Table Of ContentLaser Interactions with Atoms,
Solids, and Plasmas
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SeriesB: Physics
Laser Interactions with Atoms,
Solids, and Plasmas
Edited by
Richard M. More
Lawrence Livermore National Laboratory
Livermore,California
Springer Science+Business Media, LLC
Proceedings01aNATOAdvanced Study Instituteon
LaserInteractionswithAtoms, Solids, and Plasmas,
held August 17-25, 1992,
in Carpäse, Corsica,France
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Laser interactions with atoms. sollds. and plasmas ( edited by Rlchard
M. More.
p. cm. -- (NATO ASI serles. Series B. PhYS1CS : v, 327)
"Published 1n cooperatlon wlth NATO Scientific Affalrs Division."
"Proceed1ngs of a NATO Advanced Study Institute on Laser
Interactions with Atoms. So11ds. and Plasmas. held August 17-25,
1992. in Cargise. Corslc3. France."
Includes blbl10graphical references and index.
1. Laser manipulation <Nuclear physlcs)--Congresses. 2. Atoms
-Congresses. 3. So11ds--Effect of radiation on--Congresses.
4. Laser-plasma lnteractlons--Congresses. 5. Laser pulses.
Ultrashort--Congresses. 6. High power lasers--Congresses.
I. More. Rlchard M. 11. North Atlantic Treaty Organization.
Scientific Affairs DivIsion. 111. NATO Advanced Study Institute on
Laser Interact10ns wlth Atoms. So11ds. and Plasmas (1992 Cargese.
France) IV. Series.
OC689.5.L35L37 1994
539.7·23--dc20 94-30897
CIP
ISBN 978-1-4899-1578-8 ISBN 978-1-4899-1576-4 (eBook)
DOI 10.1007/978-1-4899-1576-4
©1994SpringerScience+BusinessMedia NewYork
Originallypublished byPlenum Press, NewYorkin1994.
Softcoverreprint ofthehardcover1stedition 1994
All rights reserved
No partof this book may be reproduced, stored inaretrievalsystem, or transmilled inany
form or by any means, electronic,mechanical, photocopying,microfilming,recording, or
otherwise,withoutwrillenpermissionfrom the Publisher
PREFACE
Theaim ofthis NATO AdvancedStudyInstitutewas to bring togetherscientists and
students working in the field oflaser matter interactions in order to review and stimulate
developmentoffundamentalsciencewith ultra-shortpulse lasers.
New techniquesofpulse compression and colliding-pulsemode-locking have made
possiblethe constructionoflasers with pulselengthsin thefemtosecondrange.Such lasers
are now in operation at several research laboratories in Europe and the United States.
These laser facilities present a new and exciting research direction with both pure and
applied science components. In this ASI the emphasis is on fundamental processes
occurring in the interaction of short laser pulses with atoms, molecules, solids, and
plasmas.
In the case of laser-atom (molecule) interactions, high power lasers provide the
first access to extreme high-intensity conditions above 10'8 Watts/em', a new frontier for
nonlinear interaction of photons with atoms and molecules. New phenomena observed
include multiphotonionizationprocesses,atomiccollisionsinthe presenceofastrong laser
field, Coulomb explosion following rapid ionization of a molecule and the production of
high harmonics of the laser source. Another important topic reviewed in this ASI is the
lasercoolingofatoms.
Short-pulse lasers are also able to heat solid targets rapidly compared to target
evaporationor explosion. As aresult, hot mattercan beproducedat temperatures up to 10'
Kelvin with a precisely known density, the original solid density. With rapid diagnostics
also triggered bythe laser,itbecomespossibletomake accurate measurementsofelectrical
and radiative properties ofmatter at specified conditions ofextreme high energy-density.
These measurements have great importance for applications in pulsed power, plasma
physics, fusion research, high-velocity impacts and shock-wave physics while at the same
time providing an experimental stimulus to the fundamental statistical mechanics of hot
(astrophysical)matter.
The ASI summarized in this book aimed to review, systematize and solidify this
newfrontieroflaser-matterinteraction.
The organizing committee includedDr. R. More ofLivermore, Prof. R. Marrus of
DC Berkeley,Prof. C. Joachain ofthe Free University ofBruxelles and Prof. E. Fabre of
the Ecole Polytechnique in Palaiseau, France. Financial support for the school was
provided by the NATO Division of Scientific and Environmental Affairs. Additional
support was provided by the U.S. National Science Foundation and the Scientific and
Technical Research Council of Turkey. The participants were very grateful for this
support,and to the Institutd'EtudesScientifiquesde Cargeseand Mme. M.-F. Hanselerfor
the excellent accomodations and warm hospitality which helped us to hold a memorable
summerschool.
v
CONTENTS
HighIntensityLasers 1
A. Mysyrowicz
RecentAspectsofMultiphotonIonizationofAtoms......................................... 11
P.AgostiniandE.Mevel
TheoryofLaser-AtomInteractions....................................................................... 39
C.J.[oachain
HarmonicGenerationatHighIntensities............................................................ 95
K.J.Schafer,J.L. KrauseandK. C. Kulander
ComparisonofKineticEnergyDistributionsofC2+IonicFragments
InducedbyMultiphotonIonizationandFastIonImpactfromCO2.. 107
T.S.Luk,K. BoyerandC.K. Rhodes
ResonantDegenerateFour-WaveMixing............................................................ 113
D.Kupiszewska
SemiclassicalCalculationofAtomicProcesses . 123
RM.More
ExperimentsonRydbergWavePackets 163
L. D.Noordam,A. tenWoldeandH. B.vanLindenvandenHeuvell
LaserManipulationofNeutralAtoms 193
A.Aspect
SecondHarmonicProductionfromSolidTargets 207
D. vonderLinde
RamanStudyofLaser-InducedStructureModificationsofIon-Amorphized
Silicon.......................................................... 239
L. P. Avakyants,G.D.Ivlevand E.D. Obraztsova
PropertiesofCondensedMatterUnderPlanetaryInteriorConditions
MeasuredbyFemtosecondSpectroscopy................................................ 249
M.C. Downer,H.Ahn,D.H. Reitze,D.M.Riffe andX.-Y.Wang
vii
AbsorptionSpectroscopyofCompressedMatter............................................... 273
T.A. Hall
Density FunctionalandNonequilibriumMethodsforUnusualStatesof
MatterProducedUsingShort-PulseLasers............................................. 311
C.Dharma-Wardana
TheoryofComplexSpectrafrom LaserPlasmas................................................ 325
J.BaucheandC. Bauche-Amoult
InfluenceofthePrepulseontheX-rayYieldofaSubpicosecond
Laser-ProducedPlasma.............................................................................. 357
J.C.Gauthier,A. Rousse,F.Fallies, J.-P.Geindre,P.Audebert,
A. Mysyrowicz,G.Grillon,J.-P.ChambaretandA. Antonetti
ModelCalculationsof H-like RecombinationSchemes..................................... 367
L. Bonnet
TheoryofPlasmaWaveAbsorption..................................................................... 383
P.Mulser
ParametricInstabilitiesin PicosecondTimeScales............................................. 437
H.Baldis,W.Rozmus,C.Labaune,Ph.Mouniax,D.Pesme,
S.BatonandV.T.Tikhonchuk
Index 475
viii
HIGH INTENSITY LASERS
AndreMysyrowicz
Laboratoired'OptiqueAppliquee
ENSTA,EcolePolyteehnique
91120Palaiseau,France
INTRODUCTION
As will be evidentfrom the content of this book, a new fascinating
subfield of physics is developing which deals with the interaction of
matter with very intense radiation. By very intense radiation one
understands a regime such that the electric field associated with the
radiation is comparable or exceeds the internal Coulomb field tying
electrons to the atomic nucleus. It corresponds to electric fields of the
order or beyond 1010V/cm or light intensities above 1017 W/cm2. Such
intense fields can be now routinely obtained with relatively modest means
well within the reach of small academic institutions. The breakthrough
allowing this state of affairs is the development of lasers emitting
ultrashort pulses, a few tens femtoseconds (10-15 sec.) in duration. Since
instantaneouspeak intensity corresponds to light energy divided by pulse
duration, it is clear that an enormous reduction in the scale of operation
and associated costs is achieved if one compares such lasers with more
conventional nanosecond pulsed laser systems with the same peak
intensity. A visible light pulse ofduration 100 fs (10-13 s), when focussed
close to the diffraction limit, requires only 100 mJ of energy to deliver a
peak intensity of 1019 W/cm2. Another attractive feature of these new
laser sources is their high repetition rate. They run typically at 20-50
hertz, allowing a measurement of the time evolution of reproducible
phenomenawith subpicosecond accuracy via all-optical pump-and -probe
detection techniques.
The purpose of this chapter is to introduce for the uninitiated the
basic principles underlying femtosecond pulse generation and
amplification. It is beyond the scope ofthis introduction to give a detailed
LaserInteractionswithAtoms.Solids.andPlasmas
Edited by R.M.More.PlenumPress.NewYork.1994
and accurate description of the state ofthe art in a fast evolving field. For
a more exhaustive description, the interested reader is referred to the
proceedings of topical meetings on the subject, such as the annual
conference on Ultrafast Phenomena and to ref 1). Likewise, there will be
no discussion concerning the present effort aimed at upconverting
classical high energy laser installations based on Nd:glass technology by
reducing the pulse duration to the picosecond time scale.
FEMTOSECOND LASER OSCILLATOR
We consider a light source with inverted population, emitting in a
random fashion into a large number of radiation modes. Such a
broadband light amplifier, typically obtained by a dye such as Rhodamine
60 pumped with a cw Argon laser emits a chaotic radiation field due to
the incoherent superposition of many radiation modes. This chaotic field
contains spikes of intensity corresponding to the fortuitous additive
superposition ofa large number of radiation modes. The typical duration
of these spikes is of the order of the inverse spectral bandwidth of the
source. This is schematically represented in figure 1.
Consider now the action of a fast saturable absorber with fast
recovery time, opaque to low input light intensities but transparent to
high intensities, as shown schematically in figure 2. If both the light
emitter and saturable absorber are put in a cavity capable of
accomodating many longitudinal modes of radiation, pulse shaping will
take place inside the cavity.The randomly generated initial spike of short
duration is transmitted through the saturable absorber, then amplified
when crossing the optical amplifier, whereas the rest of the emission is
attenuated. As a result, after several roundtrips in the cavity, pulse
shaping has taken place and a stable mode ofoperation has been achieved,
whereby a train ofshort pulses are emitted by the oscillator, with a pulse
duration of the order of l/dw (where dw is the spectral width of the
optical gain) and a separation between pulses equal to the roundtrip time
in the cavity. Lasers emitting a train ofshort pulses due to the locking of
a large number of modes to a common phase are called mode-locked
lasers.
time Incidentlightintensity
Figure 1. Schematic representation of a Figure 2) Transmission characteristics of a
chaotic field resulting from the superposition saturable absorber with high losses for low
of many radiation modes. The horizontal incident intensities but low losses at high
dashedlineindicatesthethresholdintensityfor incidentintensities.
thesaturableabsorber.
2
