This book describes the latest development in optical fiber devices, and their applications to sensor technology. Optical fiber sensors, an important application of the optical fiber, have experienced fast development, and attracted wide attentions in basic science as well as in practical applications. Sensing is often likened to human sense organs. Optical fiber can not only transport information acquired by sensors at high speed and large volume, but also can play the roles of sensing element itself. Compared with electric and other types of sensors, fiber sensor technology has unique merits. It has advantages over conventional bulky optic sensors, such as combination of sensing and signal transportation, smaller size, and possibility of building distributed systems. Fiber sensor technology has been used in various areas of industry, transportation, communication, security and defense, as well as daily life. Its importance has been growing with the advancement of the technology and the expansion of the scope of its application, a growth this book fully describes.

ZUJIE FANG is a Professor at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences.

KEN K. CHIN is a Professor of Physics at the New Jersey Institute of Technology. His research interests include infrared imaging sensing and device physics.

RONGHUI QU is a Professor at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences.

HAIWEN CAI is a Professor at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences.

Klappentext

Explains the physical principles of optical fiber sensors and makes their practical applications readily and easily accessible

This all-encompassing book provides a systematic treatment of optical fiber sensors, presenting the subject from every angle with great breadth and detail, offering readers a deep and well-rounded understanding of the technology and its expanding applications.

Fundamentals of Optical Fiber Sensors begins with basic physical principles, progresses to sensing mechanisms, and moves on to take an in-depth look at applications. Emphasizing the structure and optical characteristics of optical fiber sensors, it employs clear figures and fundamental formulas to explain their mechanisms. Featuring a summary of the basics and tools at the end of each chapter, extensive references, and a comprehensive subject index, this unique and timely guide:

• Reviews the essential principles of optical fiber, including the electromagnetic theory and ray optics
• Explains fiber sensitivities and fiber devices
• Describes fiber gratings of various structures and their applications in sensor technology
• Explores distributed fiber sensors, based on elastic and inelastic optical scatterings in fibers
• Introduces fiber sensors with special applications, including fiber gyroscopes, fiber hydrophones, Faraday effect sensors, and sensors based on surface plasmon
• Examines extrinsic fiber Fabry-Perot interferometer sensors

Fundamentals of Optical Fiber Sensors is an excellent introduction to this topic for senior undergraduates and graduate students as well as a convenient reference for scientists and engineers working in the field.

Inhalt

Preface xi

1 Introduction 1

1.1 Historical Review and Perspective 1

1.2 Classifications of Optical Fiber Sensors 3

1.3 Overview of the Chapters 6

References 8

2 Fundamentals of Optical Fibers 10

2.1 Introduction to Optical Fibers 10

2.1.1 Basic Structure and Fabrication of Optical Fiber 10

2.1.2 Basic Characteristics 12

2.1.3 Classifications of Optical Fibers 17 2.2 Electromagnetic Theory of Step-Index Optical Fibers 18

2.2.1 Maxwell Equations in Cylindrical Coordinates 19

2.2.2 Boundary Conditions and Eigenvalue Equations 23

2.2.3 Weakly Guiding Approximation, Hybrid Modes, and Linear Polarized Modes 26

2.2.4 Field Distribution and Polarization Characteristics 29

2.2.5 Multimode Fiber and Cladding Modes 35

2.2.6 Propagation of Optical Pulses in Optical Fibers 39

2.3 Basic Theory of the Gradient-Index Optical Fiber 42

2.3.1 Ray Equation in Inhomogeneous Media 42

2.3.2 Ray Optics of GRIN Fiber 46

2.3.3 Wave Optics of GRIN Fiber 51

2.3.4 Basic Characteristics of Gradient Index Lens 56

2.4 Special Optical Fibers 57

2.4.1 Rare-Earth-Doped Fibers and Double-Cladding Fibers 57

2.4.2 Polarization Maintaining Fibers 60

2.4.3 Photonic Crystal Fiber and Microstructure Fiber 64

Problems 69

References 71

3 Fiber Sensitivities and Fiber Devices 76

3.1 Fiber Sensitivities to Physical Conditions 76

3.1.1 Sensitivity to Axial Strain 77

3.1.2 Sensitivity to Lateral Pressure 78

3.1.3 Bending-Induced Birefringence 83

3.1.4 Torsion-Induced Polarization Mode Cross-Coupling 87

3.1.5 Bending Loss 91

3.1.6 Vibration and Mechanical Waves in Fiber 95

3.1.7 Sensitivity to Temperature 96

3.2 Fiber Couplers 97

3.2.1 Structures and Fabrications of 2×2 Couplers 98

3.2.2 Basic Characteristics and Theoretical Analyses of the Coupler 99

3.2.3 N×N and 1×N Fiber Star Couplers 110

3.2.4 Coupling in Axial Direction and Tapered Fiber 114

3.3 Fiber Loop Devices Incorporated with Couplers 118

3.3.1 Fiber Sagnac Loops 118

3.3.2 Fiber Rings 126

3.3.3 Fiber MachZehnder Interferometers and Michelson Interferometers 131

3.3.4 Fiber Loops Incorporated with 3×3 Couplers 135

3.4 Polarization Characteristics of Fibers 142

3.4.1 Polarization State Evolution in Fibers 142

3.4.2 Basic Characteristics of Polarization Mode Dispersion 154

3.4.3 Spun Fiber and Circular Birefringence Fiber 157

3.4.4 Faraday Rotation and Optical Activity 159

3.5 Fiber Polarization Devices 162

3.5.1 Fiber Polarizers 162

3.5.2 Fiber Polarization Controller 165

3.5.3 Fiber Depolarizer and Polarization Scrambler 166

3.5.4 Fiber Optical Isolator and Circulator 170

Problems 172

References 174

4 Fiber Gratings and Related Devices 183

4.1 Introduction to Fiber Gratings 183

4.1.1 Basic Structure and Principle 183

4.1.2 Photosensitivity of Optical Fiber 186

4.1.3 Fabrication and Classifications of Fiber Gratings 190

4.2 Theory of Fiber Grating 194

4.2.1 Theory of Uniform FBG 194

4.2.2 Theory of Long-Period Fiber Grating 202

4.2.3 Basic Theory of Nonuniform Fiber Gratings 208

4.2.4 Inverse Engineering Design 214

4.2.5 Apodization of Fiber Grating 219

4.3 Special Fiber Grating Devices 222

4.3.1 Multisection FBGs 222

4.3.2 Chirped Fiber Bragg Grating 233

4.3.3 Tilted Fiber Bragg Gratings 236

4.3.4 Polarization Maintaining Fiber Gratings 243

4.3.5 In-Fiber Interferometers and Acoustic Optic Tunable Filter 246

4.4 Fiber Grating Sensitivities and Fiber Grating Sensors 249

4.4.1 Sensitivities of Fiber Gratings 250