High Power Diode Lasers

Abstract

1Motivation and introduction 2High power diode laser technlogy and characteristics 2.1Principles of diode operation 2.2Manufacturing technology 2.3Chip characterization methods and operation 2.4Broad area emitters and arrays 2.5High brightness emitters and arrays 3Packaging of diode laser bars 3.1General aspects 3.2Mounting of diode laser bars 3.3Cooling 3.3.1Introduction 3.3.2 Conduction cooling 3.3.3Micro-channel heatsinks 3.3.4Heatspreaders 3.4Expansion-matched packages 3.5Mounting of micro-optics 4Stacking and incoherent superposition 4.1 Introduction and Survey 4.2 Beam collimation 4.3 Techniques for Beam Combination 4.4 Stacking Techniques 4.5 Beam symmetrization and fiber coupling 4.6 Beam-Quality limits and comparison to coherent coupling 5 Laser systems: beam characteristics, metrology and standards 5.1 Introdiuction 5.2 Theoretical background of beam propagation 5.2.1 Preliminaries 5.2.2 Temporal integration, coherence 5.2.3 Wigner distribution 5.2.4 Propagation of the Wigner distribution through linear optical systems 5.3 Density distribution 5.3.1 Power density distribution in the far field 5.3.2 Width of a power density distribution in a transverse plane 5.4 Propagation of the beam width 5.4.1 Theoretical background 5.4.2 Beam classification 5.4.3 Propagation of the beam width of stigmatic and simple astigmatic beams 5.5. Measurement of the beam power 5.6 Measurement of the power density distribution and the beam propagation ratio, M^2 5.6.1 Camera systems 5.6.2 Mechanical scanning devices 5.6.3 Measuring beam caustics 5.6.4 Power density in the far field measurement 5.6.5 Evaluating the widths of ameasured power density distribution 5.6.6 Determination of the beam propagation ration, M^2 5.7 Beam positional stability 5.8 Wavefront of a laser 5.9 Lifetime 5.10 Table of international standards related to laser metrology 5.11 References 6 Diode laser systems 6.1 Introduction 6.2 Multi purpose laser systems 6.2.1 Optical cutting plotter with 100 W 6.2.2 Free space propagation systems in the kW range 6.2.3 Fibre coupled system in the kW range 6.2.4 High brightness system with 100 W 6.2.5 High brightness kW system 6.3 Modular diode laser systems 6.3.1 Soldering laser, integrated into a gripping tool - pick and join 6.3.2 Individually addressable intensity line 6.3.3 Line modules for contour adapted plastics welding 6.3.4 Diode laser line cutter 6.3.5 Annular diode laser tool 6.3.6 Process controlling modular diode laser system for transformation hardening 6.3.7 Ring shaped laser for laser assisted machining 6.4 List of symbols 6.5 References 7 Applications 7.1 Joining technologies 7.1.1 Introduction 7.1.2 Metal welding 7.1.3 Brazing 7.1.4 Soldering 7.1.5 Laser Beam Welding of Thermoplastics 7.1.6 References 7.2 Cutting and laser assisted machining technologies 7.2.1 Introduction 7.2.2 Precision cutting with the optical cutting plotter 7.2.3 Single-shot cutting-to-length 7.2.4 Oxygen cutting with annular beam 7.2.5 Laser asisted machining 7.3 Surface treatment 7.3.1 Introduction 7.3.2 Hardening 7.3.2.1 Process principles and equipment 7.3.2.1.1 Differences between / principles of hardening and remelting 7.3.2.1.2 Absorption depending on angle of incidence, material, surface roughness,