High-Power Diode Lasers

Roland Diehl (Ed.)
High-Power Diode Lasers
Fundamentals, Technology, Applications
With Contributions by Numerous Experts
With 260 Figures and 20 Tables
iNSTITUT FOR ANGEWANDTE PHYSlK
TECHN1SCHE UNIVERSITAT DARMSTADT
Springer
Contents
Introduction to Power Diode Lasers
Peter Unger
1. Fundamental Aspects of Diode Lasers
1.1. Emission and Absorption in Semiconductors
1.2. Basic Elements of Semiconductor Diode Lasers
1.3. Optical Gain and Threshold Condition
1.4. Edge- and Surface-Emitting Lasers
1.5. Lateral Confinement
1.6. Quantum-Well Structures
2. Fabrication Technology
._
3. Optical Waveguides and Resonators
3.1. Effective Refractive Index
3.2. Normalized Propagation Diagrams
3.3. Optical Near- and Far-Field Patterns
3.4. Fabry-Perot Resonator
3.5. Diode Laser Spectrum
3.6. Mirror Coatings
4. Rate Equations and High-Power Operation
4.1. Rate Equations for Electronic Carriers and Photons
4.2. Electrical and Optical Characteristics of Power Diode Lasers . . . .
4.3. Design Considerations for High-Power Operation
List of Symbols
List of Constants
Abbreviations for Indices
References
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X
Contents
Dynamics of High-Power Diode Lasers
Edeltraud Gehrig and Ortwin Hess
55
1. Microscopic Spatio-Temporal Properties of Diode Lasers
1.1. Role of Microscopic Spatio-Temporal Properties
in Macroscopic Laser Characteristics
1.2. Optical-Field Dynamics
1.3. Physics of the Active Semiconductor Medium
2. Spatio-Temporal Dynamics of High-Power Diode Lasers
2.1. Optical Injection
2.2. Influence of Laser Geometry and Facet Reflectivities
2.3. Dynamics of Optical Emission Characteristics
2.4. Spatial and Spectral Carrier Dynamics
2.5. Spatial and Spectral Refractive-Index and Gain Dynamics
3. Conclusion
List of Symbols
References
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Epitaxy of High-Power Diode-Laser Structures
Markus Weyers, Arnab Bhattacharya, Frank Bugge and Arne Knauer ... 83
1. Growth Methods
1.1. Molecular-Beam Epitaxy and Its Variants
1.2. Metalorganic Vapor-Phase Epitaxy
1.3. Comparison of MBE and MOVPE
2. Materials for High-Power Diode Lasers
2.1. GaAs and AlGaAs
2.2. GalnP and AlGalnP
2.3. GalnAsP on GaAs
2.4. InP. GalnAs(P) and AlGalnAs
3. Doping
3.1. N-Type Doping
3.2. P-Type Doping
4. Heterostructures
5. Strained Quantum Wells
5.1. Pseudomorphic Growth and Strain Relaxation
5.2. Strain Compensation
6. Device Results
List of Acronyms
References
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Contents
XI
GaAs Substrates for High-Power Diode Lasers
Georg Miiller, Patrick Berwian. Eberhard Buhrig
and Berndt Weinert
1. Selection of the Growth Method
1.1. Important Features of GaAs Crystal-Growth Methods
1.2. Liquid-Encapsulated Czochralski (LEC)
and Vapor-Controlled Czochralski (VCZ) Techniques
1.3. Thermal Stress and Dislocation Density
1.4. Methods of Directional Solidification:
Gradient Freeze and Bridgman Variants
2. Physico-Chemical Features of the VGF Technology
for the Growth of Si-Doped Low-EPD GaAs Single Crystals
2.1. Discussion of VGF Variants
2.2. Important Chemical Reactions in the VGF Growth
of Si-Doped GaAs
2.3. VGF Furnace Concepts
2.4. Preparation of Starting Materials and Procedure
of VGF Growth
3. Numerical Modeling for VGF-Process Optimization
3.1. Principles and Strategy of the Numerical Modeling
3.2. Optimization of VGF-Growth Equipment
3.3. Optimization of Growth Runs by Inverse Modeling
4. Crystal and Wafer Properties
4.1. Watering
4.2. Electrical Characterization and Silicon Doping
4.3. Optical Characterization by Infrared
and Photoluminescence Mapping
4.4. Residual Dislocations
r
5. Conclusion
List of Symbols
List of Acronyms
References
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High-Power Broad-Area Diode Lasers and Laser Bars
Gotz Erbert, Arthur BarwolfL Jiirgen Sebastian and Jens Tomm
173
1. Epitaxial Waveguide Structures for High-Power Diode Lasers
l.-l.-The Large Optical Cavity (LOC) Concept
2. Technology for Broad-Area Diode Lasers and Laser Bars
2.1. Processing of Contact Windows
2.2. Processing of Mesa Structures
2.3. Metallization
2.4. Laser-Bar Preparation
2.5. Facet Coating
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XII
Contents
3. Behavior of High-Power CW Diode Lasers
3.1. Influence of Heat on Laser Performance
3.2. Simulation of Temperature Distribution
3.3. Recent Results
List of Symbols
References
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199
201
213
216
218
Properties and Frequency Conversion
of High-Brightness Diode-Laser Systems
Klaus-Jochen Boiler, Bernard Beier and Richard Wallenstein
225
1. Beam Quality
1.1. The Diffraction Parameter M2
1.2. Measurement of the Wavefront
2. Single-Stripe Diode Lasers
3. High-Power Diode Lasers
4. Diode Amplifiers
5. AlGaAs Diode-MOPA Systems
6. Diode-MOPA Systems Based on InGaAs
7. Nonlinear Frequency Conversion
with High-Brightness Diode-MOPA Systems
7.1. Second-Harmonic Generation
7.2. Diode-Pumped Optical Parametric Oscillators
8. Summary
List of Symbols and Abbreviations
References
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239
241
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249
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256
257
259
Tapered High-Power, High-Brightness Diode Lasers:
Design and Performance
Michael Mikulla
265
1. Introduction
2. Theoretical Background
3. BPM Simulations
4. Epitaxial Layer Structures ...:
4.1. Comparison of LMG and LOC Structures
5. Broad-Area Diode Lasers with LMG Layer Structures
6. Fabrication of Tapered Devices
7. Experimental Results
7.1. Tapered Laser Oscillators
7.2. Tapered Laser Amplifiers
7.3. Tunable High-Brightness Diode-Laser Systems
7.4. Tapered Diode-Laser Arrays
8. Manufacturability
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284
Contents
9. Conclusion
List of Symbols
References
XIII
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287
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Cooling and Packaging of High-Power Diode Lasers
Peter Loosen
289
1. Basic Properties of Micro-Channel Coolers
for High-Power Diode Lasers
291
2. Manufacturing and Flow Dynamics of Cu Micro-Channel Coolers ... 295
3. Packaging of Diode-Laser Bars
297
List of Symbols
300
References
301
High-Power Diode Lasers for Direct Applications
Uwe Brauch, Peter Loosen and Hans Opower
303
1. Introduction (Hans Opower)
303
2. Incoherent Beam Combining (Peter Loosen)
309
2.1. Properties of High-Power Diode Lasers for Direct Applications . 311
2.2. Beam Quality of Incoherently Combined Beams
313
2.3. Technical Devices
316
2.4. Beam Collimation
320
2.5. Aperture Filling and Stacking Accuracy
325
2.6. Applications
328
2.7. Discussion and Perspectives
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331
3. Coherent Beam Combining (Uwe Brauch)
331
3.1. Coherence Properties of Semiconductor Diode Lasers
334
3.2. Combining of Diffraction-Limited Beams
336
3.3. Phase Coupling and Beam Combining
of Single-Longitudinal-Mode Lasers
345
3.4. Prospects and Limitations of Coherent Beam Combining
360
List of Symbols
362
References
364
New Concepts for Diode-Pumped Solid-State Lasers
Andreas Tunnermann, Holger Zellmer, Wolfram Schone,
Adolf Giesen and Karsten Contag
369
1. Fundamental Concepts of Diode-Pumped Solid-State Lasers
1.1. Thermal Considerations
2. Fiber Lasers
2.1. Laser-Active Waveguides
2.2. Double-Clad Fiber Lasers
2.3. Pump-Radiation Absorption in Double-Clad Fibers
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XIV
Contents
2.4. High-Power Laser Operation
2.5. Fiber-Laser Emission in the Visible Spectral Region
3. Thin-Disk Laser
3.1. Design Considerations
3.2. Numerical Simulation of the Thin-Disk Laser
3.3. Results and Discussion
3.4. Conclusion
List of Symbols
References
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Index
409