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Series Preface xiii Preface xv
1. Introduction 1
1.1 Definition of Glassy States 1
1.2 The Glassy State and Glass Transition Temperature (Tg) 1
1.3 Kauzmann Paradox and Negative Change in Entropy 4
1.4 Glass-Forming Characteristics and Thermodynamic Properties 5
1.5 Glass Formation and Co-ordination Number of Cations 14
1.6 Ionicity of Bonds of Oxide Constituents in Glass-Forming Systems 20
1.7 Definitions of Glass Network Formers, Intermediates and Modifiers and Glass-Forming Systems 23
1.7.1 Constituents of Inorganic Glass-Forming Systems 24
1.7.2 Strongly Covalent Inorganic Glass-Forming Networks 26
1.7.3 Conditional Glass Formers Based on Heavy-Metal Oxide Glasses 29
1.7.4 Fluoride and Halide Network Forming and Conditional Glass-Forming Systems 31
1.7.5 Silicon Oxynitride Conditional Glass-Forming Systems 36
1.7.6 Chalcogenide Glass-Forming Systems 37
1.7.7 Chalcohalide Glasses 45
1.8 Conclusions 46 Selected Biography 46 References 46
2. Glass Structure, Properties and Characterization 51
2.1 Introduction 51
2.1.1 Kinetic Theory of Glass Formation and Prediction of Critical Cooling Rates 51
2.1.2 Classical Nucleation Theory 52
2.1.3 Non-Steady State Nucleation 54
2.1.4 Heterogeneous Nucleation 55
2.1.5 Nucleation Studies in Fluoride Glasses 56
2.1.6 Growth Rate 58
2.1.7 Combined Growth and Nucleation Rates, Phase Transformation and Critical Cooling Rate 59
2.2 Thermal Characterization using Differential Scanning Calorimetry (DSC) and Differential Thermal Analysis (DTA) Techniques 62
2.2.1 General Features of a Thermal Characterization 62
2.2.2 Methods of Characterization 63
2.2.3 Determining the Characteristic Temperatures 64
2.2.4 Determination of Apparent Activation Energy of Devitrification 66
2.3 Coefficients of Thermal Expansion of Inorganic Glasses 68
2.4 Viscosity Behaviour in the near-Tg, above Tg and in the Liquidus Temperature Ranges 71
2.5 Density of Inorganic Glasses 75
2.6 Specific Heat and its Temperature Dependence in the Glassy State 76
2.7 Conclusion 77 References 77
3. Bulk Glass Fabrication and Properties 79
3.1 Introduction 79
3.2 Fabrication Steps for Bulk Glasses 80
3.2.1 Chemical Vapour Technique for Oxide Glasses 80
3.2.2 Batch Preparation for Melting Glasses 81
3.2.3 Chemical Treatment Before and During Melting 81
3.3 Chemical Purification Methods for Heavier Oxide (GeO2 and TeO2) Glasses 84
3.4 Drying, Fusion and Melting Techniques for Fluoride Glasses 87
3.4.1 Raw Materials 88
3.4.2 Control of Hydroxyl Ions during Drying and Melting of Fluorides 88
3.5 Chemistry of Purification and Melting Reactions for Chalcogenide Materials 91
3.6 Need for Annealing Glass after Casting 96
3.7 Fabrication of Transparent Glass Ceramics 97
3.8 Sol-Gel Technique for Glass Formation 99
3.8.1 Background Theory 99
3.8.2 Examples of Materials Chemistry and Sol-Gel Forming Techniques 103
3.9 Conclusions 105 References 105
4. Optical Fibre Design, Engineering, Fabrication and Characterization 109
4.1 Introduction to Geometrical Optics of Fibres: Geometrical Optics of Fibres and Waveguides (Propagation, Critical and Acceptance Angles, Numerical Aperture) 109
4.2 Solutions for Dielectric Waveguides using Maxwell''s Equation 114
4.2.1 Analysis of Mode Field Diameter in Single Mode Fibres 115
4.3 Materials Properties Affecting Degradation of Signal in Optical Waveguides 117
4.3.1 Total Intrinsic Loss 117
4.3.2 Electronic Absorption 118
4.3.3 Experimental Aspects of Determining the Short Wavelength Absorption 121
4.3.4 Scattering 121
4.3.5 Infrared Absorption 124
4.3.6 Characterization of Vibrational Structures using Raman and IR Spectroscopy 126
4.3.7 Experimental Aspects of Raman Spectroscopic Technique 127
4.3.8 Fourier Transform Infrared (FTIR) spectroscopy 128
4.3.9 Examples of the Analysis of Raman and IR spectra 130
4.4 Fabrication of Core-Clad Structures of Glass Preforms and Fibres and their Properties 141
4.4.1 Comparison of Fabrication Techniques for Silica Optical Fibres with Non-silica Optical Fibres 143
4.4.2 Fibre Fabrication using Non-silica Glass Core-Clad Structures 151
4.4.3 Loss Characterization of Fibres 153
4.5 Refractive Indices and Dispersion Characteristics of Inorganic Glasses 158
4.5.1 Experimental Procedure for Measuring Refractive Index of a Glass or Thin Film 163
4.5.2 Dependence of Density on Temperature and Relationship with Refractive Index 166
4.5.3 Effect of Residual Stress on Refractive Index of a Medium and its Effect 169
4.6 Conclusion 170 References 170
5. Thin-film Fabrication and Characterization 178
5.1 Introduction 178
5.2 Physical Techniques for Thick and Thin Film Deposition 179
5.3 Evaporation 179
5.3.1 General Description 179
5.3.2 Technique, Materials and Process Control 179
5.4 Sputtering 181
5.4.1 Principle of Sputtering 181
5.5 Pulsed Laser Deposition 183
5.5.1 Introduction and Principle 183
5.5.2 Process 184
5.5.3 Key Features of PLD process 186
5.5.4 Controlling Parameters and Materials Investigated 187
5.5.5 Fabrication of Thin Film Structures using PLD and Molecular Beam Epitaxy 188
5.6 Ion Implantation 192
5.6.1 Introduction 192
5.6.2 Technique and Structural Changes 192
5.6.3 Governing Parameters for Ion Implantation 193
5.6.4 Materials Systems Investigated 194
5.7 Chemical Techniques 194
5.7.1 Characteristics of Chemical Vapour Deposition Processes 195
5.7.2 Materials System Studied and Applications 196
5.7.3 Molecular Beam Epitaxy (MBE) 196
5.8 Ion-Exchange Technique 197
5.9 Chemical Solution or Sol-Gel Deposition (CSD) 200
5.9.1 Introduction 200
5.9.2 CSD Technique and Materials Deposited 202
5.10 Conclusion 203 References 203
6. Spectroscopic Properties of Lanthanide (Ln3+) and Transition Metal (M3+)-Ion Doped Glasses 209
6.1 Introduction 209
6.2 Theory of Radiative Transition 209
6.3 Classical Model for Dipoles and Decay Process 212
6.4 Factors Influencing the Line Shape Broadening of Optical Transitions 214
6.5 Characteristics of Dipole and Multi-Poles and Selection Rules for Optical Transitions: 218
6.5.1 Analysis of Dipole Transitions Based on Fermi''s Golden Rule 219
6.5.2 Electronic Structure and Some Important Properties of Lanthanides 221
6.5.3 Laporte Selection Rules for Rare-Earth and Transition Metal Ions 224
6.6 Comparison of Oscillator Strength Parameters, Optical Transition Probabilities and Overall Lifetimes of Excited States 227
6.6.1 Radiative and Non-Radiative Rate Equation 231
6.6.2 Energy Transfer and Related Non-Radiative Processes 233
6.6.3 Upconversion Process 237
6.7 Selected Examples of Spectroscopic Processes in Rare-Earth Ion Doped Glasses 238
6.7.1 Spectroscopic Properties of Trivalent Lanthanide (Ln3+)-Doped Inorganic Glasses 239
6.7.2 Brief Comparison of Spectroscopic Properties of Er3+-Doped Glasses 241
6.7.3 Spectroscopic Properties of Tm3+-Doped Inorganic Glasses 247
6.8 Conclusions 257 References 257
7. Applications of Inorganic Photonic Glasses 261
7.1 Introduction 261
7.2 Dispersion in Optical Fibres and its Control and Management 261
7.2.1 Intramodal Dispersion 262
7.2.2 Intermodal Distortion 265
7.2.3 Polarization Mode Dispersion (PMD) 266
7.2.4 Methods of Controlling and Managing Dispersion in Fibres 267
7.3 Unconventional Fibre Structures 269
7.3.1 Fibres with Periodic Defects and Bandgap 269
7.3.2 TIR and Endlessly Single Mode Propagation in PCF with Positive Core-Cladding Difference 272
7.3.3 Negative Core-Cladding Refractive Index Difference 272
7.3.4 Control of Group Velocity Dispersion (GVD) 273
7.3.5 Birefringence in Microstructured Optical Fibres 274
7.4 Optical Nonlinearity in Glasses, Glass-Ceramics and Optical Fibres 275
7.4.1 Theory of Harmonic Generation 275
7.4.2 Nonlinear Materials for Harmonic Generations and Parametric Processes 279
7.4.3 Fibre Based Kerr Media and its Application 285
7.4.4 Resonant Nonlinearity in Doped Glassy Hosts 287
7.4.5 Second Harmonic Generation in Inorganic Glasses 288
7.4.6 Electric-Field Poling and Poled Glass 289
7.4.7 Raman Gain Medium 291
7.4.8 Photo-induced Bragg and Long-Period Gratings in Fibres 292
7.5 Applications of Selected Rare-earth ion and Bi-ion Doped Amplifying Devices 294
7.5.1 Introduction 294
7.5.2 Examples of Three-Level or Pseudo-Three-Level Transitions 296
7.5.3 Examples of Four-Level Laser Systems 300
7.6 Emerging Opportunities for the Future 302
7.7 Conclusions 303 References 304 Supplementary References 311 Symbols and Notations Used 315 Index 317