Adaptive polarization pulse shaping and modeling of light matter interactions with neural networks [Elektronische Ressource] / vorgelegt von Reimer Andreas Selle

AdaptivePolarizationPulseShaping
and
ModelingofLight–MatterInteractions
withNeuralNetworks
DissertationzurErlangungdes
naturwissenschaftlichenDoktorgradesder
Julius–Maximilians Universit at¨
Wurzb¨ urg
vorgelegtvon
ReimerAndreasSelle
ausHof
Wurzb¨ urg2007Eingereichtam: 16.November2007
¨ ¨beiderFakultatfurPhysikundAstronomie
1.Gutachter: Prof.Dr.T.Brixner
2. Prof.Dr.G.Gerber
derDissertation
1.Prufer:¨ Prof.Dr.T.Brixner
2.Prufer:¨ Prof.Dr.J.Geurts
3.Prufer:¨ Prof.Dr.W.Kinzel
imPromotionskolloquium
TagdesPromotionskolloquiums: 19.12.2007ListofPublications
T.Brixner,C.Dietl,G.Krampert,P.Niklaus,E.Papastathopoulos,T.Pfeifer,R.Selle,
G.Vogt,D.Walter,C.WinterfeldtandG.Gerber,
Adaptivefemtosecondquantumcontrol,
InF.Krausz,G.Korn,P.CorkumandI.A.Walmsley(Eds.),UltrafastOpticsIV,
Volume 95 of Springer Series in Optical Sciences, pp.119–128, Springer, Berlin
(2004).
T.Brixner,G.Krampert,T.Pfeifer,R.SelleandG.Gerber,
M.Wollenhaupt,O.Graefe,C.Horn,D.Liese,andT.Baumert,
Quantumcontrolbyultrafastpolarizationshaping,
Phys.Rev.Lett92[20],208301 1–208301 4(2004).
T.Brixner,G.Krampert,T.Pfeifer,R.SelleandG.Gerber,
M.Wollenhaupt,O.Graefe,C.Horn,D.Liese,andT.Baumert,
Adaptivepolarizationcontrolofmoleculardynamics,
In T. Kobayashi, T. Okada, T. Kobayashi, K. A. Nelson and S. DeSilvestri (Eds.),
UltrafastPhenomenaXIV,
VolumeXXofSpringerSeriesinChemicalPhysics,Springer,Berlin(2005).
G.Vogt,P.Nuernberger,R.Selle,F.Dimler,T.Brixner,andG.Gerber,
Analysisoffemtosecondquantumcontrolmechanismswithcoloreddoublepulses,
Phys. Rev. A74,033413 1–033413 8(2006).
P.Nuernberger,G.Vogt,R.Selle,S.Fechner,T.Brixner,andG.Gerber,
Generationoffemtosecondpulsesequencesintheultravioletbyspectralphasemodu
lation,
InJ.T.Sheridan,andF.Wyrowski(Eds.),PhotonManagementII,
ProceedingsofSPIE6187,No. 22,pp.151 162(2006)
P.Nuernberger,G.Vogt,R.Selle,S.Fechner,T.Brixner,andG.Gerber,
Generation of shaped ultraviolet laser pulses at the third harmonic of titanium–
sapphirefemtosecondlaserradiation,
Appl.Phys.B88,519–526(2007).
iR.Selle,G.Vogt,T.Brixner,G.Gerber,R.MetzlerandW.Kinzel
Modelingoflight–matterinteractionswithneuralnetworks,
Phys. Rev. A76,023810 1–023810 7(2007).
R.Selle,T.Brixner,T.Bayer,M.WollenhauptandT.Baumert
Modeling of ultrafast coherent strong field dynamics in potassium with neural net
works,
submitted(2007).
R.Selleetal.
Femtosecondpolarizationpulseshapingintheultraviolet,
inpreparation.
iiContents
ListofPublications i
1 Introduction 1
2 Quantumcontroloflight–matterinteractions 5
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Single–parametercontrol . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Optimalcontroltheory . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Adaptivequantumcontrol . . . . . . . . . . . . . . . . . . . . . . . 11
3 Technologicalconcepts 15
3.1 Mathematicaldescriptionoffemtosecondlaserpulses . . . . . . . . . 15
3.2 Generationoffemtosecondlaserpulses . . . . . . . . . . . . . . . . 20
3.3 Frequencyconversion . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3.1 Second–ordernonlinearopticaleffects . . . . . . . . . . . . . 24
3.3.2 Frequencydoublingofshapedlaserpulses . . . . . . . . . . 28
3.4 Femtosecondlaserpulseshaping . . . . . . . . . . . . . . . . . . . . 30
3.4.1 Phase–onlypulseshaping . . . . . . . . . . . . . . . . . . . 32
3.4.2 Polarizationlaserpulseshaping . . . . . . . . . . . . . . . . 34
3.5 Laserpulsecharacterization . . . . . . . . . . . . . . . . . . . . . . 46
3.5.1 FROGandXFROG . . . . . . . . . . . . . . . . . . . . . . . 46
3.5.2 Spectralinterferometry . . . . . . . . . . . . . . . . . . . . . 52
3.6 Jointtime–frequencyrepresentations . . . . . . . . . . . . . . . . . . 56
4 Quantumcontrolbyultrafastpolarizationshaping 59
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.2 Ionizationpathwaysanddynamicsinthepotassiumdimer . . . . . . 60
4.3 Pump–probeexperimentswithvaryingpolarizationconfigurations . . 64
4.4 QuantumcontrolofK . . . . . . . . . . . . . . . . . . . . . . . . . 672
4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5 PolarizationshapingintheUV 73
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.2 Experimentalimplementation . . . . . . . . . . . . . . . . . . . . . . 75
iii5.2.1 Thepolarizationpulseshaper . . . . . . . . . . . . . . . . . 77
5.2.2 Dual–channelspectralinterferometry . . . . . . . . . . . . . 78
5.2.3 Characterizationofthereferencepulse . . . . . . . . . . . . . 80
5.3 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6 Analysisoffemtosecondquantumcontrolmechanismswithdoublepulses 87
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.2 Generationofdoublepulses . . . . . . . . . . . . . . . . . . . . . . 90
6.3 Interpretationofcontrolmechanismswithfitnesslandscapes . . . . . 90
6.3.1 Experimentalsetup . . . . . . . . . . . . . . . . . . . . . . . 91
6.3.2 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . 92
6.4 Analysisoftheintrapulsedumpingmechanism . . . . . . . . . . . . 95
6.4.1 Experimentalsetup . . . . . . . . . . . . . . . . . . . . . . . 96
6.4.2 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . 97
6.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7 Modelingoflight–matterinteractionswithneuralnetworks 103
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7.2 Neuralnetworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.3 ModelingofSHGandmolecularfluorescencewithneuralnetworks . 107
7.3.1 SHGsimulation . . . . . . . . . . . . . . . . . . . . . . . . . 107
7.3.2 Experimentalimplementation . . . . . . . . . . . . . . . . . 109
7.3.3 Inputparametrizationandnetworkarchitecture . . . . . . . . 112
7.3.4 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . 116
7.4 Modelingofcoherentstrong–fielddynamicswithneuralnetworks . . 119
7.4.1 Simulationofthephysicalsystem . . . . . . . . . . . . . . . 121
7.4.2 Inputparametrizationandnetworkarchitecture . . . . . . . . 122
7.4.3 Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . 123
7.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8 Summary 131
9 Zusammenfassung 135
Bibliography 138
Acknowledgements 159
Lebenslauf 163
ivChapter1
Introduction
Godsaid:
1 μν
L = F F ,μν
4
O·D = ρ,
O·B = 0,
∂B
O×E+ = 0,
∂t
∂D
O×H = J+ .
∂t
Lettherebelight!
The presence of light, and hence warmth and energy, is one of the prerequisites for
life on Earth. Guided by evolution, nature developed molecules, cells and organisms
that can harvest the plentiful energy offered by our star, the Sun, with an astonishing
efficiencythatispossiblymatchedonlybytheirresiliencetophotophysicaldamage.
With the invention of the laser, the chemists’ dream to investigate, initiate and con
trolchemicalreactionsonthemolecularscaleseemedtocomewithingrasp. However,
the true beginnings of the realization of this dream had to wait until the time when
theboundariesonthedurationoflaserpulseswerepushedintothepicosecondtofem
tosecondregime,thenaturaltimescaleofnuclearmotions,i.e.,vibrationsandrotations
in molecules. While such light sources allowed, for the first time, the direct observa
tion of molecular dynamics, the breakthrough for the control of physical or chemical
processesontheatomicormolecularscalecamewiththeadventofpulseshapingtech
niquesthatmadeitpossibletomodifytheseultrashortpulses,andhencetoadaptthem
totheinvolveddynamics.2 Introduction
Especially the adaptive shaping of femtosecond laser pulses met great success,
as the control over a variety of physical and chemical processes, such as the bond–
selective dissociation or isomerization of molecules were successfully demonstrated
with this method. It is intriguing that – just as nature adapted its molecules and more
complexstructurestothepresentnaturallightsourcesbyevolution–itshouldbeevo
lutionaryalgorithmsthatweremostsuccessfulinadaptingtheartificial,coherentlight
of lasers to the dynamics of molecules, the building blocks of cells and organisms.
While the shaping of ultrashort laser pulses and the adaptive optimization of physical
orchemicalprocesseshavebecomewell–establishedtechniques,thesefieldsstillhold
avarietyoffascinatingpossibilities,opportunities,andchallenges.
One of the most puzzling chemical aspects of life is that it is chiral. Biologically
importantmolecules,suchasaminoacidsandproteins,appearinonlyonegeometrical
configuration in nature, while their mirror–symmetric partners are absent. In artifi
cal synthesis reactions however, both configurations (so–called enantiomers) of these
molecules can be produced. As the tragic events surrounding thalidomide, a molecule
used during the late 1950s and early 1960s in medicaments for pregnant women, il
lustrate,the‘wrong’enantiomercanhavedevastatingeffectsonbiologicalsystems,in
this case genetic damage to embryos. The enantiomer–selective prod