Monolithic Diode-Laser Arrays

Although semiconductor-diode lasers are the most compact, highest gain and most efficient laser sources, difficulties remain in developing structures that will produce high-quality, diffraction-limited output beams. Indeed, only a few designs have emerged with the potential for producing high-power, high-brightness monolithic sources. This book presents and analyzes the results of work performed over the past two decades in the development of such diode-laser arrays.

Contenu

1. Introduction and Background.- 1.1 History of Diode-Laser Array Development.- 1.2 Nonsemiconductor Laser Arrays.- 1.3 Contributing Factors to Developing Monolithic Diode-Laser Arrays.- 1.3.1 Key Technological Advances.- 1.3.2 Performance Limitations of Single-Element Diode Lasers.- 1.3.3 Distinction Between Coherent and Incoherent Diode-Laser Arrays.- 1.3.4 Applications for Diode-Laser Arrays.- 1.4 Design Concepts for Coherent Diode-Laser Arrays.- 1.4.1 Laterally Coupled Diode-Laser Array Concepts.- 1.4.2 Longitudinally Coupled Diode-Laser Array Concepts.- 1.4.3 Output Coupling Mechanisms.- 2. Fundamentals of High-Power Operation.- 2.1 Threshold Characteristics.- 2.2 Current-Gain Properties.- 2.3 Optimizing Operation Above-Threshold.- 2.3.1 Differential Quantum Efficiency.- 2.3.2 Conversion Efficiency.- 2.3.3 Maximizing Conversion Efficiency.- 2.3.4 Nonlinear Gain Saturation and Conversion Efficiency.- 2.3.5 Maximizing Power-Extraction Efficiency.- 2.3.6 Efficiency and Power-Current Characteristics: Nonlinear Calculation.- 2.4 Scaling Properties of Semiconductor and Non-Semiconductor Lasers.- 2.5 Scaling Limitations on Power Performance of Diode Lasers.- 2.6 Effect of Carriers on Optical Properties.- 2.7 Linewidth Broadening Factor.- 2.8 Thermal Effects in High-Power Arrays.- 2.8.1 Effect of Heating on Diode-Laser Characteristics.- 2.8.2 Heat Dissipation in Diode-Laser Arrays.- 2.8.3 Thermal Management and Performance Limitations.- 3. Spatial and Spectral Mode Discrimination.- 3.1 Spatial Modes of Planar Semiconductor Waveguides.- 3.1.1 Index Guiding.- 3.1.2 Gain Guiding.- 3.1.3 Mixed Guiding.- 3.1.4 Parabolic Dielectic-Profile Waveguide Model.- 3.2 Lateral-Mode Discrimination and Modal Gain.- 3.3 Single-Frequency Operation.- 3.3.1 Number of Modes in Diode-Laser Arrays.- 3.3.2 Spontaneous-Emission Factor.- 3.3.3 Longitudinal Mode Structure.- 3.3.4 Spectral Linewidth.- 3.4 Frequency-Locking of Diode-Laser Oscillators.- 3.4.1 Frequency Locking of Independent Laser Oscillators.- 3.4.2 Influence of Nonuniformities on Frequency Locking.- 4. Theoretical Models for Monolithic Diode-Laser Arrays.- 4.1 Multi-Layer Waveguide Structures.- 4.2 Analysis of Diode-Laser Waveguide Structures.- 4.2.1 Effective-Index Method.- 4.2.2 Coupled-Mode Approximation.- 4.2.3 Bloch-Function Analysis of Laser Arrays.- 4.2.4 Two-Dimensional Waveguide Model of Laser Arrays.- 4.3 Self-Consistent Models.- 4.3.1 Electric-Field Propagation Model.- 4.3.2 Carrier-Transport Model.- 4.3.3 Thermal Model.- 4.3.4 Outline of Self-Consistent Numerical Procedure.- 4.3.5 Instability of Spatial Modes.- 4.4 Optical Coherence Theory.- 4.4.1 Mutual Coherence.- 4.4.2 Cross-Power Spectrum.- 4.4.3 Propagation of the Cross-Power Spectrum.- 4.4.4 Far-Field Mutual Coherence.- 4.4.5 Cross-Spectral Purity.- 5. Gain-Guided Diode-Laser Oscillators.- 5.1 Multiple-Stripe Gain-Guided Laser Array Structures.- 5.2 Gain-Tailored Structures.- 5.3 Unstable-Resonator Diode Lasers.- 5.3.1 Geometric Optics Analysis of Unstable Resonators.- 5.3.2 Unstable-Resonator Diode Lasers with Self-Collimated Output Beams.- 5.3.3 Half-Symmetric Unstable-Resonator Diode Lasers.- 5.3.4 Tapered-Cavity Diode Lasers.- 6. Index-Guided Diode-Laser Array Oscillators.- 6.1 Channeled-Substrate Planar Laser Arrays.- 6.2 Ridge-Guided Laser Arrays.- 6.3 Leaky-Wave-Coupled Arrays.- 6.3.1 Resonant Optical-Wave Coupling Model.- 6.3.2 Transverse and Lateral Structures of Antiguided Arrays.- 6.3.3 Basic Modal Characteristics of Antiguided Laser Arrays.- 6.3.4 Rigorous Modeling of Structural Tolerances for Antiguided Laser Arrays.- 6.3.5 Above-Threshold Mode Stability of an Antiguided Array.- 7. Surface-Emitting Diode-Laser Arrays.- 7.1 Fundamentals of GSE Diode-Laser Arrays.- 7.1.1 Grating Feedback and Output-Coupling Elements.- 7.1.2 Principles of GSE Laser Array Design and Operation.- 7.2 Mode Discrimination Properties of GSE Laser Arrays.- 7.2.1 Boundary-Element Model of Grating-Coupled Waveguides.- 7.2.2 Coupled-Wave Model of GSE Laser Arrays.- 7.2.3 Network Models of GSE Laser Arrays.- 7.2.4 Network Analysis of Ring-Configured GSE Laser Array.- 7.3 Vertical-Cavity Surface-Emitting Laser Arrays.- 7.3.1 Scaling of Two-Dimensional VCSEL Arrays.- 7.3.2 Modal Properties of Two-Dimensional VCSEL Arrays.- 8. Master-Oscillator Power-Amplifier Diode Lasers.- 8.1 Edge-Emitting MOPAs.- 8.1.1 Semiconductor-Diode Amplifier Arrays.- 8.1.2 Discrete Broad-Area MOPAs.- 8.1.3 Monolithic Edge-Emitting MOPAs.- 8.1.4 Tapered MOPAs.- 8.2 Grating-Coupled Surface-Emitting MOPAs.- 8.2.1 Cascaded Grating-Coupled Surface-Emitting MOPAs.- 8.2.2 Active Grating-Coupled MOPAs: Operating Principles.- 8.2.3 Active Grating-Coupled MOPAs: Performance Characteristics.- References.