Guided-Wave Optoelectronics

Because integrated optics and optoelectronics technology have been devel­ oping very rapidly during the past few years, significant advances have been made since the first edition of this book was published. Furthermore, interest in the book itself has been strong, leading to a demand for a new, updated version of the text. This has motivated us to issue the present revised pa­ perback edition, whose lower price will make it more easily accessible to researchers in the area and to interested graduate students, in particular. The present edition is essentially similar to the original hardcover book, except that a new chapter (Chap. 7) has been added, which briefly reviews the recent advances in the area and provides new references. Typographical errors spotted in the original edition have also been corrected. Although great care has been exercised, some errors may still occur in the text and other improvements could be introduced in a possible future edition. The volume editor would therefore appreciate any comments from readers, who are urged to communicate their suggestions directly to him.

1. Introduction..- 1.1 Overview.- 1.2 Organization of the Book.- References.- 2. Theory of Optical Waveguides. (With 32 Figures).- 2.1 Ray Optics of the Slab Waveguide.- 2.1.1 Refraction and Reflection.- 2.1.2 Guided Modes.- 2.1.3 The Goos-Hänchen Shift.- 2.1.4 Effective Guide Thickness.- 2.2 Fundamentals of the Electromagnetic Theory of Dielectric Waveguides.- 2.2.1 Maxwell’s Equations.- 2.2.2 Modes of the Waveguide.- 2.2.3 The Wave Equations for Planar Guides.- 2.2.4 Mode Properties Following from Symmetry.- 2.2.5 Orthogonality of the Modes.- 2.2.6 Mode Expansion and Normalization.- 2.2.7 The Variation Theorem for Dielectric Waveguides.- 2.2.8 Power Flow and Stored Energy in a Dielectric Waveguide.- 2.2.9 Variational Properties of the Propagation Constant.- 2.3 Modes of the Planar Slab Guide.- 2.3.1 TE Modes.- 2.3.2 TM Modes.- 2.3.3 Multilayer Slab Guides.- 2.4 Planar Guides with Graded-Index Profiles.- 2.4.1 The Parabolic Profile (Harmonic Oscillator).- 2.4.2 The “1/cosh2” Profile.- 2.4.3 The Exponential Profile.- 2.4.4 Index Profiles with Strong Asymmetry.- 2.4.5 The WKB Method.- 2.5 Channel Waveguides.- 2.5.1 Channel Guide Geometries.- 2.5.2 The Vector Wave Equation.- 2.5.3 Numerical Analysis.- 2.5.4 Separation of Variables.- 2.5.5 The Method of Field Shadows.- 2.5.6 The Vector Perturbation Theorem.- 2.5.7 The Effective-Index Method.- 2.6 Coupled-Mode Formalism and Periodic Waveguides.- 2.6.1 Excitation of Waveguide Modes.- 2.6.2 Waveguide Deformations.- 2.6.3 Coupled-Wave Solutions.- 2.6.4 Periodic Waveguides.- 2.6.5 TE-to-TM Mode Conversion.- References.- 3. Waveguide Transitions and Junctions (With 43 Figures).- 3.1 Waveguide Modes and Coupled-Mode Theory.- 3.1.1 Normal Modes of Coupled Waveguides.- 3.1.2 Coupled-Mode Theory Representation.- 3.2 Fast and Slow Transitions.- 3.2.1 Local Normal Modes.- 3.2.2 Adiabatic Transition.- 3.2.3 Abrupt Transition.- 3.2.4 Tapered Velocity Coupler.- 3.2.5 3 dB Coupler.- 3.2.6 Directional Coupler.- 3.3 Mode Coupling Between Local Normal Modes.- 3.3.1 Coupled-Amplitude Equations.- 3.3.2 Differential Form of Coupled-Amplitude Equations.- 3.3.3 Coupled-Mode Theory Representation of Cij.- 3.4 Two-Arm Branches.- 3.4.1 Step Approximation for a Waveguide Branch.- 3.4.2 Analytic Solution for Shaped Branches.- 3.4.3 Experimental Results.- 3.4.4 Superposition of Solutions.- 3.5 Waveguide Horns.- 3.5.1 Mode-Conversion Coefficient Cij for Channel Waveguides.- 3.5.2 Approximation for ??ij.- 3.5.3 Approximation for Cij.- 3.5.4 Parabolic Solution.- 3.6 Branches with Three Arms.- 3.6.1 Normal Modes of Three Coupled Waveguides.- 3.6.2 3 X 2 Waveguide Coupler.- 3.7 Conclusion.- References.- 4. Titanium-Diffused Lithium Niobate Waveguide Devices (With 39 Figures).- 4.1 Waveguide Fabrication.- 4.1.1 Titanium Diffused Waveguides.- 4.1.2 Proton Exchange LiNbO3 Waveguides.- 4.1.3 Post-Waveguide Processing.- 4.2 Basic Device Considerations.- 4.2.1 Electro-Optic Effect.- 4.2.2 Phase Modulator.- 4.2.3 Insertion Loss.- 4.2.4 Voltage/Loss Tradeoffs: Waveguide Tailoring.- 4.3 Switch/Modulator.- 4.3.1 Directional Coupler.- 4.3.2 Balanced-Bridge Interferometer.- 4.3.3 Intersecting-Waveguide Switch.- 4.4 On/Off Modulators.- 4.4.1 Y-Branch Interferometer.- 4.4.2 Voltage and Bandwidth Consideration for Switch/ Modulators.- 4.5 Polarization Devices.- 4.5.1 TE — TM Conversion.- 4.5.2 Polarization Controller.- 4.5.3 Polarization-Selective Devices.- 4.6 Wavelength Filters.- 4.6.1 Interferometric Filters.- 4.6.2 Coupled-Mode Filters.- 4.7 Polarization-Insensitive Devices.- 4.8 Some Ti:LiNbO3 Integrated-Optic Circuits.- 4.8.1 Coherent Lightwave Receiver.- 4.8.2 Optical Switch Arrays.- 4.9 Applications.- 4.9.1 External Modulators.- 4.9.2 High-Speed Analog to Digital Conversion.- 4.9.3 Fiber Gyroscope Chip.- References.- 5. Mode-Controlled Semiconductor Lasers (With 55 Figures).- 5.1 Organization of the Chapter.- 5.1.1 Notation.- 5.2 Laser Basics.- 5.2.1 Epitaxial Materials and Heterostructure.- 5.2.2 Waveguide Propagation, Amplification and Oscillation.- 5.2.3 Laser Gain.- 5.2.4 Spontaneous Emission.- 5.2.5 Photon Rate Equation.- 5.2.6 Spectral Hole Burning.- 5.2.7 Carrier Injection in a Heterojunction.- 5.2.8 Modal Rate Equations.- 5.2.9 Longitudinal Variation of Photon Density.- 5.2.10 Steady-State Solution of Rate Equations.- 5.2.11 Measurement of Modal Reflectivity and Laser Gain.- 5.3 Structures for Transverse-Mode Control.- 5.3.1 Stripe Geometry Laser, Blocking Layer.- 5.3.2 Buried Heterostructure Lasers.- 5.3.3 Ridge Waveguide Lasers.- 5.4 Longitudinal Mode Control.- 5.4.1 Three- and Four-Mirror Resonators.- 5.4.2 Distributed Bragg Gratings.- 5.4.3 Semiconductor DFB Lasers.- 5.4.4 DBR and Phase-Slip DFB Lasers.- 5.5 Linewidth.- 5.5.1 Linewidth of Fabry-Perot Laser.- 5.5.2 Linewidth Reduction Using Extended Cavities.- 5.6 High-Speed Modulation.- 5.6.1 Modulation Response.- 5.6.2 Origin of Chip Parasitics.- 5.6.3 Evaluation of Parasitics.- 5.6.4 Dependence of Parasitics on Device Structure.- 5.6.5 The Intrinsic Laser — Small-Signal Intensity Modulation Response.- 5.6.6 High-Frequency Limitations.- 5.6.7 Design Considerations for Wideband Lasers.- 5.6.8 Large-Signal Modulation — PCM.- 5.6.9 Large-Signal Modulation — Gain Switching.- 5.6.10 Active Mode-Locking.- 5.7 Luminescent Diodes and Laser Amplifiers.- 5.7.1 Edge-Emitting and Superluminescent Diodes.- 5.7.2 Linear Amplification and Amplified Spontaneous Emission in TWAs and ELEDs.- 5.7.3 Fabry-Perot Amplifiers and ELEDs.- 5.7.4 Amplifier Gain Compression.- 5.7.5 Receiver Noise.- 5.8 Tunable and FM Lasers.- 5.8.1 Tunable DBR.- 5.8.2 Tunable DFB.- Appendix 5A: Glossary of Symbols.- References.- 6. Semiconductor Integrated Optic Devices (With 66 Figures).- 6.1 Semiconductor Waveguide Theory.- 6.1.1 Methods of Index Change in Semiconductors.- 6.1.2 Slab Waveguides.- 6.1.3 Channel Waveguides.- 6.1.4 Coupling Effects.- 6.1.5 Optical Loss.- 6.1.6 Curvature Loss.- 6.2 Material Technology.- 6.2.1 Liquid Phase Epitaxy (LPE).- 6.2.2 Vapor Phase Epitaxy (VPE).- 6.2.3 Metal Organic Chemical Vapor Deposition (MOCVD).- 6.2.4 Molecular Beam Epitaxy (MBE).- 6.2.5 Summary.- 6.3 Passive Waveguide Devices — Fabrication and Characterization.- 6.3.1 Channel Waveguides.- 6.3.2 Couplers.- 6.3.3 Bends and Branches.- 6.3.4 Grating Filter.- 6.4 Electro-Optic Guided-Wave Modulators — Theory.- 6.4.1 Electro-Optic Effect in III—V Semiconductors.- 6.4.2 Modulator Design.- 6.4.3 Modulation Frequency Analysis.- 6.4.4 Traveling-Wave Phase Modulators.- 6.4.5 TE-TM Coupling Analysis.- 6.4.6 Infrared Waveguide Modulators — Wavelength Scaling.- 6.4.7 Electro-Absorption Modulation.- 6.4.8 Carrier-Injection Modulator.- 6.4.9 Nonlinear Waveguide Modulator.- 6.5 Electro-Optic Guided-Wave Modulator Characteristics.- 6.5.1 Phase Modulators.- 6.5.2 Directional-Coupler Switches.- 6.5.3 Interferometric Modulators.- 6.5.4 Integrated Waveguides/Optoelectronics/Electronics.- 6.5.5 Electro-Absorption Modulators.- 6.5.6 Multiple-Quant urn-Well Modulators.- 6.5.7 Nonlinear Waveguide Modulators.- 6.6 Optoelectronic Integrated Circuits (OEIC).- 6.7 Concluding Remarks.- References.- 7. Recent Advances (With 1 Figure).- 7.1 Introduction.- 7.2 Theory of Optical Waveguides.- 7.3 Waveguide Transitions and Junctions.- 7.4 Titanium-Diffused Lithium Niobate Waveguide Devices.- 7.5 Mode-Controlled Semiconductor Lasers.- 7.6 Semiconductor Integrated Optic Devices.- References.