Thin Film Micro-Optics

Transcription

1 Thin Film Micro-Optics New Frontiers of Spatio-Temporal Beam Shaping Ruediger Grunwald Max Born Institut for Nonlinear Optics and Short Pulse Spectroscopy Berlin, Germany ELSEVIER Amsterdam Boston Heidelberg London New York Oxford Paris San Diego San Francisco Singapore Sydney Tokyo

2 Thin-film microoptics - New frontiers of spatio-temporal beam shaping TABLE OF CONTENTS PREFACE ACKNOWLEDGEMENTS LIST OF ABBREVIATIONS vii ix xvii 1. INTRODUCTION 1 2. MICRO-OPTICS The concept of microoptics Microoptics and macrooptics Scaling laws for a size reduction Diffraction and Fresnel number Types of microoptical components Refractive microoptics Specific properties of refractive microoptical components Gradient index lenses Spherical surface relief lenses Fresnel lenses Fabrication of refractive components Reflective microoptics Diffractive microoptics Hybrid microoptics Replication and structure transfer Specific properties of array structures Types and general features of microoptical array structures Fill factor, efficiency and symmetry Spatial frequencies and Fresnel numbers Cross-talk and self-imaging effects Wavefront detection with array components Gabor superlens Stacked and planar microoptics Problems and trends 35

3 Table of Contents THIN-FILM OPTICS The concept of thin-film optics Single transparent layer on substrates Uniform Fabry-Perot etalon at monochromatic illumination Fabry-Perot etalon of space-variant thickness at monochromatic illumination Fabry-Perot etalon of space-variant thickness at polychromatic illumination Transmission of ultrashort pulses through plane-parallel etalon structures Quarter-wave layers and half-wave layers at monochromatic illumination Admittance of absorbing layers at optical frequencies Dielectric multilayer structures The multilayer approach Method of characteristic matrices Dispersion management by layer stacks of adapted spectral phases Diffraction management by layer stacks of spatially variable reflectance Metal and metal-dielectric coatings Single reflecting metal layers Metal-dielectric layers as Gires-Tournois interferometer structures Problems and trends 57 THIN-FILM MICROOPTICS The concept of thin-film microoptics Techniques for the fabrication of structured thin films: from macroscopic to microscopic scale Subtractive and modifying techniques Uniformity and nonuniformity of deposited layers Separately rotating masks for structured light exposure and vapor deposition Fixed thick shadow masks and extended sputtering sources Fixed thin circular shadow masks rotating with the substrate Thick shadow masks fixed at the substrates in a rotating system with point source Deposition of arrays of microoptical components with miniaturized shadow masks Simulation of the deposition through thick shadow masks fixed on a substrate in a system with planetary rotation 67

4 Table of Contents xiii 4.3. Specific properties of thin-film microoptical components Specific advantages of thin-film deposition technique with shadow masks Specific advantages of thin-film microoptical design Thin-film microoptics on substrates: Specific properties and design constraints Contact angle and maximum angle of incidence of thin-film microlenses Types of thin-film microoptical components Fabrication of thin-film microoptics with shadow masks Vacuum deposition with planetary rotation and shadow masks Types of shadow masks for the deposition of thin-film microstructures Generation of arrays of high fill factors with the method of crossed deposition Wire-grid masks Deposition of nonspherical elements with slit and hole array masks of conical apertures Generation of arrays of high fill factors and parabolic profiles with mesh-shaped masks Pre-processing of polymer substrates for improving the adhesion of thin-film microoptics Multilayer and compound microoptics Multilayer microoptics Metal-dielectric structures Structure transfer of thin-film microoptical components by reactive ion etching Nanolayer microoptics VUV-capable transparent thin-film microoptics Problems and trends 109 CHARACTERIZATION OF THIN-FILM MICROOPTICS Specific measuring problems Interferometric characterization of thin-film microlens arrays Phase shift interferometer Characterization of shape distribution and periodicity of microlens arrays Optical functions of thin-film microlens arrays Reflectance mapping of multilayer microoptics Spatially resolved measurement of specular reflectance Spatial reflectance mapping with angular resolution Near field propagation measurements 123

5 xiv Table of Contents SPATIAL BEAM SHAPING WITH THIN-FILM MICROOPTICS Hybrid microoptics for improved efficiency of laser diode collimation Motivation and basic concepts Slow-axis collimation with compact systems of cylindrical microlenses Angular-adapted micro-gradient AR coatings Mode-selection in laser resonators Stability management of compact solid-state laser resonators with micro-mirrors Talbot resonators with micro-mirror arrays Mode stabilization in laser diode MOPA-systems with external resonator for second harmonic generation Generation of Bessel-like nondiffracting beams Nondiffracting beams Bessel-like beams Generation of arrays of microscopic Bessel-like beams with thin-film axicons Spatial self-reconstruction of Bessel-like beams Self-apodized truncation of Bessel beams as a first way to shape needle beams Ultrafiat thin-film axicons of extremely small conical angles as a second way to generate needle beams Shack-Hartmann wavefront sensing at extreme laser parameters with Bessel-like beams Particular features of Shack-Hartmann sensors with Bessel-like nondiffracting beams Transmissive and reflective setups with angular-tolerant thin-film microaxicons VUV laser beam array generation and multichannel materials processing VUV beam array generation with thin-film microoptics Beam cleaning by absorption VUV materials processing with thin-film microoptics 163 SPATIO-TEMPORAL BEAM SHAPING AND CHARACTERIZATION OF ULTRASHORT-PULSE LASERS Motivation Coherence mapping Microoptical approaches based on multichannel interferometry Coherence mapping with thin-film Fabry-Perot arrays Coherence mapping with arrays of Bessel-like beams 172

6 Table of Contents XV Decoding of axial coherence information with arrays of Bessel-like beams Coherence mapping with the Talbot effect Spatio-temporal autocorrelation Processing and characterization of ultrashort optical pulses Concept of the collinear matrix autocorrelator based on arrays of Bessel-like beams Transversal autocorrelation information in Bessel-like beams Wavefront autocorrelation experiments Hyperspectral sensing of polychromatic wavefronts Prospects for a spatially-resolved spectral phase measurement Hyperspectral Shack-Hartmann wavefront sensor with graxicon arrays Generation of optical spatio-temporal X-pulses with thin-film structures X-waves and X-pulses as spectral interference phenomena in spatio-temporal domain Generation and direct detection of arrayed microscopic-size pulsed optical Bessel-like X-waves and single macroscopic Bessel-Gauss X-pulses Self-apodized truncation of ultrashort and ultrabroadband Bessel pulses Spatial propagation of ultrashort-pulsed and ultrabroadband truncated Bessel-like beams generated with thin-film beam shapers Spatio-spectral and spatio-temporal transfer of ultrashortpulsed and ultrabroadband truncated Bessel-Gauss beams Comparison to ultrashort-pulsed Gaussian beams Spatio-temporal self-reconstruction and nondiffracting images Self-reconstruction and spatio-temporal information Nondiffracting images OUTLOOK 205 REFERENCES 207 FIGURE CREDITS 253 GLOSSARY 255 INDEX 279