Fiber Bragg Gratings

• Provides an overview of Fiber Bragg Gratings (FBGs), from fundamentals to applications
• Evaluates the advantages and disadvantages of particular applications, methods and techniques
• Contains new chapters on sensing, femtosecond laser writing of FBGs and poling of glass and optical fibers
• Includes a special version of the photonic simulator PicWave(tm), allowing the reader to make live simulations of many of the example devices presented in the book.

This fully revised, updated and expanded second edition covers the substantial advances in the manufacture and use of FBGs in the years since the publication of the pioneering first edition. It presents a comprehensive treatise on FBGs and addresses issues such as the merits of one solution over another; why particular fabrication methods are preferred; and what advantages a user may gain from certain techniques.

Beginning with the principles of FBGs, the book progresses to discuss photosensitization of optical fibers, Bragg grating fabrication and theory, properties of gratings, specific applications, sensing technology, glass poling, advances in femtosecond laser writing of Bragg gratings and FBG measurement techniques. In addition to material on telecommunications usage of FBGs, application areas such as fiber lasers and sensors are addressed in greater detail.

This special version of Picwave is limited to modelling only the passive fibre devices covered in this book. However the full PicWave package is capable of modelling other non-linear and active devices such as laser diodes and SOAs as discussed in Chapter 8. More information about PicWave can be found at www.photond.com/products/picwave.htm.

In addition to researchers, scientists, and graduate students, this book will be of interest to industrial practitioners in the field of fabrication of fiber optic materials and devices.

Raman Kashyap, Canada Research Chair holder on Future Photonics Systems, and Professor at École Polytechnique, University of Montréal since 2003, has researched optical fibers and devices for over 30 years. He pioneered the fabrication of FBGs and applications in telecommunications and photonics.

• Provides an overview of Fiber Bragg Gratings (FBGs), from fundamentals to applications
• Evaluates the advantages and disadvantages of particular applications, methods and techniques
• Contains new chapters on sensing, femtosecond laser writing of FBGs and poling of glass and optical fibers
• Includes a special version of the photonic simulator PicWave(tm), allowing the reader to make live simulations of many of the example devices presented in the book.

Photonics engineers, optical fiber designers, sensor industry manufacturers, engineers developing optical sensors, communications engineers, students, researchers, professors

1 Introduction

1.1 Historical Perspective
1.2 Materials for Glass Fibers
1.3 Origins of the Refractive Index of Glass
1.4 Overview of Chapters

2 Photosensitivity and Photosensitization of Optical Fibers

2.1 Photorefractivity and Photosensitivity
2.2 Defects in Glass
2.3 Detection of Defects
2.4 Photosensitization Techniques
2.5 Densification and Stress in Fibers
2.6 Summary of Photosensitive Mechanisms in Germanosilicate Fibers
2.7 Summary of Routes to Photosensitization
2.8 Chemical Composition Gratings

3 Fabrication of Bragg Gratings

3.1 Methods for Fiber Bragg Grating Fabrication
3.2 Tunable Phase Masks
3.3 Type II Gratings
3.4 Type IIA Gratings
3.5 Sources for Holographic Writing of Gratings

4 Theory of Fiber Bragg Gratings

4.1 Wave Propagation
4.2 Coupled-Mode Theory
4.3 Coupling of Counterpropagating Guided Modes
4.4 Codirectional Coupling
4.5 Polarization Couplers: Rocking Filters
4.6 Properties of Uniform Bragg Gratings
4.7 Radiation Mode Couplers
4.8 Grating Simulation
4.9 Multilayer Analysis
4.10 Grating Design

5 Apodization of Fiber Gratings 189

5.1 Apodization Shading Functions 190
5.2 Basic Principles and Methodology 193
5.3 Fabrication Requirements for Apodization and Chirp 212

6 Fiber Grating Band-Pass Filters

6.1 Distributed Feedback, Fabry–Perot, Superstructure, and Moire Gratings
6.2 The Fabry–Perot and Moire´ Band-Pass Filters
6.3 The Michelson Interferometer Band-Pass Filter
6.4 The Mach–Zehnder Interferometer Band-Pass Filter
6.5 The Optical Circulator-Based OADM
6.6 The Polarizing Beam Splitter Band-Pass Filter
6.7 In-Coupler Bragg Grating Filters
6.8 Side-Tap and Long-Period Grating Band-Pass Filters
6.9 Polarization Rocking Band-Pass Filter
6.10 Mode Converters
6.11 Sagnac Loop Interferometer
6.12 Gires–Tournois Filters
6.13 Tunable Band-Pass Filters
6.14 LPG Filters

7 Chirped Fiber Bragg Gratings

7.1 General Characteristics of Chirped Gratings
7.2 Chirped and Step-Chirped Gratings
7.3 Super-Step-Chirped Gratings
7.4 Polarization Mode Dispersion in Chirped Gratings
7.5 Systems Measurements with DCGs
7.6 Other Applications of Chirped Gratings

8 Fiber Grating Lasers and Amplifiers

8.1 Fiber Grating Semiconductor Lasers: The FGSL
8.2 Static and Dynamic Properties of FGLs
8.3 The Fiber Bragg Grating Rare-Earth-Doped Fiber Laser
8.4 Erbium-Doped Fiber Lasers
8.5 The Distributed Feedback Fiber Laser
8.6 Bragg Grating-Based Pulsed Sources
8.7 Fiber Grating Resonant Raman Amplifiers
8.8 Gain-Flattening and Clamping in Fiber Amplifiers
8.9 High-Powered Lasers and Amplifiers
8.10 Toward Higher-Power Fiber Lasers and Amplifiers
8.11 Ultrahigh-Power Lasers and Amplifiers

9 Measurement and Characterization of Gratings

9.1 Measurement of Reflection and Transmission Spectra of Bragg Gratings
9.2 Perfect Bragg Gratings
9.3 Phase and Temporal Response of Bragg Gratings
9.4 Strength, Annealing, and Lifetime of Gratings

10 Principles of Optical Fiber Grating Sensors

10.1 Sensing with Fiber Bragg Gratings
10.2 Evanescent-Field Refractive Index Sensors
10.3 Long-Period Grating (LPG) Sensors
10.4 Applications of FBG Sensors
10.5 Conclusions and Future Prospects

11 Femtosecond-Induced Refractive Index Changes in Glass

11.1 Light Propagation in Glass
11.2 Conclusion

12 Poling of Glasses and Optical Fibers

12.1 Optical Poling
12.2 UV Poling
12.3 Thermal Poling of Glass
12.4 Characterization Techniques
12.5 Fundamental and Practical Issues
12.6 The Poling Process in Detail
12.7 Routes for Increasing the Second-Order Optical Nonlinearity
12.8 Poled Films and Waveguides
12.9 Poled Fibers
12.10 Conclusions