Fiber-Optic Communication Systems

by Govind P. Agrawal

Overview

Discover the latest developments in fiber-optic communications with the newest edition of this leading textbook

In the newly revised fifth edition of Fiber-Optic Communication Systems, accomplished researcher and author, Dr. Govind P. Agrawal, delivers brand-new updates and developments in the science of fiber optics communications. The book contains substantial additions covering the topics of coherence detection, space division multiplexing, and more advanced subjects. You'll learn about topics like fiber’s losses, dispersion, and nonlinearities, as well as coherent lightwave systems. The latter subject has undergone major changes due to the extensive development of digital coherent systems over the last decade. Space-division multiplexing is covered as well, including multimode and multicore fibers developed in just the last ten years. Finally, the book concludes with a chapter on brand-new developments in the field that are still at the development stage and likely to become highly relevant for practitioners and researchers in the coming years.

Readers will also benefit from the inclusion of:

• A thorough introduction to the fundamentals of fiber-optic communication systems
• An exploration of the management of fiber-optic communication losses, dispersion, and nonlinearities
• A practical discussion of coherent lightwave systems, including coherent transmitters and receivers, as well as noise and bit-error rate, sensitivity degradation mechanisms, and the impact of nonlinear effects
• A concise treatment of space-division multiplexing, including multicore and multimode fibers, multicore lightwave systems, and multimode lightwave systems
• Analyses of advanced topics, including pulse shaping for higher spectral efficiency, Kramers-Kronig receivers, nonlinear Fourier transform, wavelength conversion, and optical regeneration

Perfect for graduate students, professors, scientists, and professional engineers working or studying in the area of telecommunications technology, Fiber-Optic Communication Systems is an essential update to the leading reference in the area of fiber-optic communications.

Product Details

ISBN-13:	9781119737360
Publisher:	Wiley
Publication date:	06/29/2021
Series:	Wiley Series in Microwave and Optical Engineering Series
Edition description:	5th ed.
Pages:	544
Product dimensions:	7.10(w) x 10.10(h) x 1.50(d)

About the Author

Govind P. Agrawal, PhD, is James C. Wyant Professor at the Institute of Optics at the University of Rochester. He is a Fellow of the Optical Society of America and the IEEE. He is also a Senior Scientist at the Laboratory for Laser Energetics and has authored or co-authored over 400 research papers, book chapters, and monographs.

Read an Excerpt

Chapter 1: Introduction

A communication system transmits information from one place to another, whether separated by a few kilometers or by transoceanic distances. Information is often carried by an electromagnetic carrier wave whose frequency can vary from a few megahertz to several hundred terahertz. Optical communication systems use high carrier frequencies (- 100 THz) in the visible or near-infrared region of the electromagnetic spectrum. They are sometimes called lightwave systems to distinguish them from microwave systems, whose carrier frequency is typically smaller by five orders of magnitude (- 1 GHz). Fiber-optic communication systems are lightwave systems that employ optical fibers for information transmission. Such systems have been deployed worldwide since 1980 and have indeed revolutionized the technology behind telecommunications. Indeed, the lightwave technology, together with microelectronics, is believed to be a major factor in the advent of the "information age." The objective of this book is to describe fiber-optic communication systems in a comprehensive manner. The emphasis is on the fundamental aspects, but the engineering issues are also discussed. The purpose of this introductory chapter is to present the basic concepts and to provide the background material. Section 1.1 gives a historical perspective on the development of optical communication systems. In Section 1.2 we cover concepts such as analog and digital signals, channel multiplexing, and modulation formats. Relative merits of guided and unguided optical communication systems are discussed in Section 1.3. In Section 1.4 we describe the components of a fiber-optic communication system. The concept of channel capacity is introduced in Section 1.5.

1.1 Historical Perspective

The use of light for communication purposes dates back to antiquity if we interpret optical communications in a broad sense. Most civilizations have used fire and smoke signals to convey a single piece of information (such as victory in a war). Essentially the same idea was used up to the end of the eighteenth century through signaling lamps, flags, and other semaphore devices. The idea was extended further, following a suggestion of Claude Chappe in 1792, to transmit mechanically coded messages over long distances (- 100 km) by the use of intermediate relay stations (acting as regenerators or repeaters). The role of light was simply to make the coded signals visible so that they could be intercepted by relay stations. Such optical communication systems were inherently slow. Indeed, in modern-day terminology, the effective bit rate was less than 1 bit per second (B ‹1 b/s).

1.1.1 Need for Fiber-Optic Communications

The advent of telegraphy in the 1830s replaced the use of light by electricity and began the era of electrical communications. The bit rate B could be increased to - 10 b/s by the use of new coding techniques, such as Morse code. The use of intermediate relay stations allowed communication over long distances (- 1000 km). Indeed, the first successful transatlantic telegraph cable went into operation in 1866. Interestingly enough, telegraphy used essentially a digital scheme through two electrical pulses of different durations (dots and dashes of the Morse code). The invention of the telephone in 1876 brought a major change inasmuch as electric signals were transmitted in analog form through a continuously varying electric current. Analog electrical techniques were to dominate communication systems for a century or so.

The development of worldwide telephone networks during the twentieth century led to many advances in the design of electrical communication systems. The use of coaxial cables in place of wire pairs increased system capacity considerably. The first coaxial-cable system, put into service in 1940, was a 3-MHz system capable of transmitting 300 voice channels or a single television channel. The bandwidth of such systems is limited by the frequency-dependent cable losses, which increase rapidly for frequencies beyond 10 MHz. This limitation led to the development of microwave communication systems in which an electromagnetic carrier wave with frequencies of - 1 to 10 GHz is used to transmit the signal by using suitable modulation techniques. The first microwave system operating at the carrier frequency of 4 GHz was put into service in 1948. Since then, both coaxial and microwave systems have evolved considerably and are able to operate at bit rates of - 100 Mb/s. The most advanced coaxial system, put into service in 1975, operates at a bit rate of 274 Mb/s. A severe drawback of such a high-speed coaxial system is the small repeater spacing (- 1 km), which makes the system relatively expensive to operate. Microwave communication systems generally allow for a larger repeater spacing, but their bit rate is also limited by the carrier frequency of such waves. A commonly used figure of merit for communication systems is the bit rate-distance product, BL, where B is the bit rate and L is the repeater spacing. Figure 1.1 shows how the BL product has increased through technological advances during the last century and a half. Communication systems with BL - 100 (Mb/s)-km were available by 1970 and were limited to such values because of fundamental limitations.

It was realized during the second half of the twentieth century that an increase of several orders of magnitude in the BL product would be possible if optical waves were used as the carrier. However, neither a coherent optical source nor a suitable transmission medium was available during the 1950s. The invention of the laser and its demonstration in 1960 solved the first problem. Attention was then focused on finding ways for using laser light for optical communications. Many ideas were advanced during the 1960s, the most noteworthy being the idea of light confinement using a sequence of gas lenses. It was suggested in 1966 that optical fibers might be the best choice, as they are capable of guiding the light in a manner similar to the guiding of electrons in copper wires. The main problem was the high loss of optical fibers-fibers available during the 1960s had losses in excess of 1000 dB/km. A breakthrough occurred in 1970 when the fiber loss could be reduced to about 20 dB/km in the wavelength region near 1 µm. At about the same time, GaAs semiconductor lasers, operating continuously at room temperature, were demonstrated. The simultaneous availability of a compact optical source and a low-loss optical fiber led to a worldwide effort for developing fiber-optic communication systems. Figure 1.2 shows the progress in the performance of lightwave systems realized after 1974 through several generations of development. The progress has indeed been rapid, as is evident by a many-order-of-magnitude increase in the bit rate-distance product over a period of less than 25 years.

1.1.2 Five Generations of Lightwave Systems

The commercial deployment of lightwave systems followed the research and development closely. After many field trials, the first-generation lightwave systems operating near 0.8 µm became available commercially in 1980. They operated at a bit rate of 45 Mb/s and allowed a repeater spacing of about 10 km. The larger repeater spacing compared with that of a coaxial system was an important motivation for system designers, as it decreased the installation and maintenance costs associated with each repeater.

It was clear during the 1970s that the repeater spacing could be increased considerably by operating the lightwave system in the wavelength region near 1.3 µm where fiber loss is below 1 dB/km. Furthermore, optical fibers exhibit minimum dispersion in this wavelength region. This realization led to a worldwide effort for the development of InGaAsP semiconductor lasers and detectors operating near 1.3 µm The second generation of fiber-optic communication systems became available in the early 1980s, but the bit rate of early systems was limited to below 100 Mb/s because of dispersion in multimode fibers. This limitation was overcome by the use of single-mode fibers. A laboratory experiment in 1981 demonstrated 2-Gb/s transmission over 44 km of single-mode fiber. The introduction of commercial systems soon followed. By 1987, second-generation 1.3-µm lightwave systems, operating at bit rates of up to 1.7 Gb/s with a repeater spacing of about 50 km, were commercially available.

The repeater spacing of the second-generation lightwave systems was limited by the fiber loss at the operating wavelength of 1.3 µm (typically, 0.5 dB/km). The loss of silica fibers is minimum near 1.55 µm Indeed, a loss of 0.2 dB/km in this spectral region was realized in 1979. However, the introduction of third-generation lightwave systems operating at 1.55 µm was considerably delayed by large fiber dispersion near 1.55 µm Conventional InGaAsP semiconductor lasers could not be used because of pulse spreading occurring as a result of simultaneous oscillation of several longitudinal modes. The dispersion problem can be overcome either by using dispersion-shifted fibers designed to have minimum dispersion near 1.55 µm or by limiting the laser spectrum to a single longitudinal mode. Both approaches were followed during the 1980s. By 1985, laboratory experiments, indicated the possibility of transmitting information at bit rates of up to 4 Gb/s over distances in excess of 100 km. Third-generation 1.55-µm systems operating at 2.5 Gb/s became available commercially in 1990. Such systems are capable of operating at a bit rate of up to 10 Gb/s. The best performance is achieved using dispersion-shifted fibers together with single-longitudinal-mode lasers.

A drawback of third-generation 1.55-µm systems is that the signal is regenerated periodically by using electronic repeaters spaced apart typically by 60-70 km. The repeater spacing can be increased by making use of a homodyne or heterodyne detection scheme since its use improves receiver sensitivity. Such systems are referred to as coherent lightwave systems. Coherent systems were under development worldwide during the 1980s, and their potential benefits were demonstrated in many system experiments. However, commercial introduction of such systems had been delayed by the advent of fiber amplifiers in 1989.

The fourth generation of lightwave systems makes use of optical amplification for increasing the repeater spacing and of wavelength- division multiplexing (WDM) for increasing the bit rate. In such systems, fiber loss is compensated periodically by using erbium-doped fiber amplifiers spaced 60-100 km apart. Such amplifiers were developed during the 1980s and became available commercially by 1990. In 1991, an experiment showed the possibility of data transmission over 21,000 km at 2.5 Gb/s, and over 14,300 km at 5 Gb/s, by using a recirculating-loop configuration. This performance indicated that an amplifier-based, all-optical, submarine transmission system was feasible for intercontinental communication. By 1996, not only transmission over 11,300 km at a bit rate of 5 Gb/s had been demonstrated by using actual submarine cables, but a commercial transpacific cable (TPC-5) also became operational. Figure 1.3 shows the international network of undersea lightwave systems operational in 1996. Many other transoceanic lightwave systems have been planned. The 27,300-km fiber-optic link around the globe (known as FLAG) will begin operation in 1997, linking many Asian and European countries at 5 Gb/s, with several sections operating at 10 Gb/s. Another fiber-optic network, known as Africa One, will circle the African continent and cover a total transmission distance of about 35,000 km. Clearly, the fourth-generation systems have revolutionized the state of the art of lightwave systems.

The current emphasis of fourth-generation lightwave systems is on increasing the system capacity by transmitting multiple channels through the WDM technique. Optical amplifiers are ideal for multichannel lightwave systems since all channels can be amplified simultaneously without requiring demultiplexing of individual channels. In a 1996 demonstration, twenty 5-Gb/s channels were transmitted over 9100 km in a recirculating-loop configuration, resulting in a total bit rate of 100 Gb/s and the BL product of 910 (Tb/s)-km. In another record experiment, a total bit rate of 1.1 Tb/s was achieved by multiplexing 55 channels, each operating at 20 Gb/s. Despite the use of dispersion-compensation schemes, dispersive effects limited the total transmission distance to 150 km. Commercial WDM systems operating at a bit rate of up to 40 Gb/s were available by the end of 1996. A transpacific system (TPC-6) operating at 100 Gb/s is scheduled to begin operation by the year 2000. The bit rate-distance product for such a system exceeds 900 (Tb/s)-km, indicating the progress realized over a 20-year period.

The fifth generation of fiber-optic communication systems is concerned with finding a solution to the fiber-dispersion problem. Optical amplifiers solve the loss problem but, at the same time, make the dispersion problem worse since the dispersive effects accumulate over multiple amplification stages. Several dispersion-compensation techniques have been developed, as discussed in Chapter 9. An ultimate solution is based on the novel concept of optical solitons, optical pulses that preserve their shape during propagation in a lossless fiber by counteracting the effect of dispersion through the fiber nonlinearity. Although the basic idea was proposed as early as 1973, it was only in 1988 that a laboratory experiment demonstrated the feasibility of data transmission over 4000 km by compensating the fiber loss through stimulated Raman scattering. Erbium-doped fiber amplifiers were used for soliton amplification starting in 1989. Since then, many system experiments have demonstrated the eventual potential of soliton communication systems. By 1994, solitons were transmitted over 35,000 km at 10 Gb/s and over 24,000 km at 15 Gb/s. In a 1996 recirculating-loop experiment, soliton transmission over 9400 km was demonstrated at a bit rate of 70 Gb/s by multiplexing seven 10-Gb/s channels.

Even though the fiber-optic communication technology is barely two decades old, it has progressed rapidly and has reached a certain stage of maturity. This is also apparent from the publication of a large number of books on optical communications since 1991. This text, first published in 1992, is intended to present an up-to-date account of fiber-optic communications systems with an emphasis on recent developments....

Table of Contents

Preface xvi

1 Introduction 1

1.1 Historical Perspective 1

1.1.1 Need for Fiber-Optic Communications 2

1.1.2 Evolution of Lightwave Systems 4

1.2 Basic Concepts 8

1.2.1 Analog and Digital Signals 8

1.2.2 Channel Multiplexing 11

1.2.3 Modulation Formats 13

1.3 Optical Communication Systems 16

1.4 Lightwave System Components 18

1.4.1 Optical Fibers as a Communication Channel 18

1.4.2 Optical Transmitters 18

1.4.3 Optical Receivers 19

Problems 20

References 21

2 Optical Fibers 24

2.1 Geometrical-Optics Description 24

2.1.1 Step-Index Fibers 25

2.1.2 Graded-Index Fibers 27

2.2 Wave Propagation 29

2.2.1 Maxwell’s Equations 29

2.2.2 Fiber Modes 31

2.2.3 Single-Mode Fibers 34

2.3 Dispersion in Single-Mode Fibers 37

2.3.1 Group-Velocity Dispersion 38

2.3.2 Material Dispersion 39

2.3.3 Waveguide Dispersion 40

2.3.4 Higher-Order Dispersion 41

2.3.5 Polarization-Mode Dispersion 43

2.4 Dispersion-Induced Limitations 44

2.4.1 Basic Propagation Equation 45

2.4.2 Chirped Gaussian Pulses 46

2.4.3 Limitations on the Bit Rate 49

2.5 Fiber Losses 52

2.5.1 Attenuation Coefficient 52

2.5.2 Material Absorption 53

2.5.3 Rayleigh Scattering 54

2.5.4 Waveguide Imperfections 55

2.6 Nonlinear Optical Effects 56

2.6.1 Stimulated Light Scattering 56

2.6.2 Nonlinear Phase Modulation 60

2.6.3 Four-Wave Mixing 63

2.7 Fiber Design and Fabrication 64

2.7.1 Silica Fibers 64

2.7.2 Plastic Optical Fibers 67

2.7.3 Cables and Connectors 69

Problems 70

References 72

3 Optical Transmitters 75

3.1 Semiconductor Laser Physics 75

3.1.1 Spontaneous and Stimulated Emissions 76

3.1.2 Nonradiative Recombination 77

3.1.3 Optical Gain 78

3.1.4 Feedback and Laser Threshold 80

3.1.5 Laser Structures and Modes 81

3.2 Single-Mode Semiconductor Lasers 83

3.2.1 Distributed Feedback Lasers 83

3.2.2 Coupled-Cavity Semiconductor Lasers 85

3.2.3 Tunable Semiconductor Lasers 86

3.2.4 Vertical-Cavity Surface-Emitting Lasers 88

3.3 Semiconductor Laser Characteristics 89

3.3.1 CW Characteristics 89

3.3.2 Modulation Bandwidth 92

3.3.3 Relative Intensity Noise 94

3.3.4 Spectral Linewidth 97

3.4 Modulation Techniques 98

3.4.1 Direct Modulation 99

3.4.2 External Modulation 100

3.5 Light-Emitting Diodes 103

3.5.1 LED Characteristics 104

3.5.2 LED Structures 106

3.6 Transmitter Design 108

3.6.1 Source–Fiber Coupling 108

3.6.2 Driving Circuitry 110

3.6.3 Reliability and Packaging 111

Problems 113

References 115

4 Optical Receivers 119

4.1 Basic Concepts 119

4.1.1 Responsivity and Quantum Efficiency 119

4.1.2 Rise Time and Bandwidth 121

4.2 Common Photodetectors 122

4.2.1 p–n Photodiodes 122

4.2.2 p–i–n Photodiodes 124

4.2.3 Avalanche Photodiodes 127

4.2.4 MSM Photodetectors 133

4.3 Receiver Design 135

4.3.1 The Front End 135

4.3.2 The Linear Channel 137

4.3.3 Data-Recovery Section 138

4.3.4 Integrated Receivers 139

4.4 Receiver Noise 141

4.4.1 Noise Mechanisms 141

4.4.2 SNR of p–i–n Receivers 143

4.4.3 SNR of APD Receivers 144

4.5 Coherent Detection 148

4.5.1 Local Oscillator 148

4.5.2 Homodyne Detection 149

4.5.3 Heterodyne Detection 150

4.5.4 Signal-to-Noise Ratio 150

4.6 Receiver Sensitivity 151

4.6.1 Bit-Error Rate 151

4.6.2 Minimum Received Power 154

4.6.3 Quantum Limit of Photodetection 156

4.7 Sensitivity Degradation 157

4.7.1 Extinction Ratio 157

4.7.2 Intensity Noise 158

4.7.3 Timing Jitter 160

4.8 Receiver Performance 162

Problems 164

References 166

5 Lightwave Systems 170

5.1 System Architectures 170

5.1.1 Point-to-Point Links 170

5.1.2 Distribution Networks 172

5.1.3 Local-Area Networks 173

5.2 Design Guidelines 175

5.2.1 Loss-Limited Lightwave Systems 175

5.2.2 Dispersion-Limited Lightwave Systems 176

5.2.3 Power Budget 177

5.2.4 Rise-Time Budget 179

5.3 Long-Haul Systems 181

5.3.1 Performance-Limiting Factors 181

5.3.2 Terrestrial Lightwave Systems 183

5.3.3 Undersea Lightwave Systems 186

5.4 Sources of Power Penalty 188

5.4.1 Modal Noise 188

5.4.2 Mode-Partition Noise 190

5.4.3 Reflection Feedback and Noise 191

5.4.4 Dispersive Pulse Broadening 194

5.4.5 Frequency Chirping 195

5.4.6 Eye-Closure Penalty 197

5.5 Forward Error Correction 198

5.5.1 Error-Correcting Codes 198

5.5.2 Coding Gain 199

5.6 Computer-Aided Design 200

Problems 202

References 204

6 Multichannel Systems 208

6.1 WDM Systems and Networks 208

6.1.1 High-Capacity Point-to-Point Links 209

6.1.2 Wide-Area and Metro-Area Networks 212

6.1.3 Multiple-Access WDM Networks 215

6.2 WDM Components 216

6.2.1 Optical Filters 217

6.2.2 Multiplexers and Demultiplexers 222

6.2.3 Add–Drop Multiplexers 224

6.2.4 Star Couplers 227

6.2.5 Wavelength Routers 228

6.2.6 WDM Transmitters and Receivers 230

6.3 System Performance Issues 233

6.3.1 Linear Crosstalk 233

6.3.2 Raman-Induced Nonlinear Crosstalk 235

6.3.3 XPM-Induced Nonlinear Crosstalk 237

6.3.4 FWM-Induced Nonlinear Crosstalk 239

6.3.5 Other Design Issues 240

6.4 Time-Division Multiplexing 241

6.4.1 Time-Domain Multiplexing 242

6.4.2 Time-Domain Demultiplexing 243

6.4.3 Performance of OTDM Systems 245

6.5 Subcarrier Multiplexing 246

6.5.1 Analog and Digital SCM Systems 246

6.5.2 Orthogonal Frequency-Division multiplexing 248

6.6 Code-Division Multiplexing 250

6.6.1 Time-Domain Encoding 251

6.6.2 Frequency-Domain Encoding 253

Problems 255

References 257

7 Loss Management 264

7.1 Compensation of Fiber Losses 264

7.1.1 Periodic Amplification Scheme 265

7.1.2 Lumped Versus Distributed Amplification 267

7.1.3 Bidirectional Pumping Scheme 268

7.2 Erbium-Doped Fiber Amplifiers 269

7.2.1 Pumping and Gain Spectrum 269

7.2.2 Two-Level Model 270

7.2.3 Amplifier Noise 273

7.2.4 Multichannel Amplification 275

7.3 Raman Amplifiers 277

7.3.1 Raman Gain and Bandwidth 278

7.3.2 Raman-Induced Signal Gain 279

7.3.3 Multiple-Pump Raman Amplification 281

7.3.4 Noise Figure of Raman Amplifiers 283

7.4 Optical Signal-To-Noise Ratio 285

7.4.1 Lumped Amplification 285

7.4.2 Distributed Amplification 287

7.5 Electrical Signal-To-Noise Ratio 288

7.5.1 ASE-Induced Current Fluctuations 288

7.5.2 Impact of ASE on SNR 290

7.5.3 Noise Buildup in an Amplifier Chain 291

7.6 Receiver Sensitivity and Q Factor 292

7.6.1 Bit-Error Rate 292

7.6.2 Relation between Q Factor and Optical SNR 294

7.7 Role of Dispersive and Nonlinear Effects 295

7.7.1 Noise Growth through Modulation Instability 295

7.7.2 Noise-Induced Signal Degradation 297

7.7.3 Noise-Induced Energy Fluctuations 299

7.7.4 Noise-Induced Timing Jitter 300

7.8 Periodically Amplified Lightwave Systems 300

7.8.1 Numerical Approach 301

7.8.2 Optimum Launched Power 304

Problems 306

References 307

8 Dispersion Management 310

8.1 Dispersion Problem and Its Solution 310

8.2 Dispersion-Compensating Fibers 312

8.2.1 Conditions for Dispersion Compensation 312

8.2.2 Dispersion Maps 313

8.2.3 DCF Designs 315

8.3 Fiber Bragg Gratings 317

8.3.1 Constant-Period Gratings 318

8.3.2 Chirped Fiber Gratings 320

8.3.3 Sampled Gratings 322

8.4 Dispersion-Equalizing Filters 325

8.4.1 Gires–Tournois Filters 325

8.4.2 Mach–Zehnder and Other Filters 327

8.5 Optical Phase Conjugation 329

8.5.1 Principle of Operation 330

8.5.2 Compensation of Self-Phase Modulation 331

8.5.3 Generation of Phase-Conjugated Signal 332

8.6 Advanced Techniques 335

8.6.1 Tunable Dispersion Compensation 335

8.6.2 Higher-Order Dispersion Management 338

8.6.3 PMD Compensation 340

8.7 Electronic Dispersion Compensation 343

8.7.1 Pre-compensation at the Transmitter 343

8.7.2 Post-Compensation at the Receiver 347

Problems 349

References 351

9 Control of Nonlinear Effects 355

9.1 Impact of Fiber Nonlinearity 355

9.1.1 System Design Issues 356

9.1.2 Semianalytic Approach 359

9.1.3 Soliton and Pseudo-linear Regimes 361

9.2 Solitons in Optical Fibers 363

9.2.1 Properties of Optical Solitons 364

9.2.2 Loss-Managed Solitons 367

9.2.3 Dispersion-Managed Solitons 370

9.2.4 Timing Jitter 374

9.3 Pseudo-linear Lightwave Systems 378

9.3.1 Origin of Intrachannel Nonlinear Effects 378

9.3.2 Intrachannel Cross-Phase Modulation 380

9.3.3 Intrachannel Four-Wave Mixing 384

9.4 Management of Nonlinear Effects 387

9.4.1 Optimization of Dispersion Maps 387

9.4.2 Phase-Alternation Technique 390

9.4.3 Polarization Bit Interleaving 392

9.4.4 Optical Phase Conjugation 393

9.4.5 Phase-Sensitive Amplification 395

Problems 396

References 398

10 Coherent Lightwave Systems 402

10.1 Coherent Transmitters 403

10.1.1 Encoding of Optical Signals 403

10.1.2 Amplitude and Phase Modulators 405

10.1.3 Quadrature modulator 406

10.2 Coherent Receivers 408

10.2.1 Synchronous Heterodyne Demodulation 408

10.2.2 Asynchronous Heterodyne Demodulation 410

10.2.3 Optical Delay Demodulation 411

10.2.4 Phase Diversity and Polarization Diversity 413

10.3 Noise and Bit-Error Rate 415

10.3.1 Synchronous Heterodyne Receivers 415

10.3.2 Asynchronous Heterodyne Receivers 418

10.3.3 Receivers with Optical Delay Demodulation 419

10.4 Sources of Performance Degradation 421

10.4.1 Intensity Noise of Lasers 421

10.4.2 Phase Noise of Lasers 422

10.4.3 Effects of Fiber’s Dispersion 424

10.5 Management of Nonlinear Effects 425

10.5.1 Nonlinear Phase Noise 426

10.5.2 Compensation of Nonlinear Phase Noise 429

10.5.3 Nonlinear Interference Noise 432

10.6 Digital Signal Processing 435

10.6.1 Removal of Intermediate Frequency and Phase fluctuations 435

10.6.2 Compensation of GVD and PMD 437

10.6.3 Digital Backward Propagation 440

10.7 Experimental Progress 442

10.7.1 DPSK and DQPSK formats 442

10.7.2 QPSK and QAM formats 445

10.7.3 Coherent Orthogonal FDM 448

10.7.4 Optical Superchannels 450

10.8 Channel Capacity 452

Problems 454

References 455

11 Space-Division Multiplexing 462

11.1 SDM Technique 462

11.2 Modes of Optical Fibers 464

11.2.1 Step-Index Fibers 464

11.2.2 Graded-Index Fibers 467

11.2.3 Multicore Fibers 469

11.3 SDM Components 471

11.3.1 Design of SDM Fibers 471

11.3.2 Spatial Multiplexers and Demultiplexers 474

11.3.3 Multicore/Multimode Fiber Amplifiers 479

11.3.4 Other SDM Components 481

11.4 Modeling of SDM Systems 482

11.4.1 Multimode Coupled Nonlinear Equations 483

11.4.2 Averaged Multimode Nonlinear Equations 486

11.4.3 Nonlinear Effects in MCFs 488

11.4.4 Nonlinear Effects in MMFs 491

11.5 Experimental Progress 494

11.5.1 MCF-Based SDM Systems 494

11.5.2 MMF-Based SDM Systems 496

11.5.3 High-Capacity SDM Systems 498

Problems 499

References 500

12 Advanced Topics 505

12.1 Optical Signal Processing 506

12.1.1 Nonlinear Optical Loop Mirrors 506

12.1.2 Parametric Amplifiers 510

12.1.3 Semiconductor Optical Amplifiers 513

12.1.4 Bistable Optical Devices 516

12.1.5 Optical Flip–Flops 518

12.2 Wavelength Conversion 522

12.2.1 XPM-Based Wavelength Converters 522

12.2.2 FWM-Based Wavelength Converters 525

12.2.3 Semiconductor Waveguides 528

12.2.4 SOA-Based Wavelength Converters 530

12.3 Ultrafast Optical Switching 532

12.3.1 Time-Domain Demultiplexing 532

12.3.2 Packet Switching 536

12.3.3 Format Conversion 538

12.4 Optical Regeneration 540

12.4.1 2R Regenerators 541

12.4.2 3R Regenerators 545

12.4.3 Regeneration of Phase-Encoded Signals 549

12.5 Nonlinear Frequency-Division Multiplexing 552

12.5.1 Nonlinear Fourier Transform 552

12.5.2 Practical Implementation 554

Problems 556

References 557

A System of Units 566

B Acronyms 568

C Formula for Pulse Broadening 572

D Nyquist Pulses 574

References 575

Index 576

What People are Saying About This

From the Publisher

"Despite the otherwise excellent quality of the book, there are also several typos, in the text as well as in the problems." (Optics and Photonics News, 13 May 2011)

Editorial Reviews

...an excellent introduction...this is undoubtedly one of the best, most comprehensive and technologically advanced textbooks available...""...I feel this a must for a researcher in the field of fiber-optic communications.

Glass Technology

The first edition of this book is well known all over the world and had a great echo anywhere.... Because of...rapid advances it was necessary to bring out the second edition in order to continue to provide a comprehensive and up-to-date account of fiber-optic communication systems.

Optik: International Journal for Light and Electron Optics

The first edition of this book is well known all over the world and had a great echo anywhere.... Because of...rapid advances it was necessary to bring out the second edition in order to continue to provide a comprehensive and up-to-date account of fiber-optic communication systems.

Optik

Physical understanding and engineering aspects of fiber optic communication systems are emphasized in this book/CD-ROM text covering both the systems and components of fiber optic communication systems and the physics and technology behind them. This third edition has been updated to reflect the current state of the art in lightwave transmission systems, with particular emphasis on the rapid development of WDM technology and on system design issues pertaining to current topics of research. The companion CD-ROM contains system design software. Although intended as a text for graduate students of fiber optics communications, the book can also be a resource for senior undergraduate courses and a reference for researchers and engineers in telecommunications and lightwave technology. Agrawal teaches at the Institute of Optics at the University of Rochester. Annotation c. Book News, Inc., Portland, OR (booknews.com)

A textbook for a graduate or senior undergraduate engineering course on optical communications, containing enough material that a selection of topics is required to fit into one semester. Emphasizes the physical understanding of fiber-optic technology, but also discusses engineering aspects. Updated and considerably expanded from the 1992 edition. Annotation c. by Book News, Inc., Portland, Or.

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