多周期双色场方案下附加脉冲频率对阿秒脉冲产生的影响

Effects of additional pulse wavelength at different frequencies on attosecond pulse generation in multicycle two-color laser field

通过数值求解一维含时薛定谔方程,研究了多周期双色场与氢原子相互作用过程中不同波段的附加脉冲波长对体系高次谐波及阿秒脉冲产生的影响.研究发现,当双色场的附加脉冲波长处于红外波段1600 nm时,比起处于可见光波段的533 nm附加脉冲,谐波谱截止位置得到大幅延展,相应地拓宽了超连续带宽,小波变换后获得了78 as的孤立短脉冲.由合成电场的光学振荡频率解释了附加脉冲波段对谐波谱的影响,同时该结论有利于在获得孤立阿秒脉冲的研究中选择合适的附加脉冲频率.

We theoretically investigate the effects of additional pulse wavelength at different frequencies on attosecond pulse generation from the hydrogen atom exposed to multicycle two-color laser field, by numerically solving the one-dimensional time-dependent Schrodinger equation. The results show that when the wavelength of the additional pulse is set to be 1600 nm, the cutoff position of the harmonic spectra is extended dramatically compared with the scenario in the case of 533 nm pulse in visible waveband, accordingly the bandwidth of supercontinuum is widened, finally 78 attosecond pulse is obtained by wavelet transform. In this paper, we explain the effects of additional pulse wavelength in different wavebands on high order harmonic generation for the first time according to the optical oscillation frequency of the synthesized field. Also, such a result is conducible to choosing the appropriate additional pulse frequency in order to obtain the isolated attosecond pulse.