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Femtosecond Laser Filamentation

:	See Leang Chin
:	Femtosecond Laser Filamentation
:	Springer-Verlag
:	9781441906885
:	1
:	CHF 85.30
:

:	Theoretische Physik
:	English

:	130
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

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.

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