DWDM

Preface xvii

Acknowledgments xix

List of Physical Constants xxi

Introduction xxiii

1 The Physics of Optical Components 1

1.1. Introduction 1

1.2. The Nature of Light 3

1.2.1. The Wave Nature of Light 3

1.2.2. The Particle Nature of Light 7

1.2.3. Huygens-Fresnel Principle 8

1.2.4. Interference 8

1.2.5. Holography 10

1.2.6. Optical Correlators and Storage 12

1.2.7. Light Attributes 12

1.3. Optical Materials 13

1.3.1. Transparent Versus Opaque Matter 13

1.3.2. Homogeneity and Heterogeneity 13

1.3.3. Isotropy and Anisotropy 13

1.3.4. Organic Materials 14

1.3.5. Photochromaticity 14

1.4. Light Meets Matter 15

1.4.1. Reflection and Refraction: Snell's Law 15

1.4.2. Critical Angle 16

1.4.3. Antireflection 17

1.4.4. Prisms and Superprisms 18

1.4.5. Propagation of Light 20

1.4.6. Diffraction 22

1.4.7. Polarization 25

1.4.8. Extinction Ratio 33

1.4.9. Phase Shift 34

1.4.10. Birefringence 34

1.4.11. Material Dispersion 37

1.4.12. Electro-Optic Effects 38

1.4.13. Material Attributes 41

1.5. The Fiber as an Optical Transmission Medium 41

1.5.1. Composite Refractive Indices 44

1.5.2. Fiber Modes 44

1.5.3. Fiber Attenuation and Power Loss 49

1.5.4. Fiber Birefringence 54

1.5.5. Dispersion 55

1.5.6. Spectral Broadening 72

1.5.7. Self-Phase Modulation 73

1.5.8. Self-Modulation or Modulation Instability 73

1.5.9. Effect of Pulse Broadening on Bit Error Rate 74

1.6. Nonlinear Phenomena 75

1.6.1. Stimulated Raman Scattering 76

1.6.2. Stimulated Brillouin Scattering 77

1.6.3. Four-Wave Mixing 77

1.6.4. Temporal FWM, Near-End and Far-End 79

1.6.5. Impact of FWM on DWDM Transmission Systems 80

1.6.6. Countermeasures to Reduce FWM 80

1.7. Solitons 80

1.8. Summary of Nonlinear Phenomena 82

1.9. Factors that Affect Matter and Light 82

1.10. Regarding Optical Fiber 83

1.10.1. Ideal Fiber Versus Real Fiber 84

1.10.2. The Evolving Bandwidth-Span Product 84

1.10.3. Fiber Amplifiers and Spectral Continuum 84

1.10.4. New Fibers 85

1.10.5. How Strong Is Fiber? 86

1.11. Fiber Connectivity 86

1.12. Optical PWBs 87

Exercises 88

References 89

Standards 91

2 Optical Components 93

2.1. Introduction 93

2.1.1. Geometrical Optics 93

2.1.2. Insertion Loss and Isolation 95

2.1.3. Parameters Common to All Components 95

2.2. Optical Filters 96

2.2.1. Fabry-Perot Interferometer 98

2.2.2. Dielectric Thin Film 104

2.2.3. Diffraction Gratings 105

2.2.4. Bragg Gratings 110

2.2.5. Mach-Zehnder Interferometry 116

2.2.6. Arrayed Waveguide Grating Filters 118

2.2.7. Polarizing Filters 120

2.2.8. Absorption Filters 121

2.2.9. Acousto-Optic Tunable Filters 122

2.2.10. Hybrid Filters 124

2.2.11. Comparing Tunable Filters 124

2.3. Optical Directional Couplers 125

2.4. Optical Power Attenuators 128

2.5. Polarizers and Rotators 129

2.6. Beam Splitters 129

2.7. Optical Isolators and Circulators 130

2.8. Quarter-Wavelength and Half-Wavelength Plates 132

2.9. Optical Multiplexers and Demultiplexers 132

2.9.1. Prisms and Superprisms 132

2.9.2. Gratings 133

2.9.3. Mach-Zehnder Demultiplexer 133

2.9.4. Arrayed Waveguide Grating Demultiplexers 133

2.9.5. Channel Interleavers and Channel Splitters 134

2.10. Optical Cross-Connects 135

2.10.1. Free-Space Optical Switching 137

2.10.2. Solid-State Cross-Connects 140

2.10.3. Polymers and Inks 142

2.10.4. Photochromic Materials 143

2.10.5. Technologies and Switching Speeds 143

2.11. Optical Add-Drop Multiplexers 145

2.12. Optical Equalizers 147

2.13. Light Sources 149

2.13.1. Light-Emitting Diodes 150

2.13.2. Lasers 152

2.14. Laser Beams 166

2.14.1. Gaussian Beams 166

2.14.2. Near-Field and Far-Field Distribution 167

2.14.3. Peak Wavelength 168

2.14.4. Degree of Coherence 168

2.14.5. Laser Safety 169

2.15. Modulators 171

2.15.1. Types of Modulators 173

2.15.2. A Case: Amplitude Modulation 174

2.15.3. Modulation and Bit Error Probabilities 175

2.16. Photodetectors and Receivers 178

2.16.1. The PIN Photodiode 181

2.16.2. The APD Photodiode 181

2.16.3. Photodetector Figure of Merit 183

2.16.4. ITU-T Nominal Center Frequencies 183

2.17. Optical Amplifiers 183

2.17.1. Semiconductor Optical Amplifiers 186

2.17.2. Rare Earth-Doped Fiber Optical Amplifiers 187

2.17.3. Optical Parametric Amplifiers 197

2.17.4. Raman Amplifiers 198

2.17.5. Synergistic Amplification 205

2.17.6. Stimulated Brillouin Scattering 205

2.17.7. Amplification in the Low-Loss Spectral Range 206

2.18. Wavelength Converters 208

2.18.1. Cross-Gain Modulation 208

2.18.2. Cross-Phase Modulation 209

2.18.3. Four-Wave Mixing 209

2.18.4. Optical Frequency Shifting 209

2.19. Optical Phase-Locked Loops 210

2.20. Ring Resonators 211

2.21. Optical Attenuators 212

2.22. Optical Signal-to-Noise Ratio 212

2.22.1. Bit Error Rate 213

2.22.2. BER and Eye Diagram 215

2.23. New Materials and Components 219

2.23.1. Optical Materials 219

2.23.2. Hollow Fibers 220

2.23.3. Lasers and Receivers 220

2.23.4. Optical Cross-Connects 221

2.23.5. Optical Memories 221

2.23.6. Optical Integration 222

Exercises 222

References 224

Standards 233

3 Communications Fundamentals 235

3.1. Introduction 235

3.2. Pulse Coded Modulation 236

3.3. Loop Accessing Methods 237

3.3.1. xDSL 238

3.3.2. Other High-Speed Short-Reach Technologies 242

3.4. Time Division Multiplexing Systems 244

3.4.1. Access and Pair-Gain Systems 246

3.4.2. Fiber-to-the-Home Technology 249

3.4.3. Switching Systems 251

3.4.4. Digital Cross-Connect Systems 253

3.5. Getting Connected 254

3.6. Data Systems 255

3.6.1. The OSI Model 258

3.6.2. Local Area Networks 260

3.6.3. Packet Networks 265

3.6.4. Frame Relay 267

3.6.5. ATM 267

3.6.6. Quality of Service 269

3.7. SONET and SDH 270

3.7.1. SONET Topologies 271

3.7.2. SONET and SDH Rates 271

3.7.3. SONET and SDH Frames 271

3.7.4. Floating Frames and Pointers 275

3.7.5. Overhead Definition 275

3.7.6. Frequency Justification 278

3.7.7. Path Overhead 278

3.7.8. Maintenance 278

3.7.9. Operations Communications Interface 280

3.7.10. Interworking 281

3.7.11. Next-Generation SONET 282

3.8. Internet 282

3.8.1. Voice over IP 283

3.8.2. Fax over IP (FoIP) 284

3.8.3. ATM over SONET 285

3.8.4. IP over SONET 287

3.9. Optical Networks 287

3.10. What Is a DWDM System and Network? 288

Exercises 289

References 290

Standards 292

4 DWDM Systems 294

4.1. Introduction 294

4.2. DWDM Network Topologies-Review 295

4.3. DWDM Systems and Network Layers 299

4.3.1. DWDM and Standards 299

4.3.2. Domains or Functions 301

4.3.3. System Partitioning and Remoting 301

4.4. Key Building Blocks of a DWDM System 303

4.4.1. Transmitters and Receivers 304

4.4.2. Optical Amplifiers and Regenerators 311

4.4.3. Dispersion Compensating Solutions 318

4.4.4. Optical Gain Equalizers 322

4.4.5. Optical Wavelength Translators 324

4.4.6. Timing 325

4.4.7. Optical Switching 327

4.4.8. Control Architectures and Controllers 329

4.4.9. Interfaces 332

4.5. Wavelength Management Strategy 339

4.6. Equipment Sensing Strategy 345

4.7. Fault Detection and Reporting Strategy 346

4.7.1. Fault Detection on the Network Level 347

4.7.2. Fault Detection Identifiers 348

4.7.3. Overhead, Data, and Error Correction: The Digital Wrapper 348

4.8. Power Strategy 353

4.9. DWDM Systems by Network Layer 354

4.9.1. Point-to-Point Systems 354

4.9.2. Large Optical Cross-Connect Systems 358

4.9.3. DWDM Metro Systems 361

4.9.4. Access DWDM Systems and First Last Mile 366

4.10. Protected and Unprotected Systems 368

4.11. Engineering DWDM Systems 370

4.11.1. Parameters That Influence Optical Design 370

4.11.2. ITU-T Recommended Frequencies 372

4.11.3. Channel Capacity, Width, and Spacing 372

4.11.4. Channel Bit Rate and Modulation 372

4.11.5. Multichannel Frequency Stabilization 373

4.11.6. BER and Channel Performance 373

4.11.7. Channel Dispersion 373

4.11.8. Power Launched 373

4.11.9. Optical Amplification and Compensation 374

4.11.10. The Fiber-Medium and Limitations 374

4.11.11. Optical Power Budget 374

4.11.12. Power Budget Calculations by

Example 375

Conclusions 379

Exercises 381

References 382

Standards 384

5 DWDM Networks 388

5.1. Introduction 388

5.1.1. Multiprotocol Label Switching 390

5.1.2. MP?S 391

5.1.3. DiffServ, IntServ, and MPLS 392

5.1.4. Optical Virtual Path Network 392

5.1.5. Network Layers and Protection 392

5.1.6. The Evolving Telecommunications Management Network 393

5.2. The Optical Transport Network 394

5.3. DWDM Network Topologies and Restoration Strategies 397

5.3.1. Point-to-Point Topology 401

5.3.2. Ring Topology 403

5.3.3. Mesh Topology 406

5.3.4. Ring-Mesh Networks 410

5.4. Dispersion Management 410

5.5. Bandwidth Management 411

5.5.1. Wavelength Management 412

5.5.2. Traffic Management 413

5.5.3. Congestion Management 414

5.6. Fiber Span Between Transmitter and Receiver 415

5.7. Fault Management 416

5.8. Network Security 417

5.9. DWDM Network Issues 417

5.9.1. Interoperability and Internetworking 418

5.9.2. Optical Performance Monitoring 418

5.9.3. Network Future-Proofing 419

5.9.4. Wavelength Sharing 419

5.9.5. IPSONET over DWDM 419

5.9.6. Maintenance 419

5.9.7. DWDM Network Management 421

5.10. Wireless DWDM Networks 421

Exercises 422

References 423

Standards 425

6 Emerging Technologies 428

6.1. Introduction 428

6.2. Emerging Technologies 428

6.2.1. Theory and New Materials 429

6.2.2. Communications Components, Systems, and Networks 430

6.2.3. Intelligent Homes 432

6.2.4. Intelligent Transportation 433

6.2.5. Intelligent Powering Systems 434

6.3. Current Research 434

6.3.1. Advanced Lasers 434

6.3.2. Artificial Optical Materials 435

6.3.3. Optical Cross-Connect 435

6.3.4. Optical Memories and Variable Delay Lines 436

6.3.5. Nonintrusive Optical Sensors 436

6.4. Conclusion 436

References 436

Standards 437

Answers to Exercises 439

Acronyms 445

Index 463

About the Author 487