科研之友
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摘要
A promising method is proposed to generate the intense ultrabroadband supercontinuum spectra and the ultrashort attosecond x-ray pulses from pre-excited He+ ion with the homogeneous and inhomogeneous two-color mid-infrared laser field combined with a unipolar pulse. For the homogeneous case, by optimizing the two mid-infrared pulses and the unipolar pulse, not only the harmonic cutoff has been extended, but also the harmonic modulation has been remarkably reduced. Moreover, we found the above harmonic extension scheme can be achieved in the multi-cycle pulse region and by preparing the initial state of He+ ion as the coherent superposition of the ground and the first excited states, the harmonic yield can be enhanced by 4-6 orders of magnitude compared with the case of the single ground initial state. Furthermore, with the introduction of the inhomogeneous of the combined field, the harmonic cutoff can be further enhanced, resulting in a supercontinuum with the bandwidth of 1648 eV. As a result, a series of intense 32as x-ray pulses can be obtained, which are 4-6 orders of magnitude improvement in comparison with the single initial state case.
- 出版日期2015-10
- 单位辽宁工业大学
