 107
5. Connecting fibers 111
Introduction 111
5.1 Optical connection issues 111
5.1.1 Lateral misalignment of fiber cores 112
5.1.2 Differences in core diameters 113
5.1.3 Angular fiber misalignment 113
5.1.4 Numerical aperture differences 115
5.1.5 Reflection at the end of fibers 116
5.1.6 End separation of fibers 116
5.1.7 End finish and cleanliness of fibers 118
5.1.8 Connection loss summary 118
5.2 Fiber end preparation 118
5.2.1 Preparation of glass fibers 118
5.2.2 Scribe and break method 118
5.2.3 Cleavering tool 118
5.2.4 Lap and polish method 119
5.2.5 Preparation for plastic fibers 119
5.3 Splicing fibers 119
5.3.1 Fusion splicing 119
5.3.2 Fusion splicing process 121
5.3.3 Mechanical splicing 121
5.4 Connectors 125
5.4.1 Connector properties 125
5.4 2 General connector construction 126
5.4.3 Common connector types 128
5.4.4 Connector handling 130
5.4.5 Pig-tail 130
5.5 Optical couplers 131
6. Optical drivers and detectors 134
Introduction 134
6.1 Optical sources 134
6.2 Light emitting diodes (LED) 134
6.2.1 Construction 134
6.2.2 Basic LED operating principles 135
6.2.3 LED geometry 137
6.2.4 Operating characteristics 137
6.2.5 Practical LED devices 138
6.3 Laser diodes 139
6.3.1 Basic principles of a laser operation 139
6.3.2 Operating characteristics 140
6.3.3 Practical laser devices 141
6.3.4 Advances in laser technology 142
6.4 Optical transmitter modules 142
6.5 Laser safety considerations 143
6.6 Optical detectors 143
6.7 Pin photodiodes 143
6.7.1 Operating principles 143
6.7.2 Operating characteristics 144
6.7.3 PIN photodiode packaging 146
6.8 Avalanche photodiodes 146
6.8.1 Operating principles 146
6.8.2 Avalanche photodiode structure 146
6.8.3 Operating characteristics 147
6.8.4 Avalanche photodiode applications 148
6.9 Optical receiver modules 148
6.9.1 Basic elements of a ractical receive 148
6.9.2 Amplifiers 148
6.9.3 Receiver packaging 150
6.10 Optical amplifiers 150
6.10.1 Doped fibers 150
6.10.2 Semiconductor laser amplifiers 151
7. Installing fiber optic cables 152
7.1 Initial preparation for a cable installation 152
7.1.1 Site survey 152
7.1.2 Designing the cabling system 153
Introduction 152
7.2 General installation rules and procedures 156
7.2.1 Cable bend radius 156
7.2.2 Cable tension 158
7.2.3 Cable reels 160
7.2.4 Installation in cable trays 161
7.2.5 Installation in conduits 163
7.2.6 Leaving extra cable 166
7.2.7 Lubricants 167
7.2.8 Environmental conditions 168
7.3 Indoor cable installations 168
7.4 Outdoor cable installations 170
7.5 Other installation methods 172
7.5.1 Aerial installations 172
7.5.2 Blown fibers 173
7.6 Splicing trays/organizers and termination cabinets 174
7.6.1 Splicing trays 174
7.6.2 Splicing enclosures 175
7.6.3 Termination in patch panels and distribution frames 178
8. Fiber optic system design 180
Introduction 180
8.1 Initial design considerations 181
8.1.1 Data transmisson technology 181
8.1.2 Transmission parameters 181
8.1.3 Future data transmission capacity growth 181
8.1.4 Reliability 182
8.1.5 Selecting an operating wavelength 183
8.1.6 Cable selection and installation route 184
8.1.7 Repeaters and amplifiers 185
8.1.8 Transmitter and receiver equipment selection 185
8.2 Design loss calculations 186
8.2.1 Definition of parameters 186
8.2.2 Methodology for loss budget calculations 189
8.2.3 Example calculation 191
8.3 Design bandwidth calculations 192
8.3.1 Time response 192
8.3.2 Overall system time response 194
8.3.3 Optical fiber time response 194
8.3.4 Transmitter and receiver time response 196
8.3.5 Example of bandwidth calculation 196
9. Testing of fiber optic systems 198
Introduction 198
9.1 Fundamental concepts of optical measurement 198
9.1.1 Optical power 198
9.1.2 Power measurement 200
9.1.3 Optical and electrical bandwidth 201
9.2 Standard fiber optic tests 201
9.2.1 Component testing 201
9.2.2 Continuity testing 202
9.2.3 Insertion loss testing 203
9.2.4 Optical time domain reflectometers 204
9.2.5 The cold clamp 207
9.2.6 Bit error rate testing 207
9.2.7 Time domain measurements (eye diagrams) 209
9.3 Other fiber optic tests 211
9.3.1 Wavelength measurement 211
9.3.2 Dispersion measurement 212
9.3.3 Bandwidth measurement 212
9.3.4 Phase measurement 213
9.3.5 Polarization measurement 214
9.3.6 Miscellaneous measurements 214
10. Technologies that use optical fibers 215
Introduction 215
10.1 Communications systems 216
10.1.1 Analog systems 216
10.1.2 TV modulators 216
10.1.3 Cable TV 216
10.1.4 Digital systems 217
10.1.5 Undersea cables 217
10.1.6 HDTV 217
10.2 Local area network applications 218
10.2.1 FOIRL 218
10.2.2 10BaseF 218
10.3 MAN and WAN applications 222
10.3.1 SONET and SDH 222
10.3.2 B-ISDN 224
10.3.3 Asynchronous transfer mode (ATM) 224
10.3.4 Frame relay 225
10.3.5 Fiber channel 226
10.4 Sensors 228
10.4.1 Environmental sensors 230
10.4.2 Fiber optic gyroscopes 230
10.5 Bundled fiber applications 231
Appendix A: Glossary 
232 
Index 260