摘要
We present an efficient and realizable scheme for the generation of an ultrashort single attosecond（as） pulse from H atom with a 800-nm fundamental laser field combined with a terahertz（THz） field. The high-order harmonic generation（HHG） can be obtained by solving the time-dependent Schr dinger equation accurately and efficiently with time-dependent generalized pseudo-spectral（TDGPS） method. The result shows that the plateau of high-order harmonics is extended and the broadband spectra can be produced by the combined laser pulse, which can be explained by the corresponding ionization probability. The time–frequency analysis and semi-classical three-step model are also presented to further investigate this mechanism. Besides, by the superposition of the harmonics near the cutoff region, an isolated 133-as pulse can be obtained.
We present an efficient and realizable scheme for the generation of an ultrashort single attosecond（as） pulse from H atom with a 800-nm fundamental laser field combined with a terahertz（THz） field. The high-order harmonic generation（HHG） can be obtained by solving the time-dependent Schr dinger equation accurately and efficiently with time-dependent generalized pseudo-spectral（TDGPS） method. The result shows that the plateau of high-order harmonics is extended and the broadband spectra can be produced by the combined laser pulse, which can be explained by the corresponding ionization probability. The time–frequency analysis and semi-classical three-step model are also presented to further investigate this mechanism. Besides, by the superposition of the harmonics near the cutoff region, an isolated 133-as pulse can be obtained.
基金
Project supported by the National Natural Science Foundation of China(Grant Nos.11174108,11104108,and 11271158)
