Troubleshooting Optical Fiber Networks (eBook)

Front Cover 1
Troubleshooting Optical-Fiber Networks 4
Copyright Page 5
Contents 8
Foreword 14
Chapter 1. Early developments 18
1.0 Introduction 18
1.1 The birth of the OTDR 19
1.2 Features, functions, and performance improvements 21
1.3 Summary 26
Suggested reading 28
Chapter 2. Fundamentals of fiber optics 30
2.0 Introduction 30
2.1 Total internal reflection 30
2.2 Fiber attenuation 36
2.3 Numerical aperture 40
2.4 Multipath (modal) dispersion 41
2.5 Chromatic dispersion 45
2.6 Wavelength-division-multiplexed systems 52
2.7 V-parameter, cut-off wavelength, and spot profile 53
2.8 Splices and connectors 59
2.9 Bending loss 65
2.10 Coherence 69
2.11 Summary 72
Suggested reading 74
Problems 74
Chapter 3. Fundamentals of OTDR operation 76
3.0 Introduction 76
3.1 OTDR design 79
3.2 A typical OTDR waveform 80
3.3 Multiple-wavelength OTDRs 82
3.4 Optical masking 84
3.5 Evolution of the OTDR 86
3.6 Rayleigh backscatter 89
3.7 Dynamic range 91
3.8 Differences between multimode and single-mode OTDRs 95
3.9 Echoes and ghosts 104
3.10 Other types of OTDR configurations 108
3.11 Summary 116
Suggested reading 117
Problems 118
Chapter 4. Performance characteristics of OTDRs 120
4.0 Introduction 120
4.1 Figures of merit 120
4.2 Historical figures of merit 122
4.3 Detailed figures of merit 124
4.4 Standards 166
4.5 Summary 167
Suggested reading 168
Problems 168
Chapter 5. Measuring nonreflective events 170
5.0 Introduction 170
5.1 Sources of nonreflective events 170
5.2 Cursor placement for manual loss and distance measurements 173
5.3 Distance-measurement errors of nonreflective events 175
5.4 Summary 193
Suggested reading 194
Problems 195
Chapter 6. Loss-measurement error 196
6.0 Introduction 196
6.1 Loss-measurement errors caused by waveform noise 196
6.2 Loss-measurement errors due to mismatch of single-mode fibers 202
6.3 Loss-measurement errors on multimode fiber 207
6.4 Bending loss and stress loss in single-mode fibers 213
6.5 Wavelength-dependent loss in fusion splices and connectors between single-mode fibers 215
6.6 Intrinsic loss in single-mode fusion splices 217
6.7 Summary 222
Suggested reading 223
Problems 223
Chapter 7. Measuring reflective events 226
7.0 Introduction 226
7.1 Background 226
7.2 Causes of reflection 229
7.3 Measuring reflective events using an OTDR 238
7.4 Effects that can reduce the accuracy of reflectivity measurements 243
7.5 Calibrating the OTDR’s backscatter coefficient 246
7.6 Integrated return loss 257
7.7 Summary 262
Suggested reading 264
Problems 264
Chapter 8. Complications caused by reflective events 266
8.0 Introduction 266
8.1 Reflections and the dead zone 266
8.2 Improving the dead zone by optical masking 269
8.3 Impact of reflections on transmitters and receivers 274
8.4 Dead zone box 280
8.5 Summary 282
Suggested reading 282
Problems 282
Chapter 9. Measuring the numerical aperture and mode-field diameter of single-mode fiber 284
9.0 Introduction 284
9.1 The far-field scanning method of determining numerical aperture 285
9.2 Measuring the numerical aperture of single-mode fiber using an OTDR 289
9.3 Measuring the cut-off wavelength of a single-mode fiber using an OTDR 292
9.4 Summary 294
Suggested reading 294
Problems 295
Chapter 10. Analyzing passive networks containing splitters and couplers 296
10.0 Introduction 296
10.1 Determining the locations of breaks in systems containing splitters 301
10.2 OTDR requirements for testing networks with splitters 304
Suggested reading 306
Problems 307
Chapter 11. Automatic event-marking algorithms and calibration 308
11.0 Introduction 308
11.1 Types of event markings 308
11.2 Functionality of different types of event markings 310
11.3 Optimizing acquisition parameters 315
11.4 Measuring individual events 321
11.5 Testing event-marking software 329
11.6 Event-marking features 334
11.7 Remote OTDRs for monitoring networks 338
11.8 Summary 342
Suggested reading 343
Problems 344
Chapter 12. Test fixtures 346
12.0 Introduction 346
12.1 Dead zone fixture 346
12.2 Fiber circulator 347
12.3 External-source test fixture 354
12.4 Loss calibration with fiber standard 355
12.5 Summary 357
Suggested reading 358
Problems 359
Chapter 13. Polarization mode dispersion 360
13.0 Introduction 360
13.1 Measurement techniques 363
13.2 PMD model of optical fiber 366
13.3 Mathematical model of a polarization OTDR 370
13.4 Summary 374
Problems 375
Chapter 14. Dispersion in optical fibers 376
14.0 Introduction 376
14.1 Intermodal dispersion 378
14.2 Intramodal dispersion 381
14.3 Dispersion reduction in optical fibers 385
14.4 Measuring dispersion using an OTDR 386
14.5 Measuring chromatic dispersion using multiple-wavelength OTDRs 389
14.6 Summary 392
Suggested reading 393
Problems 394
Chapter 15. Considerations when selecting an OTDR 396
15.0 Introduction 396
15.1 Durability 397
15.2 Display and controls 399
15.3 Human interface 403
15.4 Optical port 404
15.5 Accessories, options, and features 411
15.6 Safety 413
15.7 Performing a fiber-acceptance test 416
15.8 Measuring the splice attenuation 419
15.9 When should OTDR traces be taken? 421
15.10 Span measurements 422
15.11 Field technician’s top-ten list 423
15.12 Summary 424
Problems 424
Glossary of Terms 426
Mathematical Glossary 442
Answers to Problems 448
Index 450