Abstract
We present a theoretical study on coherent extreme ultraviolet (XUV) attosecond pulse amplification mediated by nonlinear parametric enhanced forward scattering occurring in the interaction of a strong femtosecond infrared (IR) laser pulse combined with a weak attosecond XUV pulse train with an atom. We predict large amplification of XUV radiation when the IR strong pulse and the XUV weak pulse are optimally phased. We study high-order harmonic processes (HHG) in He, He(+) and Ne(++), and show how although the HHG yield is largely affected by the particular atom used as target, nonlinear parametric XUV amplification is only weakly affected. We conclude that XUV nonlinear parametric attosecond pulse amplification can be most efficiently observed by using atoms with a high ionization potential and that the nonlinear amplification is robust at high photon energies where HHG is not efficient, such as in the water-window spectral region.
Highlights
The simultaneous illumination of atoms with an intense infrared (IR) pulse and a weak extreme ultraviolet (XUV) pulse has been suggested as a means for table-top coherent XUV radiation sources with shaped attosecond pulses [1, 2] and with high photon energies via selective yield enhancement [3] in high-order harmonic generation (HHG) processes
We present a theoretical study on coherent extreme ultraviolet (XUV) attosecond pulse amplification mediated by nonlinear parametric enhanced forward scattering occurring in the interaction of a strong femtosecond infrared (IR) laser pulse combined with a weak attosecond XUV pulse train with an atom
We study high-order harmonic processes (HHG) in He, He+ and Ne++, and show how the HHG yield is largely affected by the particular atom used as target, nonlinear parametric XUV amplification is only weakly affected
Summary
The simultaneous illumination of atoms with an intense infrared (IR) pulse and a weak extreme ultraviolet (XUV) pulse has been suggested as a means for table-top coherent XUV radiation sources with shaped attosecond pulses [1, 2] and with high photon energies via selective yield enhancement [3] in high-order harmonic generation (HHG) processes. By using the strong field approximation (SFA) [4] it was shown in [3] that the HHG energy yield can be enhanced in a particular region of the spectrum when a weak XUV pulse is correctly phased and combined with the IR intense pulse producing high-harmonics. In the present study we address the interaction of atoms with different ionization potentials, such as He, He+ and Ne++, with an intense infrared (IR) laser pulse combined with a weak extreme ultraviolet (XUV) pulse train. The later is specially relevant for x-ray spectroscopy techniques in medical and biological sciences As it will be shown, we observe how the HHG yield is largely affected by the particular ionization potential of the atom, stimulated processes from nonlinear parametric interactions are only weakly affected. Our simulations predict that XUV nonlinear parametric pulse amplification can be efficiently produced in the water-window spectral region, where the efficiency of HHG is poor
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