Table of Contents

Abstract   1

1 Introduction   7

1.1 All-Optical Components in Future Terabit-Per-Second Telecommunication Systems 8
            1. Progress towards Terabit-Per-Second Transmissions 8
            2. WDM/OTDM Enabling Technologies 10
            3. Conclusions 12

1.2 From Early to State-of-the-Art All-Optical Devices  13
            1. Different Nonlinear Materials 13
            2. Techniques to Exploit the Nonlinearities 15
            3. Configurations 18

1.3 Outline  24

1.4 References  26

2.1 Optical Nonlinearities   36
            1. The Wave Equation for Nonlinear Optical Media 36
            2. Solutions of the Nonlinear Wave Equation 37
            3. Kramers-Krönig Relations in Nonlinear Optics 39
            4. Nonlinear Effects 40
            5. Time Regimes of Nonlinear Effects 56
            6. Qualitatively Calculated Refractive-Index Changes under  Control-Signal Injections 59
            7. Concluding Remarks on XPM All-Optical Devices 60

2.2 The Semiconductor Optical Amplifier Equations  61
            1. Introductory Definitions 61
            2. The Propagation of an Amplified Signal in an SOA 65
            3. A More Complete Solution 68

2.3 The MZI-SOA Transfer Functions  71

2.4 References  75

            3.1 Material Gain  82
                        1. Introduction 82
                        2. Structures and Devices 83
                        3. Material-Gain Characterisation 84
                        4. Comparison of Experiment with Theory 91
                        5. Differential Material Gain dgm/dN and dgm/dT 92

3.2 Refractive-Index Changes  95
            1. Measurement of the Refractive-Index Changes 95
            2. Effective Group Refractive Index 102

3.3 Alpha Factors  103
            1. Introduction 103
            2. Experiments on a_N 104
            3. Experiments on a_T 106

3.4 Parametrizations of the Material Parameters  108
            1. Material-Gain Parametrization 108
            2. Internal-Loss Parametrization 112
            3. Refractive-Index-Change Parametrization 113
            4. Alpha Factor Parametrization 114

3.5 Appendix  115
            1. Temperature Correction 115
            2. Current <-> Carrier-Density Relations 117
            3. Output-Power 119

3.6 References  121

4.1 Summary of Multimode-Interference Theory  126
            1. Self Images and the Term Multimode Interference 126
            2. Classification of MMIs  127

4.2 Design Guidelines for MMIs  132
            1. MMI Widths and MMI Lengths 132
            2. Trap Waveguides 135

4.3 Guided Wave 1.30/1.55 mm WDMs based on MMI  136
            1. Introduction 136
            2. MMI-WDMs 137
            3. Experiments 143
            4. Future Applications as MMI-WDM Add-Drop Switches 145

4.4 Multimode Interference Couplers for the Conversion and Combining of Zero and First Order Modes   147
            1. Introduction 147
            2. Principles of MMI-Converter-Combiners 148
            3. Power-Splitter for Zero and First Order Modes 157
            4. Experiment 161
            5. Conclusions 166
            6. Appendix: Generalisation of the Concept to Converter-Combiner MMIs with K outputs 167

4.5 Spatial Mode Filters realized with Multi-Mode Interference Couplers  170
            1. Introduction 170
            2. Principle of MMI-Filters 171
            3. Experiment 173
            4. Conclusions 176

4.6 Optical Bandwidths and Design Tolerances of Multimode-Interference Converter-Combiners   177
            1. Introduction 177
            2. Theory  178
            3. Comparison with Mode Analysis and Experiment 181
            4. Conclusions 185
            5. Appendix 186
            4.7 References  188

5.1 Extinction-Ratio Limitations in All-Optical Devices  194

5.2 All-Optical Space Switches with Gain and Ideal Extinction-Ratios  196
            1. Introduction 196
            2. Basic MZI-SOA All-Optical Switch 197
            3. Analysis      199
            4. Specific MZI-SOA Implementations 204
            5. Experiments  214
            6. Conclusions 218

5.3 References  222

6.1 All-Optical MZI Wavelength Converters and Switches with Integrated Data- and Control-Signal Separation Scheme   226
            1. Introduction 226
            2. Co- and Counter-Propagating Operation with Versatile All-Optical Devices  228
            3. All-Optical Control- And Data-Signal Separation Schemes 230
            4. Static and Dynamic Characterizations 236
            5. Conclusions 248

6.2 Polarization Independent Optical Phase Conjugation with Pump-Signal Filtering in a Monolithically Integrated MZI-SOA configuration 249
            1. Introduction 249
            2. Configuration 250
            3. Experiments 251

6.3 References  256

            7.1 Conclusions  262

            7.2 Outlook  264

Appendix   265

    App. A  Material Gain   266
    App. B  Nonlinear Gain Compression  273
    App. C  InGaAsP Material Parameters  276
    App. D  Material Parameters Used in the Calculations  280
    App. E  Useful Formulas  281
    App. F  List of Symbols and Acronyms  283

Curriculum Vitae   293

Index   295