Ultrafast Laser Technologies and Applications, livre ebook

This book gathers original tutorials delivered as lectures by the authors at the international Femto-UP 2020 School, which took place online from 8th to 29th of March 2021 and gathered 600participants worldwide. Like the previous occurrences of the Femto-UP School, the 2020 edition and this Book do target a multidisciplinary public of scientists at various points of their carrier from undergraduate and graduate students to senior researchers and technical staff. The aim is to provide generic scientific knowledge on ultrafast laser technologies including generation, amplification, manipulation and characterization of ultrashort laser pulses, and pedagogical accounts of a selection of state-of-the-art applications of ultrashort laser pulses.

The Femto-UP 2020 School comprised numerical practical sessions using original pedagogical or technical numerical tools (based on the Python programming language) also included to this book as supplementary electronic material.

Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . III

Authors List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . VII

CHAPTER 1

Around the Genesis of Femto-Lasers . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 1

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 16

CHAPTER 2

Generation of Femtosecond Pulses . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 19

2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 19

2.2 Description of Ultrashort Light Pulses. . . . . . . . . . . . . . . . . . . .. . . . . 19

2.2.1 Real and Complex Electric Fields . . . . . . . . . . . . . . . . . . . .. . . 19

2.2.2 Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 21

2.2.3 Temporal and Spectral Widths . . . . . . . . . . . . . . . . . . . .. . . . . 22

2.2.4 Case of a Gaussian Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 22

2.2.5 Spectral Phase . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 23

2.2.6 Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 25

2.3 Generation of Femtosecond Pulses. . . . . . . . . . . . . . . . . . . .. . . . . . . . 26

2.3.1 Fundamental of Mode-Locking . . . . . . . . . . . . . . . . . . . .. . . . . 26

2.3.2 Group Velocity Dispersion Management . . . . . . . . . . . . . . . . . . 29

2.3.3 Oscillator Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 32

2.4 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 34

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 35

CHAPTER 3

Trends, Challenges and Applications of High-Average Power Ultrafast Lasers. . . . . . .. . 37

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 37

3.2 Summary of Important Ultrashort Pulse Parameters . . . . . . . . . . . . . . 38

3.3 High Average Power Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 41

3.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 41

3.3.2 Example: The Thin-Disk Geometry . . . . . . . . . . . . . . . . . . . .. 42

3.3.3 State of the Art of the Technology . . . . . . . . . . . . . . . . . . . .. . 45

3.3.4 Applications Driving These Advances . . . . . . . . . . . . . . . . . . . . 46

3.4 Ongoing Challenge for High-Power Ultrafast Laser Technology: Pulse Duration. . .. . .. . . . .. . . . . . 47

3.4.1 Self-Phase Modulation and Self-Focusing . . . . . . . . . . . . . . . . . 48

3.4.2 State-of-the-Art Pulse Compression of High-Average Power UltrafastLasers . . . . .. . . . .. . . . . . . . . 52

3.5 Conclusion and Outlook Towards Future Directions . . . . . . . . . . . . . . 54

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 54

CHAPTER 4

Basics of Femtosecond Pulse Manipulation: Simple Numerical Tools . . . . . . . 57

4.1 Presentation of Useful Functions . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 58

4.1.1 Travelling Between Time and Frequency . . . . . . . . . . . . . . . . . 59

4.1.2 Fourier Transform and Inverse Fourier Transform . . . . . . . . . . . 60

4.1.3 Definition of Electric Fields . . . . . . . . . . . . . . . . . . . .. . . . . . . 62

4.1.4 Pulse Duration . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 65

4.1.5 Time–FrequencyRepresentations . . . . . . . . . . . . . . . . . . . . . . . 66

4.2 Influence of the Spectral Phase . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 70

4.2.1 Effect of a Linear Spectral Phase . . . . . . . . . . . . . . . . . . . .. . . 71

4.2.2 Quadratic Spectral Phase . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 72

4.2.3 Cubic Spectral Phase . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 75

4.3 Linear Dispersion in Different Media . . . . . . . . . . . . . . . . . . . .. . . . . . 77

4.3.1 Refractive Index . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 78

4.3.2 Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 78

4.3.3 Definition of Input Pulse . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 79

4.3.4 Propagation in Air . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 80

4.3.5 Propagation in SiO2 . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 84

4.3.6 Temporal Broadening vs. Duration of the Input Pulse . . . . . . . 84

4.3.7 Compensation of Dispersion . . . . . . . . . . . . . . . . . . . .. . . . . . . 86

4.4 Self-Phase Modulation (SPM) . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 88

4.4.1 Influence of Self-Phase Modulation on a Gaussian Pulse . . . . . . 89

4.4.2 When Does Self-Phase Modulation Become a Problem? . . . . . . 92

4.4.3 Compensation of Self-Phase Modulation by a Quadratic Phase . 93

4.4.4 Post-Compression of Femtosecond Laser Pulses . . . . . . . . . . . . 96

4.5 Influence of Mirrors on Polarization . . . . . . . . . . . . . . . . . . . .. . . . . . 100

4.5.1 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 100

4.5.2 Reflectivity in Amplitude in S and P . . . . . . . . . . . . . . . . . . . . 101

4.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 107

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 108

CHAPTER 5

Femtosecond Pulse Shaping and Characterization: From Simulation to ExperimentalPulse Retrieval Using a Python-Based User Friendly Interface..111

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 111

5.2 Simulation and Retrieval of Synthetic Laser Pulses . . . . . . . . . . . . . . . 113

5.2.1 Pulse Shaping and Field Representation . . . . . . . . . . . . . . . . . . 113

5.2.2 Simulation Module . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 114

5.2.3 Retrieving Traces . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 117

5.3 Implementation in the Laboratory and Retrieval of Experimental Data . .. . . . . . . . . . 118

5.3.1 Experimental Pulse Retrieval: The Example of Post-Compression in aHollow-Core Fiber.. . . . 118

5.3.2 Interfacing a Dispersion Scan Measurement in PyMoDAQ . . . . 120

5.3.3 Retrieving the Temporal Profile of Few-Cycle Pulses Using PyMoDAQ-Femto. . . .. . . . . .. . . . . 121

5.3.4 Examples of Retrieved Pulses . . . . . . . . . . . . . . . . . . . .. . . . . . 125

5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 127

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 127

CHAPTER 6

High-Order Harmonic Generation (HHG): From Concept to Applications . . . 129

6.1 Basic Characteristics of a HHG Source and Historical Context . . . . . . 130

6.2 Semi-Classical Model for HHG: From Three-Step Model to SFA byLewenstein . . . .. . . . . .. . . . 133

6.3 Macroscopic Study of HHG: The Problem of Phase-Matching andRe-Absorption Limit . . .. . . . . . . . . 138

6.4 The Attosecond Structure of HHG . . . . . . . . . . . . . . . . . . . .. . . . . . . 147

6.5 New Trends in HHG . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 153

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 154

Bonus: The Lewenstein Model for Dummies . . . . . . . . . . . . . . . . . . . .. . . . . 156

CHAPTER 7

Ultra-Intense Laser Pulses and the High Power Laser System at Extreme LightInfrastructure – Nuclear Physics . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 165

7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 166

7.2 From Fundamental Forces to the Technology for Producing the HighestIntensities. . . .. . . . . 166

7.2.1 Laser Beam and Laser Pulse . . . . . . . . . . . . . . . . . . . .. . . . . . 166

7.2.2 Why Does Intensity Matter? . . . . . . . . . . . . . . . . . . . .. . . . . . 171

7.2.3 Temporal Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 174

7.2.4 Chirped Pulse Amplification (CPA) Architecture . . . . . . . . . . . 175

7.3 The ELI-NP HPLS Laser System . . . . . . . . . . . . . . . . . . . .. . . . . . . . 176

7.3.1 The HPLS Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 176

7.3.2 HPLS Compliance with Specifications . . . . . . . . . . . . . . . . . . . 180

7.3.3 Beam Transport to the Experimental Areas . . . . . . . . . . . . . . . 182

7.4 Extreme Light Infrastructure . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 183

7.4.1 ELI-Beamlines . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 184

7.4.2 ELI-ALPS . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 184

7.4.3 ELI-NP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 186

7.4.4 ELI Status . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 186

7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 187

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 187

CHAPTER 8

Coherent Multidimensional Spectroscopies: Advanced Spectroscopic Techniquesto Unveil Complex Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 191

8.2 Electronic Transitions in 2DES Spectra . . . . . . . . . . . . . . . . . . . .. . . . 194

8.2.1 How a 2DES Map is Built . . . . . . . . . . . . . . . . . . . . . . . . . . .. 194

8.2.2 Third-Order Signal in a 2DES Map . . . . . . . . . . . . . . . . . . . .. 196

8.2.3 Diagonal and Off-Diagonal Signals . . . . . . . . . . . . . . . . . . . .. . 198

8.2.4 Signal as a Function of t2: Population and Coherence Decay . . . 200

8.3 Experimental Considerations and Implementations . . . . . . . . . . . . . . . 202

8.4 Application to Complex Dynamics . . . . . . . . . . . . . . . . . . . .. . . . . . . 203

8.4.1 Biological Light Harvesting and Photosynthesis . . . . . . . . . . . . 204

8.4.2 Artificial Molecular Nano-Systems . . . . . . . . . . . . . . . . . . . .. . 204

8.4.3 Colloidal Semiconductor Nanocrystals (Quantum Dots) . . . . . . 206

8.4.4 Solid-State Materials Based on Semiconductor Nanocrystals . . . 208

8.4.5 Operating Devices and Chemical Reactions . . . . . . . . . . . . . . . 208

8.5 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 209

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 210

CHAPTER 9

Nonlinear Optical Imaging at the Nanoscale . . . . . . . . . . . . . . . . . . . .. . . . . 221

9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 221

9.2 Principles of Nonlinear Optical Microscopy . . . . . . . . . . . . . . . . . . . .. 224

9.2.1 One- and Two-Photon Fluorescence Microscopy . . . . . . . . . . . . 224

9.2.2 Second-Order Coherent Nonlinear Microscopy . . . . . . . . . . . . . 229

9.2.3 Practical Aspects of Nonlinear Microscopy . . . . . . . . . . . . . . . . 231

9.2.4 Third-Harmonic Generation and Four-Wave Mixing . . . . . . . . . 235

9.2.5 Coherent Anti-Stokes Raman Scattering and Stimulated RamanScattering . . . . .. . . . .. . . . . . . . . 236

9.3 Polarized Nonlinear Microscopy . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 236

9.3.1 Molecular Order . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 237

9.3.2 Polarized Two-Photon Fluorescence Microscopy . . . . . . . . . . . . 238

9.3.3 Polarized Second Harmonic Generation . . . . . . . . . . . . . . . . . . 241

9.3.4 Polarized FWM and CARS . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

9.3.5 Sub-Diffraction Vectorial Imaging in Metal Nanostructures. . . . 245

9.4 In Depth Nonlinear Microscopy in Complex Media . . . . . . . . . . . . . . . 247

9.4.1 Nonlinear Microscopy in the Presence of Aberrations: AdaptiveOptics . . . . . . . . . ... . . . . . . . . . . . . . 247

9.4.2 Nonlinear Microscopy in Scattering Media . . . . . . . . . . . . . . . . 247

9.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 252

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 252