Optical Switching
Description
Comprehensive coverage of optical switching technologies and their applications in optical networks
Optical Switching: Device Technology and Applications in Networks delivers an accessible exploration of the evolution of optical networks with clear explanations of the current state-of-the-art in the field and modern challenges in the development of Internet-of-Things devices. A variety of optical switches--including MEMS-based, magneto, photonic, and SOA-based--are discussed, as is the application of optical switches in networks.
The book is written in a tutorial style, easily understood by both undergraduate and graduate students. It describes the fundamentals and recent developments in optical switch networks and examines the architectural and design challenges faced by those who design and construct emerging optical switch networks, as well as how to overcome those challenges. The book offers ways to assess and analyze systems and applications, comparing a variety of approaches available to the reader. It also provides:
* A thorough introduction to switch characterization, including optical, electro optical, thermo optical, magneto optical, and acoustic-optic switches
* Comprehensive explorations of MEMS-based, SOA-based, liquid crystal, photonic crystal, and optical electrical optical (OEO) switches
* Practical discussions of quantum optical switches, as well as nonlinear optical switches
* In-depth examinations of the application of optical switches in networks, including switch fabric control and optical switching for high-performance computing
Perfect for researchers and professionals in the fields of telecommunications, Internet of Things, and optoelectronics, Optical Switching: Device Technology and Applications in Networks will also earn a place in the libraries of advanced undergraduate and graduate students studying optical networks, optical communications, and sensor applications.
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Persons
Dalia Nandi is Assistant Professor of Electronics and Telecommunication Engineering at the Indian Institute of Information Technology, India.
Sandip Nandi is Assistant Professor of Electronics and Communication Engineering at the Kalyani Government Engineering College, India.
Angsuman Sarkar is Professor of Electronics and Communication Engineering at the Kalyani Government Engineering College, India.
Chandan Kumar Sarkar is Professor of Electronics and Telecommunication Engineering at Jadavpur University in India.
Content
Preface xvi
About the Editors xviii
List of Contributors xix
Part A Introduction 1
Introduction 3
Sandip Nandi and Dalia Nandi
A. Optical Communication Networks 3
A.1 Historical Perspective 3
A.2 Essential Background 6
A.2.1 Optical Networks 6
A.2.2 SONET/SDH 6
A.2.3 Multiplexing 7
A.2.4 All-Optical Networks 7
A.2.5 Optical Transport Network 8
B. Optical Switching in Networks 8
B.1 Historical Perspective 8
B.2 Essential Background 9
B.2.1 Optical Switching in Networks 9
B.2.2 Optical Switching in Practice 9
B.2.3 Optical Switch Technology 10
C. Organization of This Book 10
Bibliography 11
Part B Switch Characterization 13
1 Optical Switches 15
Rajan Agrahari, Sambit Kumar Ghosh, and Somak Bhattacharyya
1.1 Introduction 15
1.2 Electro-Optical Switching 16
1.2.1 Working Principle of Electro-Optical Switches 16
1.2.2 Realization of Electro-Optical Switches 17
1.3 Acoustic-Optical Switching 18
1.3.1 Types of Acoustic-Optical Switching 18
1.3.2 Acoustic-Optical Device Materials and Applications 19
1.4 Thermo-Optical Switching 19
1.4.1 Working Principle of Thermo-Optical Switches 20
1.4.2 Realization of Thermo-Optical Switches 20
1.4.3 Thermo-Optical Switch Materials and Applications 21
1.5 Liquid Crystal-Optical Switching 21
1.5.1 Types of Liquid Crystal-Optical Switches 21
1.5.2 Liquid Crystal-Optical Switch Applications 22
1.6 Photonic Crystal Optical Switching 22
1.7 Semiconductor Optical Amplifier (SOA) Optical Switching 23
1.8 Magneto-Optical (MO) Optical Switching 25
1.9 Micro Electro-Mechanical Systems (MEMS) Optical Switching 25
1.10 Metasurfaces Switches 26
1.11 Conclusion 26
Bibliography 27
2 Electro-Optic Switches 31
Arpita Adhikari, Joydip Sengupta, and Arijit De
2.1 Introduction 31
2.2 Operating Principles 32
2.2.1 Operating Principles of the Single-Mode Switch 32
2.2.2 Operating Principles of the Multimode Switch 32
2.3 Materials for the Fabrication of Electro-Optic Switch 34
2.3.1 Ferroelectric Materials 34
2.3.2 Compound Semiconductors 35
2.3.3 Polymers 35
2.4 Device Structures of Electro-Optical Switches 36
2.4.1 1 × 1 Switch 36
2.4.2 1 × 2 Switch 37
2.4.3 2 × 2 Switch 39
2.4.4 2 × 3 Switch 40
2.4.5 3 × 2 Switch 41
2.4.6 3 × 3 Switch 42
2.4.7 1 × 4 Switch 42
2.4.8 2 × 4 Switch 43
2.5 Conclusions 43
Bibliography 44
3 Thermo-Optical Switches 47
Fulong Yan, Xuwei Xue, and Chongjin Xie
3.1 History of Thermal Optical Switching 47
3.2 Principles of Thermo-Optic Switch 47
3.2.1 Thermo-Optic Effect 47
3.2.2 Trade-Off Between Switching Time and Power Consumption 48
3.2.3 Merits of Thermo-Optic Switch 49
3.3 Category 49
3.3.1 Material 49
3.3.2 Implementation Principle 51
3.3.3 Device Architecture 51
3.4 Scalability 52
3.4.1 Binary Tree 52
3.4.2 Modified Crossbar 53
3.4.3 Benes 54
3.5 Application Scenarios 54
Bibliography 55
4 Magneto-Optical Switches 57
K. Sujatha
4.1 Introduction 57
4.1.1 Types of Optical Switch 57
4.1.2 How Does an Optical Switch Work? 59
4.1.3 Applications of Optical Switches 59
4.2 All-Optical Switch 60
4.2.1 Why is an All-Optical Switch Useful? 62
4.3 Magneto-Optical Switches 64
4.3.1 Magneto-Optical Switch Features 64
4.3.2 Principles of Magneto-Optical Switches 65
4.3.2.1 The Design Core of the Magneto-Optical Switch 65
4.3.3 Magneto-Optic Effect 66
4.4 Faraday Rotation 68
4.4.1 Phenomenological Model 68
4.4.2 Atomic Model 68
Bibliography 70
Further Reading 70
5 Acousto-Optic Switches 73
Sudipta Ghosh, Chandan Kumar Sarkar, and Manash Chanda
5.1 Introduction 73
5.2 Fundamentals of Acousto-Optic Effect 73
5.3 Acousto-Optic Diffraction 74
5.4 Raman-Nath Diffraction 76
5.5 Bragg Diffraction 77
5.6 Principle of Operation of AO Switches 78
5.7 Acousto-Optic Modulator 80
5.7.1 Acousto-Optic Q-Switching 81
5.7.2 Telecommunication Network 82
5.8 Recent Trends and Applications 83
5.8.1 Emerging Spatial Mode Conversion in Few-Mode Fibers 83
5.8.2 Lithium Niobate Thin Films 84
5.8.3 Optical Fiber Communication and Networking 85
Bibliography 86
6 MEMS-based Optical Switches 93
Kalyan Biswas and Angsuman Sarkar
6.1 Introduction 93
6.2 Micromachining Techniques 94
6.2.1 Bulk Micromachining 95
6.2.2 Surface Micromachining 95
6.3 Switch Architectures 97
6.3.1 One-Dimensional Switches 97
6.3.2 Two-Dimensional MEMS Switches 97
6.3.3 Three-Dimensional MEMS Switches 98
6.4 Mechanisms of Actuations 100
6.4.1 Electrostatic Actuation 100
6.4.2 Magnetic Actuation 100
6.4.3 Thermal Actuation 100
6.4.4 Piezoelectric Actuation Mechanisms 100
6.4.5 Other Actuation Mechanisms 101
6.5 Optical Switch Parameters 101
6.5.1 Switching Time 102
6.5.2 Insertion Loss 102
6.5.3 Crosstalk 102
6.5.4 Wavelength 102
6.5.5 Power Consumption 102
6.6 Challenges 103
6.6.1 Optical Beam Divergence 103
6.6.2 Angular Control 103
6.6.3 Reliability of Optical MEMS 103
6.7 Conclusion 104
Bibliography 104
7 SOA-based Optical Switches 107
Xuwei Xue, Shanguo Huang, Bingli Guo, and Nicola Calabretta
7.1 Introduction 107
7.2 SOA Structure 107
7.2.1 Active Region 108
7.2.2 Inter-Band Versus Intra-Band Transition 109
7.2.3 Transparency Threshold 110
7.2.4 Gain Nonlinearity 111
7.2.5 Polarization-Insensitive SOA 111
7.2.6 Noise in SOA 112
7.3 Design Criteria of SOA-Based Switch 113
7.3.1 Effect of Doping on Gain Dynamics 113
7.3.2 Gain Dynamic for SOA 115
7.3.2.1 Bulk-Active Regions 116
7.3.2.2 Quantum Well/Multi-Quantum Well (MQW) Active Regions 116
7.3.2.3 Quantum Dots 116
7.3.3 Noise Suppression 117
7.3.4 Scalability 118
7.4 Advancements on SOA-Based Switch 120
7.5 Networks Employing SOA-Based Switch 122
7.5.1 Metro-Access Network 122
7.5.2 RF Network 122
7.5.3 Silicon Photonic Switching 122
7.5.4 Data Center Network 123
7.6 Discussion and Future Work 123
Bibliography 124
8 Liquid Crystal Switches 129
Swarnil Roy and Manash Chanda
8.1 Introduction 129
8.2 Liquid Crystal and Its Properties 131
8.3 LC Structures for Optical Switching 131
8.3.1 Twisted Nematic (TN) cells 131
8.3.2 Surface-Stabilized Ferroelectric Liquid Crystal (SSFLC) Cells 133
8.3.3 Spatial Light Modulator (SLM) Cells 133
8.4 Liquid Crystal Switches 134
8.4.1 Optical Crystal Switching Architectures 134
8.4.2 Switches Based on Polarization 135
8.4.2.1 Performance Analysis of Polarization-Based Switch Architecture 136
8.4.3 LC Amplitude and Phase Modulator 138
8.4.4 LC-Based Wavelength-Selective Switches (WSS) 140
8.4.4.1 WSS Based on LCOS 141
8.5 The Future of LC switches 141
8.5.1 Liquid Crystal Photonic Crystal Fibers 141
8.5.2 Ring Resonators with LC 142
Bibliography 142
9 Photonic Crystal All-Optical Switches 147
Rashmi Kumari, Anjali Yadav, and Basudev Lahiri
9.1 Idea of Photonics 147
9.2 Principles of Photonic Crystal All-Optical Switches (AOS) 148
9.3 Growth and Characterization of Optical Quantum Dots 150
9.3.1 Integration of PhCs-Based AOS with Optical Quantum Dots (QDs) 150
9.3.2 Growth and Characterization of Quantum Dots 152
9.3.2.1 Growth of Quantum Dots 152
9.3.2.2 Colloidal Solution Via Chemical Synthesis 152
9.3.2.3 Self-Assembly Technique 153
9.3.2.4 Characterization of Quantum Dots 154
9.3.2.5 Photoluminescence Spectroscopy 154
9.3.2.6 UV-Vis Spectroscopy 154
9.4 Design and Fabrication 155
9.4.1 Sample Preparation 155
9.4.2 Lithography 155
9.4.2.1 Electron Beam Lithography (EBL) 155
9.4.2.2 Optical UV Lithography 155
9.4.3 Etching 155
9.4.3.1 Wet Etching 155
9.4.3.2 Dry Etching 156
9.5 Device Structure and Performance Analysis of Photonic Crystal All-Optical Switches 156
9.6 Challenges and Recent Research Trends of Photonic Crystal All-Optical Switches 159
Bibliography 160
10 Optical-Electrical-Optical (O-E-O) Switches 165
Piyali Mukherjee
10.1 Introduction 165
10.2 Optical Switching Technologies: Working Principle 166
10.2.1 Optical-Electrical-Optical Switching 166
10.2.2 Optical Data Unit Switching 167
10.2.3 Reconfigurable Optical Add-Drop Multiplexer (ROADM)-Based Switching 168
10.2.4 A hybrid approach 169
10.3 Optical Transponders 169
10.3.1 WDM Transponders: An Introduction 169
10.3.2 Basic Working of Optical Transponders 170
10.3.3 Necessity of Optical Transponder (OEO) in WDM System 171
10.3.4 Applications of Optical Transponders 171
10.3.5 Network Structure with Optical Transponder 172
10.3.5.1 WDM Ring Employing Line Network 172
10.3.5.2 WDM Ring Employing Star Network 172
10.3.6 Differences Between Transponder, Muxponder, and Transceiver 173
10.3.7 Summary 174
10.4 Performance Analysis Study of All-Optical Switches, Electrical Switches, and Hybrid Switches in Networks 174
10.4.1 Introduction 174
10.4.2 Optical vs. Electrical vs. Hybrid Telecom Switches 175
10.4.3 Optical vs. Electrical vs. Hybrid Data Center Switches 177
10.4.4 Summary 179
10.5 Electrical and Optoelectronic Technology for Promoting Connectivity in Future Systems 179
10.5.1 CMOS Technology 180
10.5.2 Considerations for Selection of Interconnects 180
10.6 Conclusion 181
Bibliography 181
11 Quantum Optical Switches 185
Surabhi Yadav and Aranya B. Bhattacherjee
11.1 Introduction 185
11.2 Quantum Dot as an Optical Switch 186
11.2.1 Vertical Cavities 187
11.2.2 Power Density 189
11.3 Quantum Well as an Optical Switch 191
11.3.1 Optical Properties 191
11.3.2 Self-Electro-Optic-Effect Devices 193
11.4 Optomechanical Systems as Optical Switch 193
11.4.1 Optical Nonlinearity 193
11.4.2 Hybrid Optomechanics 195
11.4.3 Electro-opto Mechanics 198
11.5 Conclusion and Future Outlook 198
Bibliography 199
12 Nonlinear All-Optical Switch 203
Rajarshi Dhar, Arpan Deyasi, and Angsuman Sarkar
12.1 Introduction 203
12.2 Classification of All-Optical Switches 203
12.2.1 Thermo-Optical Switch 203
12.2.2 Acousto-Optic Switch 204
12.2.3 Liquid Crystal Optical Switch 206
12.2.4 Nonlinear Optical Switch 207
12.3 Classification of Nonlinear All-Optical Switches 207
12.3.1 Optical Coupler AOS 208
12.3.2 Sagnac Interferometer AOS 210
12.3.3 M-Z Interferometer AOS 210
12.3.4 Ring Resonator AOS 211
12.3.5 Fiber Grating AOS 212
12.4 Working Methodology of Different Types of Nonlinear All-Optical Switches 212
12.4.1 Optical Coupler AOS 212
12.4.1.1 Symmetric Coupler Working at Low Incident Power 213
12.4.1.2 Symmetric Coupler Working in High-Power Incident Light with SPM 214
12.4.1.3 Asymmetric Coupler Working in High-Power Pump Light with Cross-phase Modulation 217
12.4.2 Sagnac Interferometer AOS 219
12.4.2.1 Sagnac Interferometer (SI) Under Low Incident Power 219
12.4.2.2 Sagnac Interferometer AOS with Non-3dB Coupler 220
12.4.2.3 Sagnac Interferometer AOS in Cross-Phase Modulation 221
12.4.2.4 Sagnac Interferometer AOS with Optical Amplifier 222
12.4.3 M-Z Interferometer AOS 223
12.4.3.1 M-Z Interferometer AOS with Different Arm Materials 223
12.4.3.2 M-Z Interferometer All-Optical Switch with Different Arm Lengths 224
12.4.4 Ring Resonator AOS 225
12.4.4.1 AOS in M-Z Interferometer Coupled with SCRR 225
12.4.4.2 AOS in DCRR 227
12.4.5 Fiber Grating AOS 229
12.4.5.1 Single Nonlinear FBG AOS 229
12.4.5.2 Single Nonlinear LPFG AOS 231
12.5 Nanoscale AOS 233
12.6 Future Scope and Conclusion 234
Bibliography 235
13 Silicon Photonic Switches 239
Nadir Ali, Mohammad Faraz Abdullah, and Rajesh Kumar
13.1 Introduction 239
13.2 Performance Parameters 239
13.3 Silicon Photonic Platform 240
13.4 Physical Principles for Operation of Switches 241
13.4.1 Electro-optic Effect 242
13.4.2 Carrier Injection/Extraction 242
13.4.3 Thermo-optic Effect 242
13.4.4 All-optical Effect 243
13.5 Major Configurations 244
13.5.1 Directional Coupler 244
13.5.2 Microring Resonator 245
13.5.3 Mach-Zehnder Interferometer 246
13.5.4 Micro-Electro-Mechanical System 247
13.6 Hybrid Silicon Photonic Switches 248
13.6.1 III-V Materials 248
13.6.2 2D Materials 248
13.6.3 Phase Change Materials 249
13.7 Switch Fabrics Using MRR and MZI 252
13.8 Summary 252
Bibliography 252
Part C Application of Optical Switches in Networks 257
14 Switch Control: Bridging the Last Mile for Optical Data Centers 259
Nicola Calabretta and Xuwei Xue
14.1 Introduction 259
14.2 Switch Control Classification 260
14.2.1 Electrical Switch Control 260
14.2.2 Slow Optical Switch Control 261
14.2.3 Fast Optical Switch Control 262
14.3 Challenges for Switch Fabric Control 264
14.3.1 Scalable Control Plane 264
14.3.2 Precise Time Synchronization 265
14.3.3 Fast Burst Clock Data Recovery 266
14.3.4 Lack of Optical Buffer 267
14.3.5 Reliability 268
14.4 Switch Fabric Control: State of the Art 268
14.4.1 Predefined Control 268
14.4.2 SDN Control 268
14.4.3 Label Control 270
14.4.4 AI Control 271
Bibliography 272
15 Reliability in Optical Networks 277
Antony Gratus Varuvel and Rajendra Prasath
15.1 Introduction 277
15.2 RAMS in Optical Networks 278
15.3 Objectives 278
15.4 Life Cycle of a Product/Project 278
15.5 Preamble to RAMS 279
15.5.1 Reliability 280
15.5.2 Availability 281
15.5.3 Maintainability 281
15.5.4 System Safety 281
15.6 Significance of Reliability in Optical Interconnect Systems 282
15.7 Typical Components of Optical Circuitry 282
15.8 Generic Types of Optical System 284
15.8.1 Factors Influencing Reliability in Optical Networks 284
15.8.2 Initial Insight of Failures 284
15.9 Ensuring RAMS for the Optical System 285
15.9.1 Reliability - An Essential Insight 285
15.9.1.1 Typical Reliability Configurations 286
15.9.1.2 Reliability Metrics 287
15.9.1.3 Reliability Apportionment 292
15.9.1.4 Hardware Reliability Prediction 292
15.9.1.5 Software Reliability Prediction 294
15.9.1.6 Derating Analysis 294
15.9.1.7 Stress-Strength Interference Analysis 294
15.9.1.8 Reliability Estimation 295
15.9.1.9 Failure Mode Effects and Criticality Analysis 295
15.9.1.10 Failure Mode Effects Test Cases 296
15.9.1.11 Reliability Assessment/Demonstration 297
15.9.1.12 Human Error Analysis 297
15.9.1.13 Reliability Growth Analysis 297
15.9.1.14 Life Data Analysis 298
15.9.1.15 Physics of Failure 298
15.9.1.16 Design-Cost Trade-off 299
15.9.2 Availability Measures of Optical Networks 299
15.9.2.1 Availability Assessment 299
15.9.2.2 Reliability-Centered Maintenance 300
15.9.2.3 Competing Failure Modes 301
15.9.2.4 Warranty Analysis 301
15.9.2.5 Trend Analysis 302
15.9.3 Maintainability Aspects of Optical Networks 302
15.9.3.1 Maintainability Apportionment 302
15.9.3.2 Maintainability Assessment 303
15.9.3.3 Maintainability Demonstration 303
15.9.3.4 Maintainability Estimation/Evaluation 303
15.9.3.5 Maintainability Prediction 303
15.9.3.6 Maintenance Strategy [Plan/Philosophy] 303
15.9.3.7 Spare Parts Optimization 304
15.9.3.8 Failure Reporting and Corrective Action System 304
15.9.4 Optical Networks for Safety-Critical Applications 304
15.9.4.1 Common Cause Analysis 305
15.9.4.2 Common Mode Analysis 307
15.9.4.3 Fault Tree Analysis 307
15.9.4.4 Functional Hazard Analysis 308
15.9.4.5 Hazard and Operability Studies 308
15.9.4.6 Zonal Safety Analysis 309
15.9.4.7 Particular Risk Assessment 309
15.9.4.8 Software Risk Assessment 309
15.9.4.9 Event Tree Analysis 310
15.10 Process Control in Optical Components 310
15.11 Hardware - Software Interactions (HSI) in Optical Networks 310
15.12 Typical RAMS Realisation Plan for an Optical System 311
15.12.1 System-level RAMS Activities 311
15.12.2 Item-level RAMS Activities 312
15.13 Trade-off Factors of Optical Networks 314
15.14 Some Open Problems in RAMS-Optical System 314
15.15 Conclusion 314
Bibliography 315
16 Protection, Restoration, and Improvement 317
Arighna Basak and Angsuman Sarkar
16.1 Introduction 317
16.2 Objectives of Protection and Restoration 319
16.3 Current Fault Protection and Restoration Techniques 319
16.3.1 Link Protection 320
16.3.2 Path Protection 321
16.3.2.1 Current Fault Protection Techniques 321
16.3.2.2 Path Protection in Mesh Network 321
16.3.2.3 Path Protection in Ring Networks 322
16.3.2.4 OMS Link Protection-OMS-SPRing (Optical Multiplex Section-Shared Protection Ring) 322
16.3.2.5 Ring Loopback 323
16.3.2.6 Current Restoration Techniques 325
16.4 Energy Efficiency of Optical Switching Technology 326
16.5 Signal Quality Monitoring Techniques 327
16.6 Challenges and Recent Research Trends 328
16.7 Conclusion 330
Bibliography 330
17 Optical Switching for High-Performance Computing 335
Rajendra Prasath, Bheemappa Halavar, and Odelu Vanga
17.1 Introduction 335
17.2 Optical Switching 336
17.2.1 Basics of Optical Switching 336
17.2.2 Types of Optical Switching 337
17.2.2.1 Optical Packet Switching 337
17.2.2.2 Circuit Switching 338
17.3 Communication vs Computation 338
17.4 Path Reservation Algorithms 338
17.5 High-Performance Optical Switching and Routing 339
17.5.1 HPC Interconnection Challenges 339
17.5.2 Challenges in the Design of Optical Interconnection Network 340
17.6 Optical Switching Schemes for HPC Applications 340
17.6.1 Routing Scheme (Avoid Packet Loss, Contention, etc.) 341
17.6.1.1 Buffering Schemes 341
17.7 Security Issues in Optical Switching 342
17.7.1 Network Vulnerabilities 342
17.7.1.1 Eavesdropping 342
17.7.2 Jamming Attacks (or Types of Attacks) 343
17.8 Optical Switching - Interesting Topics 344
17.9 Conclusion 344
Bibliography 344
18 Software for Optical Network Modelling 347
Devlina Adhikari
18.1 Optical Networks 347
18.1.1 First Generation of Optical Networks 347
18.1.2 Second Generation of Optical Networks 348
18.1.2.1 Passive Optical Network 349
18.1.2.2 Elastic Optical Network 349
18.1.2.3 Cognitive Optical Network 349
18.1.2.4 Optical Neural Network 350
18.2 Simulation Tools for Planning of Optical Network 350
18.2.1 Network Simulators 350
18.2.1.1 NS-2 350
18.2.1.2 NS-3 351
18.2.1.3 OMNeT++ 351
18.2.1.4 OPNET 352
18.2.2 Physical Layer Simulation 352
18.3 New Technologies 353
18.3.1 Space Division Multiplexing (SDM) 353
18.3.2 Software-Defined Networking (SDN) 353
18.3.3 Artificial Intelligence/Machine Learning (AI/ML) 353
Bibliography 353
Index 359
Introduction
Sandip Nandi1 and Dalia Nandi2
1Department of Electronics and Communication Engineering, Kalyani Government Engineering College, Kalyani, West Bengal, India
2Department of Electronics and Communication Engineering, Indian Institute of Information Technology Kalyani, West Bengal, India
Worldwide demand for enormous information transmission has created an immense need for expansion of capacity for higher generation communication networks. It is predicted that information traffic over the internet will double every year [1]. In this present scenario, Optical networks will be the favored solution to provide enhanced bandwidth for future communication system. Terabytes of information can be transferred between two nodes over the optical links. A switch is embedded in the optical communication system to route the information under the supervision of the control signals. The major limitation for high data communication over an optical link is the use of electronic switches, which will restrict the bandwidth of the link. With the passing of time, optical switches with their improved efficiency and low cost are replacing the traditional electronic switches to overcome the limitations. An optical switch is versatile in nature as it has a large number of usages in communication networks as well as in communication cores of modern-day high configuration computers with data rates of 1000 Gbps. However, the application of optical switches in networks has some of its own challenges in respect of signal impairments and network parameters. This book deals with the present status, advantages, and future developments of optical switches and networks.
This chapter provides a brief introduction to optical communication networks and optical switches. We start the journey with the historical perspective of each topic. Then gradually we provide the essential background, and clarify the key terminologies. Finally we present the organization of the book along with a brief overview of each chapter.
A. Optical Communication Networks
A.1 Historical Perspective
Optical fiber communication has advanced dramatically over the past 50 years due to the enormous advancement of scientific research in the fields of photonics and electronics starting from mid-1970s with the ground-breaking invention of Laser and low-loss optical fiber [2-4]. This advancement is widely reflected in the rate of data transmission increasing from megabits per second over several kilometers for the first ever point-to-point optical fiber connection to terabits per second wavelength division multiplexed optical communication networks. Also there is a continuous increase in productivity in terms of automation, flexibility, capacity, and cost reduction. Table 1 summarizes some significant developments in the progress of optical communication technology over the past few decades.
Today's optical networking shows the broadcast communication networks which can provide increased capacity, routing, and restoration based on recent optical communication technologies. The appreciable increase in capacity using optical networks offers cost reduction for bit transmission compared to other long-haul communication networks (e.g. wireless networks). This has a marvelous societal influence by revolutionizing the internet service. The optical network solution covers the entire transmission network range, from the main hub and metropolitan area network to the access network domain. Backbone networks and metropolitan area networks carry highly aggregated, high-bit-rate data traffic, ranging from the size of cities to entire continents. The access network carries different types of data streams in and out of private and commercial customers, and these data streams are multiplexed /de-multiplexed to the central transmission network in nodes with fixed backhaul connections. The use of the optical network undoubtedly occupies a dominant position in the core and metropolitan area network segments, and recently it has also begun to expand to the access network segment.
Table 1 Historical developments in the field of optical communication technology.
Year Significant developments 1880 Telephone invented by Alexander Graham Bell. 1948 Shannon's Limit described by Claude Shannon [5]. 1957 Principle of Laser described first by Charles Townes and Arthur Schawlow [6]. 1966 Concept of glass fiber with cladding that can carry light without much radiation described by Charles Kao and Hockham. This is the first proposal of optical fiber communication [7]. 1970 First semiconductor lasers made separately by Zhores Alferov at Physical Institute in Leningrad and Mort Panish and Izuo Hayashi at Bell Labs. 1987 First report of erbium-doped optical fiber amplifier by David Payne at the University of Southampton [8]. 1988 First demonstration of soliton transmission over 4,000 km of single-mode fiber by Linn Mollenauer of Bell Labs. 1991 First model based description of erbium-doped optical fiber amplifier by Emmanuel Desurvire and Randy Giles at Bell Labs [9]. 1993 First transmission of data at 10 Gb/s over 280 km of dispersion-managed fiber Andrew Chraplyvy [10]. 1996 Introduction of viable wavelength-division multiplexing (WDM) system. 2002 Nonlinearity compensation in fiber optic transmission was introduced for phase-modulated signals [11]. 2003 ITU-T standardized gigabit-capable passive optical networks. 2009 Experimental demonstration of concept of Superchannel at 1.2 Tb/s [12]. 2010 ITU-T standardized 10-gigabit-capable passive optical networks. 2011 Implementation of spatial multiplexing for optical transport capacity scaling by Peter Winzer [13]. 2012 ITU-T standardized flexible-grid WDM [14]. 2016 ITU-T specification for low-loss low-nonlinearity optical fibers [15]. 2018 Development of low-loss MxN colorless-directionless-contentionless (CDC) wavelength-selective switch (WSS) [16]. 2019 Demonstration of Super-C-band transmission with 6-THz optical bandwidth.The era before 1990 is known for first-generation optical networking, which includes the use of synchronous optical network (SONET/ SDH). This is used as a structure for standardizing line speed, coding technique, bitrate, network elements, and O&M functions. This first-generation network runs on a single wavelength of each optical fiber and is opaque.
During the mid-1990s, a new technology called wavelength division multiplexing (WDM) was proposed and implemented in optical networks, which greatly enhances the capacity of the fiber by providing a technique to transmit dozens of optical signals over a single fiber. It also implements a wavelength routing network through the use of electronic or all-optical switching nodes. This multi-wavelength optical routing scheme establishes the second generation of optical networks. After the introduction of WDM technology, the central backbone and the metropolitan optical network greatly depended on the high-capacity wavelength division multiplexed link, while the traditional networks solely used the fixed capacity link between the nodes of networks with add/drop channels. Minimization of the number of repeaters correlating to minimizing the cost of the network is one of the common criteria for optimization. Hence network planning requires optimization of network design. The International Telecommunications Union (ITU) standardized a set of frequencies from which the wavelength should be chosen for the optimization.
However, due to a change in traffic or link/node failures, the network arrangement may change during the planning phase. Today the implementation of optical add/drop multiplexer and wavelength selective switching technique gives an extra level of opportunity to the execution of network design, permitting the restructuring of connections when there is any change in traffic. This approach has nominal interference with established traffic. In any case, a critical disadvantage actually stays unsettled and this is identified with the idle bandwidth issue because of the coarse and inflexible granularity of the framework.
The key element of the next generation of optical intelligent networks is the control plane, which is responsible for...
