Femtosecond laser pulse shaping for enhanced ionization

被引:34
作者
Castro, A. [1 ,2 ,3 ,4 ]
Rasanen, E. [2 ,3 ,5 ]
Rubio, A. [1 ,6 ,7 ,8 ]
Gross, E. K. U. [2 ,3 ,9 ]
机构
[1] Max Planck Gesell, Fritz Haber Inst, D-14195 Berlin, Germany
[2] Free Univ Berlin, Inst Theoret Phys, D-14195 Berlin, Germany
[3] Free Univ Berlin, ETSF, D-14195 Berlin, Germany
[4] Inst Biocomputac & Fis Sistemas Complejos BIFI, E-50009 Zaragoza, Spain
[5] Univ Jyvaskyla, Dept Phys, Nanosci Ctr, FI-40014 Jyvaskyla, Finland
[6] Univ Basque Country, CSIC, Ctr Fis Mat, EHU MPC,Nano Bio Spect Grp,Dept Fis Mat, E-20018 San Sebastian, Spain
[7] Univ Basque Country, CSIC, Ctr Fis Mat, EHU MPC,Dept Fis Mat,ETSF Sci Dev Ctr, E-20018 San Sebastian, Spain
[8] DIPC, E-20018 San Sebastian, Spain
[9] Max Planck Inst Microstruct Phys, D-06120 Halle, Germany
基金
美国国家科学基金会;
关键词
HARMONIC-GENERATION; H-2(+); FIELD; DISSOCIATION; ULTRASHORT; DYNAMICS; OCTOPUS; RATES; H-2+; BOND;
D O I
10.1209/0295-5075/87/53001
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
We demonstrate how the shape of femtosecond laser pulses can be tailored in order to obtain maximal ionization of atoms or molecules. For that purpose, we have overlayed a direct-optimization scheme on top of a fully unconstrained computation of the three-dimensional time-dependent Schrodinger equation. The procedure looks for pulses that maintain the same total length and integrated intensity or fluence as a given pulse that serves as an initial guess. It allows, however, for changes in frequencies - within a certain, predefined range-and overall shape, leading to enhanced ionization. We illustrate the scheme by calculating ionization yields for the H-2(+) molecule when irradiated with short (approximate to 5 fs), high-intensity laser pulses. The magnitude of the obtained enhancement, as well as the shape of the solution optimal field depend strongly on the constrains imposed on the search space. In particular, when only small frequencies are allowed, the solution merely increases the peak intensity through temporal compression, as expected from a simple tunneling picture. If larger frequencies are allowed the structure of the solution field is more complicated. Copyright (C) EPLA, 2009
引用
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页数:6
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