Thin Film Micro-Optics (eBook)

Front Cover 1
Thin Film Micro-Optics 4
Copyright Page 5
TABLE OF CONTENTS 12
PREFACE 8
ACKNOWLEDGEMENTS 10
LIST OF ABBREVIATIONS 18
Chapter 1 INTRODUCTION 20
Chapter 2 MICRO-OPTICS 22
2.1. The concept of microoptics 22
2.2. Microoptics and macrooptics 25
2.2.1. Scaling laws for a size reduction 25
2.2.2. Diffraction and Fresnel number 26
2.3. Types of microoptical components 28
2.4. Refractive microoptics 30
2.4.1. Specific properties of refractive microoptical components 30
2.4.2. Gradient index lenses 31
2.4.3. Spherical surface relief lenses 32
2.4.4. Fresnel lenses 36
2.4.5. Fabrication of refractive components 37
2.5. Reflective microoptics 38
2.6. Diffractive microoptics 40
2.7. Hybrid microoptics 42
2.8. Replication and structure transfer 44
2.9. Specific properties of array structures 45
2.9.1. Types and general features of microoptical array structures 45
2.9.2. Fill factor, efficiency and symmetry 46
2.9.3. Spatial frequencies and Fresnel numbers 48
2.9.4. Cross-talk and self-imaging effects 49
2.9.5. Wavefront detection with array components 51
2.9.6. Gabor superlens 53
2.10. Stacked and planar microoptics 54
2.11. Problems and trends 54
Chapter 3 THIN-FILM OPTICS 58
3.1. The concept of thin-film optics 58
3.2. Single transparent layer on substrates 58
3.2.1. Uniform Fabry-Perot etalon at monochromatic illumination 59
3.2.2. Fabry-Perot etalon of space-variant thickness at monochromatic illumination 63
3.2.3. Fabry-Perot etalon of space-variant thickness at polychromatic illumination 64
3.2.4. Transmission of ultrashort pulses through plane-parallel etalon structures 66
3.2.5. Quarter-wave layers and half-wave layers at monochromatic illumination 67
3.2.6. Admittance of absorbing layers at optical frequencies 68
3.3. Dielectric multilayer structures 70
3.3.1. The multilayer approach 70
3.3.2. Method of characteristic matrices 70
3.3.3. Dispersion management by layer stacks of adapted spectral phases 72
3.3.4. Diffraction management by layer stacks of spatially variable reflectance 73
3.4. Metal and metal-dielectric coatings 75
3.4.1. Single reflecting metal layers 75
3.4.2. Metal-dielectric layers as Gires-Tournois interferometer structures 75
3.5. Problems and trends 76
Chapter 4 THIN-FILM MICROOPTICS 78
4.1. The concept of thin-film microoptics 78
4.2. Techniques for the fabrication of structured thin films: from macroscopic to microscopic scale 79
4.2.1. Subtractive and modifying techniques 79
4.2.2. Uniformity and nonuniformity of deposited layers 80
4.2.3. Separately rotating masks for structured light exposure and vapor deposition 81
4.2.4. Fixed thick shadow masks and extended sputtering sources 82
4.2.5. Fixed thin circular shadow masks rotating with the substrate 83
4.2.6. Thick shadow masks fixed at the substrates in a rotating system with point source 83
4.2.7. Deposition of arrays of microoptical components with miniaturized shadow masks 84
4.2.8. Simulation of the deposition through thick shadow masks fixed on a substrate in a system with planetary rotation 86
4.3. Specific properties of thin-film microoptical components 90
4.3.1. Specific advantages of thin-film deposition technique with shadow masks 90
4.3.2. Specific advantages of thin-film microoptical design 90
4.3.3. Thin-film microoptics on substrates: Specific properties and design constraints 92
4.3.4. Contact angle and maximum angle of incidence of thin-film microlenses 97
4.4. Types of thin-film microoptical components 97
4.5. Fabrication of thin-film microoptics with shadow masks 99
4.5.1. Vacuum deposition with planetary rotation and shadow masks 99
4.5.2. Types of shadow masks for the deposition of thin-film microstructures 100
4.5.3. Generation of arrays of high fill factors with the method of crossed deposition 102
4.5.4. Wire-grid masks 104
4.5.5. Deposition of nonspherical elements with slit and hole array masks of conical apertures 107
4.5.6. Generation of arrays of high fill factors and parabolic profiles with mesh-shaped masks 112
4.6. Pre-processing of polymer substrates for improving the adhesion of thin-film microoptics 114
4.7. Multilayer and compound microoptics 117
4.7.1. Multilayer microoptics 117
4.7.2. Metal-dielectric structures 118
4.8. Structure transfer of thin-film microoptical components by reactive ion etching 122
4.9. Nanolayer microoptics 124
4.10. VUV-capable transparent thin-film microoptics 126
4.11. Problems and trends 128
Chapter 5 CHARACTERIZATION OF THIN-FILM MICROOPTICS 130
5.1. Specific measuring problems 130
5.2. Interferometric characterization of thin-film microlens arrays 131
5.2.1. Phase shift interferometer 131
5.2.2. Characterization of shape distribution and periodicity of microlens arrays 132
5.2.3. Optical functions of thin-film microlens arrays 135
5.3. Reflectance mapping of multilayer microoptics 138
5.3.1. Spatially resolved measurement of specular reflectance 138
5.3.2. Spatial reflectance mapping with angular resolution 142
5.4. Near field propagation measurements 142
Chapter 6 SPATIAL BEAM SHAPING WITH THIN-FILM MICROOPTICS 144
6.1. Hybrid microoptics for improved efficiency of laser diode collimation 144
6.1.1. Motivation and basic concepts 144
6.1.2. Slow-axis collimation with compact systems of cylindrical microlenses 147
6.1.3. Angular-adapted micro-gradient AR coatings 149
6.2. Mode-selection in laser resonators 152
6.2.1. Stability management of compact solid-state laser resonators with micro-mirrors 152
6.2.2. Talbot resonators with micro-mirror arrays 153
6.2.3. Mode stabilization in laser diode MOPA-systems with external resonator for second harmonic generation 156
6.3. Generation of Bessel-like nondiffracting beams 158
6.3.1. Nondiffracting beams 158
6.3.2. Bessel-like beams 160
6.3.3. Generation of arrays of microscopic Bessel-like beams with thin-film axicons 162
6.3.4. Spatial self-reconstruction of Bessel-like beams 165
6.3.5. Self-apodized truncation of Bessel beams as a first way to shape needle beams 166
6.3.6. Ultraflat thin-film axicons of extremely small conical angles as a second way to generate needle beams 171
6.4. Shack-Hartmann wavefront sensing at extreme laser parameters with Bessel-like beams 174
6.4.1. Particular features of Shack-Hartmann sensors with Bessel-like nondiffracting beams 174
6.4.2. Transmissive and reflective setups with angular-tolerant thin-film microaxicons 176
6.5. VUV laser beam array generation and multichannel materials processing 179
6.5.1. VUV beam array generation with thin-film microoptics 179
6.5.2. Beam cleaning by absorption 181
6.5.3. VUV materials processing with thin-film microoptics 182
Chapter 7 SPATIO-TEMPORAL BEAM SHAPING AND CHARACTERIZATION OF ULTRASHORT-PULSE LASERS 186
7.1. Motivation 186
7.2. Coherence mapping 187
7.2.1. Microoptical approaches based on multichannel interferometry 187
7.2.2. Coherence mapping with thin-film Fabry-Perot arrays 190
7.2.3. Coherence mapping with arrays of Bessel-like beams 191
7.2.4. Decoding of axial coherence information with arrays of Bessel-like beams 195
7.2.5. Coherence mapping with the Talbot effect 195
7.3. Spatio-temporal autocorrelation 198
7.3.1. Processing and characterization of ultrashort optical pulses 198
7.3.2. Concept of the collinear matrix autocorrelator based on arrays of Bessel-like beams 199
7.3.3. Transversal autocorrelation information in Bessel-like beams 201
7.3.4. Wavefront autocorrelation experiments 202
7.4. Hyperspectral sensing of polychromatic wavefronts 207
7.4.1. Prospects for a spatially-resolved spectral phase measurement 207
7.4.2. Hyperspectral Shack-Hartmann wavefront sensor with graxicon arrays 209
7.5. Generation of optical spatio-temporal X-pulses with thin-film structures 212
7.5.1. X-waves and X-pulses as spectral interference phenomena in spatio-temporal domain 212
7.5.2. Generation and direct detection of arrayed microscopic-size pulsed optical Bessel-like X-waves and single macroscopic Bessel-Gauss X-pulses 213
7.6. Self-apodized truncation of ultrashort and ultrabroadband Bessel pulses 215
7.6.1. Spatial propagation of ultrashort-pulsed and ultrabroadband truncated Bessel-like beams generated with thin-film beam shapers 216
7.6.2. Spatio-spectral and spatio-temporal transfer of ultrashort-pulsed and ultrabroadband truncated Bessel-Gauss beams 218
7.6.3. Comparison to ultrashort-pulsed Gaussian beams 220
7.7. Spatio-temporal self-reconstruction and nondiffracting images 221
7.7.1. Self-reconstruction and spatio-temporal information 221
7.7.2. Nondiffracting images 222
Chapter 8 OUTLOOK 224
REFERENCES 226
FIGURE CREDITS 272
GLOSSARY 274
INDEX 298