Ultrashort Pulse Laser Technology: Laser Sources and Applications

365 Pages·2015·17.14 MB·English

by  S. Nolte

Springer Series in Optical Sciences 195
Stefan Nolte
Frank Schrempel
Friedrich Dausinger E ditors
Ultrashort
Pulse Laser
Technology
Laser Sources and Applications
Springer Series in Optical Sciences
Volume 195
Founded by
H.K.V. Lotsch
Editor-in-Chief
William T. Rhodes, Georgia Institute of Technology, Atlanta, USA
Editorial Board
Ali Adibi, Georgia Institute of Technology, Atlanta, USA
Theodor W. Hänsch, Max-Planck-Institut für Quantenoptik, Garching, Germany
Ferenc Krausz, Ludwig-Maximilians-Universität München, Garching, Germany
Barry R. Masters, Cambridge, USA
Katsumi Midorikawa, Saitama, Japan
Herbert Venghaus, Fraunhofer Institut für Nachrichtentechnik, Berlin, Germany
Horst Weber, Technische Universität Berlin, Berlin, Germany
Harald Weinfurter, Ludwig-Maximilians-Universität München, München,
Germany
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Stefan Nolte Frank Schrempel
(cid:129)
Friedrich Dausinger
Editors
Ultrashort Pulse Laser
Technology
Laser Sources and Applications
123
Editors
StefanNolte Friedrich Dausinger
Institute of Applied Physics Dausinger +Giesen GmbH
Friedrich-Schiller-University Jena Stuttgart
Jena Germany
Germany
FrankSchrempel
Institute of Applied Physics
Friedrich-Schiller-University Jena
Jena
Germany
ISSN 0342-4111 ISSN 1556-1534 (electronic)
SpringerSeries inOptical Sciences
ISBN978-3-319-17658-1 ISBN978-3-319-17659-8 (eBook)
DOI 10.1007/978-3-319-17659-8
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Preface
Today, ultrafast lasers providing pulses with a duration of a several femtoseconds
(1fs=10−15s)uptoafewpicoseconds(1ps=10−12s)arecommerciallyavailable
and are gaining more and more attention in the area of precise microstructuring.
This is due to the fact that they enable completely new machining approaches
impossible by applying conventional tools. The short interaction times result in
strong non-equilibrium processes. Consequently, thermal and mechanical damage
canbeminimizedandprocessingwithpracticallynomelteveninmetalprocessing
becomes possible resulting in sub-µm precision. The high intensities achievable
when focusing ultrashort laser pulses even of moderate pulse energies allow for
nonlinear interaction processes, which are the basis for processing transparent
materials. Application examples are, e.g. the cutting offragile glass structures for
displays, the structuring of thin-films in photovoltaics to increase the solar cell
efficiency, and the fabrication of LEDs or computer chips. Fantastic opportunities
open up in the field of medicine. Here, for example highly precise cuts with
minimaldamageinsidethehumaneyeenableabsolutelynewtherapyopportunities
for cataract or presbyopia treatment. Thus, ultrashort laser pulse systems are uni-
versal tools with a plethora of applications in precise micro-manufacturing and
medicine.
However, all these opportunities come along with a multitude of various chal-
lenges. On theone hand the system technology is rather complex and on theother
hand the nonlinear effects during beam propagation and during the interaction
processrequirefundamentalunderstandingandprecisecontrol.Thus,althoughthis
technology is promising significant advantages, it is often termed not robust, not
reliable, expensive, slow and inefficient and its implementation in real production
processesishindered.Toovercometheseobstaclesandtoexplorethefullpotential
of ultrashort laser pulses, the German Federal Ministry of Education and Research
(BMBF)haslauncheda comprehensiveresearchinitiative onultrashortpulse laser
technology.Thisincludesthedevelopmentofinnovative,inexpensiveandpowerful
newultrashortpulselasersystemsaswellastheappropriatesystemtechnologyfor
beam controland steering. Apartfrom the research on laser sources a strong focus
wasonthedevelopmentoftheinteractionprocessesitself,closelylinkedtospecific
v
vi Preface
application examples. This research effort has been pursued by 23 companies and
13 research institutions, which closely worked together within 9 joint research
projects. The research was supported with more than 24 million Euros by the
BMBF.Asimilaramountofmoneywasspentinadditionbytheindustrialpartners
involved.The major resultsofthis research initiative aresummarizedinthis book.
In order to provide a coherent picture, the individual contributions are grouped
thematically rather than by the original projects. Laser source development is
covered in the first section, followed by a section describing fundamental interac-
tion aspects, processing strategies as well as beam shaping, scanning and other
relevant system technology. Finally, specific applications from surgery, THz gen-
eration to electron source generation for X-ray sources complete the overview.
The remarkable progress in ultrashort pulse technology and its applications as
described here would not have been possible without the dedication of the com-
panies and institutes, especially the researchers involved, but also the generous
support by the German Federal Ministry of Education and Research. The editors
and authors of this book express their sincere thanks to all of these.
Stefan Nolte
Jena Frank Schrempel
Stuttgart Friedrich Dausinger
Contents
Part I Ultra Short Pulse Laser Sources
1 High Energy/High Repetition Rate Laser Pulses from Yb Based
Solid State Oscillators with Cavity-Dumping and Regenerative
Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Moritz Emons, Guido Palmer, Marcel Schultze, Uwe Morgner,
Hakan Sayinc, Dieter Wandt and Dietmar Kracht
1.1 Solid State Oscillators with Cavity-Dumping . . . . . . . . . . . . . 4
1.1.1 Solitary Regime in Bulk-Oscillators . . . . . . . . . . . . . 5
1.1.2 The Chirped Pulse Oscillator (CPO) . . . . . . . . . . . . . 6
1.1.3 Thin-Disk Oscillator in the Solitary Regime. . . . . . . . 7
1.1.4 Limits ofCavity-Dumping inThin-Disk Oscillators. . . 8
1.1.5 Chirped-Pulse Oscillator with Two Yb:KYW
Bulk Crystals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.1.6 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2 Regenerative Amplification with Yb:KYW and Yb:KLuW
Thin-Disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.3 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 High Power Femtosecond Diode Lasers. . . . . . . . . . . . . . . . . . . . 23
Thorsten Ulm, Florian Harth and Johannes L’huillier
2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2 Experimental Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.3 Mode-Locked Oscillators. . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3.1 Waveguide Saturable Absorbers . . . . . . . . . . . . . . . . 30
2.3.2 Pre-chirped Pulses. . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.3.3 Cavity Designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.4 Amplification of Mode-Locked Pulses. . . . . . . . . . . . . . . . . . 35
2.4.1 Gain Saturation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.4.2 Amplifier Performance . . . . . . . . . . . . . . . . . . . . . . 36
vii
viii Contents
2.5 Pulse Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.1 Self-colliding Pulse Mode-Locking (SCPML). . . . . . . 38
2.5.2 Colliding Pulse Mode-Locking (CPML). . . . . . . . . . . 40
2.6 Beam Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.7 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3 Femtosecond Mode-Locked Semiconductor Disk Lasers . . . . . . . . 47
Uwe Griebner, Peter Klopp, Martin Zorn and Markus Weyers
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.2 Semiconductor Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.2.1 Design, Growth, and Processing. . . . . . . . . . . . . . . . 50
3.2.2 Semiconductor Saturable Absorber Mirror . . . . . . . . . 51
3.2.3 SDL Gain Structure . . . . . . . . . . . . . . . . . . . . . . . . 54
3.3 Setup of the Mode-Locked Semiconductor Disk Laser. . . . . . . 57
3.4 Parameters for the Generation of Femtosecond Pulses
from Mode-Locked Semiconductor Disk Lasers . . . . . . . . . . . 57
3.4.1 Spectral Tuning of the SESAM . . . . . . . . . . . . . . . . 57
3.4.2 Dependence of Mode-Locked Laser Performance
on Pump-Power . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.4.3 Discussion—Mode-Locking Mechanism in SDLs . . . . 65
3.5 High Pulse Repetition Rates and Ultrashort Pulse Durations
from a Mode-Locked Semiconductor Disk Laser. . . . . . . . . . . 67
3.5.1 Sub-200-fs Pulses at 92 GHz Repetition Rate
in the Harmonically Mode-Locked Regime . . . . . . . . 67
3.5.2 107-fs Pulses at 5 GHz Repetition Rate in
the Fundamentally Mode-Locked Regime . . . . . . . . . 69
3.6 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4 Compact Ultrafast Oscillators and High Performance
Ultrafast Amplifiers Based on Ytterbium-Doped Fibers . . . . . . . . 75
J. Limpert, T. Eidam, M. Baumgartl, F. Röser, M. Plötner, B. Ortaç,
S. Nolte and A. Tünnermann
4.1 Introduction and Motivation. . . . . . . . . . . . . . . . . . . . . . . . . 75
4.2 Fundamentals of Short Pulse Propagation in Passive
and Active Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.3 Compact All-Fiber Femtosecond Mode-Locked Lasers. . . . . . . 79
4.4 High Average Power Femtosecond Fiber Amplifier. . . . . . . . . 85
4.5 High Pulse Energy Ultrafast Fiber Amplifier . . . . . . . . . . . . . 86
4.6 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Contents ix
5 Ultrafast Thin-Disk Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Oliver H. Heckl, Jochen Kleinbauer, Dominik Bauer, Sascha Weiler,
Thomas Metzger and Dirk H. Sutter
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.2 Overview of Disk Materials and Pulse Durations . . . . . . . . . . 96
5.3 Ultrafast Disk Oscillators. . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.4 Ultrafast Regenerative Thin-Disk Amplifiers . . . . . . . . . . . . . 103
5.5 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6 High-Average Power Ultrafast Yb:Innoslab-Amplifier . . . . . . . . . 117
Peter Russbueldt, Torsten Mans, Dieter Hoffmann
and Stefan Schippel
6.1 Yb:Innoslab Amplifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.1.2 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.1.3 Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
6.1.4 Experimental Results. . . . . . . . . . . . . . . . . . . . . . . . 122
6.1.5 Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
6.2 Optics Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.2.1 Optics for the fs Laser System . . . . . . . . . . . . . . . . . 128
6.2.2 Beam Splitter for Pump Light Coupling. . . . . . . . . . . 129
6.2.3 Polishing of YAG Substrates . . . . . . . . . . . . . . . . . . 131
6.2.4 Anti-reflective Coating of YAG and KGW. . . . . . . . . 132
6.2.5 Technology for the Production and Coating
of Slab Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
7 Few-Cycle Mid-Infrared OPCPA System. . . . . . . . . . . . . . . . . . . 135
Xun Gu, Yunpei Deng, Gilad Marcus, Thomas Metzger,
Reinhard Kienberger and Ferenc Krausz
7.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
7.2 Broadband OPA Phase-Matching Configurations. . . . . . . . . . . 138
7.3 MPQ/LMU LWS-1 System Description. . . . . . . . . . . . . . . . . 139
7.3.1 Infrared Seed Pulse Generation. . . . . . . . . . . . . . . . . 140
7.3.2 Nd:YLF Pump Laser. . . . . . . . . . . . . . . . . . . . . . . . 142
7.3.3 Stretcher and Compressor Design . . . . . . . . . . . . . . . 143
7.3.4 OPA Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7.3.5 OPCPA System Output and Parametric
Superfluorescence. . . . . . . . . . . . . . . . . . . . . . . . . . 146
7.3.6 Pulse Characterization. . . . . . . . . . . . . . . . . . . . . . . 148
7.4 Further Upgrade of the LWS-1 System . . . . . . . . . . . . . . . . . 149
7.5 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150