Femtosecond Laser Filamentation

1. Auflage 2010
ISBN: 978-1-4419-0688-5
Verlag: Springer-Verlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 130 Seiten

This book attempts to give a discussion of the physics and current and potential applications of the self-focusing of an intense femtosecond laser pulse in a tra- parent medium. Although self-focusing is an old subject of nonlinear optics, the consequence of self-focusing of intense femtosecond laser pulses is totally new and unexpected. Thus, new phenomena are observed, such as long range lam- tation, intensity clamping, white light laser pulse, self-spatial ltering, self-group phase locking, self-pulse compression, clean nonlinear uorescence, and so on. Long range propagation at high intensity, which is seemingly against the law of diffraction, is probably one of the most exciting consequences of this new sub- eld of nonlinear optics. Because the intensity inside the lament core is high, new ways of doing nonlinear optics inside the lament become possible. We call this lamentation nonlinear optics. We shall describe the generation of pulses at other wavelengths in the visible and ultraviolet (UV) starting from the near infrared pump pulse at 800 nm through four-wave-mixing and third harmonic generation, all in gases. Remotely sensing uorescence from the fragments of chemical and biological agents in all forms, gaseous, aerosol or solid, inside the laments in air is demonstrated in the labo- tory. The results will be shown in the last part of the book. Through analyzing the uorescence of gas molecules inside the lament, an unexpected physical process pertaining to the interaction of synchrotron radiation with molecules is observed.

Autoren/Hrsg.

Inhaltsverzeichnis

1;Preface;7
2;Acknowledgement;9
3;Contents;10
4;1 Introduction;13
4.1;1.1 Mature Physics and New Development;13
4.2;1.2 Phase Effect of a Laser Pulse Propagating in an Optical Medium;15
4.3;1.3 Multiphoton and Tunnel Ionization;16
4.4;1.4 Optical Breakdown;18
4.5;1.5 Intense Femtosecond Laser Beam Attenuation;20
5;2 Filamentation Physics;22
5.1;2.1 Some Experimental Observations;22
5.2;2.2 Experimental Definition of a Filament by Burn Paper;26
5.3;2.3 Single Filamentation Physics;27
5.3.1;2.3.1 Slice-by-Slice Self-Focusing;27
5.3.2;2.3.2 Intensity Clamping;32
5.3.3;2.3.3 Is There Optical Breakdown During Filamentation?;34
5.3.4;2.3.4 Effect of External Focusing;36
5.3.5;2.3.5 Background Energy Reservoir;37
5.3.6;2.3.6 Self-Spatial Mode Filtering;42
5.3.7;2.3.7 Self-Phase Modulation, Self-Steepening and White Light Laser (Supercontinuum);43
5.3.8;2.3.8 Conical Emission;47
5.3.9;2.3.9 Ring Structure at the Pump Wavelength;49
5.3.10;2.3.10 Self-Pulse Compression;49
5.3.11;2.3.11 X-wave;51
5.4;2.4 Full Evolution of a Single Filament;51
5.5;2.5 Maturity of a Filament;57
5.6;2.6 Filamentation Without Ionization;57
5.7;2.7 What Is a Filament?;58
6;3 Theory of Single Filamentation;60
6.1;3.1 Introduction;60
6.2;3.2 Filamentation in Air;60
6.3;3.3 Numerical Solution of Filamentation in Air;62
6.4;3.4 Filamentation in Condensed Matter;66
6.5;3.5 x-Wave and Conical Emission1 ;66
7;4 Multiple Filamentation;71
7.1;4.1 Introduction;71
7.2;4.2 Multiple Filamentation: Experimental Observation;71
7.3;4.3 Interference and Competition of Multiple Filaments;74
7.4;4.4 Theory of Multiple Filamentation;77
7.5;4.5 The Challenge of Long Distance Filamentation;78
7.6;4.6 Long Distance Multiple Filamentation Control;78
8;5 Filamentation Nonlinear Optics: General;81
8.1;5.1 Self-Actions;81
8.2;5.2 Self-Remote Projection in Air;82
8.3;5.3 Self-Pulse Compression;83
8.4;5.4 Exploitations of the Self-Actions;84
9;6 Filamentation Nonlinear Optics: Third Harmonic Generation and Four-Wave-Mixing Inside a Filament;87
9.1;6.1 Introduction;87
9.2;6.2 Third Harmonic Generation Inside a Filament in Air (Theoretical Analysis);87
9.3;6.3 Experiment on THG in Air;93
9.4;6.4 Conical Emission and Superbroadening of the Third Harmonic in Air;95
9.5;6.5 Efficient Tunable Few Cycle Visible Pulse Generation Through Four-Wave-Mixing Inside the Filament Core;95
9.6;6.6 Self-Group-Phase Locking During Four-Wave-Mixing Inside a Filament;98
9.7;6.7 Derivation of Equation ( 6.1 );99
10;7 Remote Sensing Using Filamentation;102
10.1;7.1 Introduction;102
10.2;7.2 Remote Control of Filamentation;103
10.3;7.3 Physical Considerations;105
10.4;7.4 Detection of Chemical and Biological Agents in Air;106
10.4.1;7.4.1 Molecules in the Gas/Vapor Phase;106
10.4.2;7.4.2 Biological Targets;108
10.4.3;7.4.3 Metallic Targets;109
10.4.4;7.4.4 Water Aerosols Containing Metallic Salts;109
10.5;7.5 Conclusion and Looking Ahead;110
11;8 Challenges Ahead;111
11.1;8.1 Multiple Filamentation;112
11.1.1;8.1.1 Why Does a Large Diameter Beam Diverge Slowly Over Long Distances When There Is Multiple Filamentation?;112
11.1.2;8.1.2 Filament Collaboration;112
11.1.3;8.1.3 Optimum Wavelength to Produce the Broadest and Strongest White Light;113
11.1.4;8.1.4 Filament Control Using a Deformable Mirror;113
11.2;8.2 Time-Resolved Excitation of Superexcited States of Molecules;114
11.3;8.3 Ultrafast Birefringence;117
11.3.1;8.3.1 Filament-Induced Birefringence;118
11.3.2;8.3.2 Excitation of Molecular Rotational Wave Packets in Air and Polarization Separation;122
11.3.3;8.3.3 Just the Beginning of Filament-Induced Birefringence;126
12;References;127
13;Index;133