通过数值求解一维含时薛定谔方程,本文研究了高频阿秒脉冲对拉伸双原子分子模型与低频飞秒激光脉冲相互作用产生高次谐波谱的影响.研究表明,若阿秒脉冲在低频脉冲的第二个光学周期截止处注入时,只第二个平台截止位置Ip+5.6Up(Ip为电离势,Up为有质动力能)附近谐波的效率得到显著提高;若阿秒脉冲的包络峰值处于低频脉冲第三个光学周期T/4(为飞秒激光脉冲的光学周期)附近时,则谐波谱出现了明显的整体抬高现象.对此,本文根据拉伸分子谐波谱的四种产生机制及阿秒脉冲在飞秒激光不同相位注入时的电子电离曲线,对这些谐波谱的结构给出了合理解释.
We investigate the influence of the high-frequency attosecond pulse on the high-order harmonic generation (HHG) spectra from a stretched diatom molecule model exposed to a low-frequency femtosecond(fs) pulse, by numerically solving a one-dimensional time-dependent Schrodinger equation. It is shown that, when the attosecond pulse is added to the end of the second T ( T is the optical cycle of fs pulse), the harmonic emission efficiencies near the second plateau cutoff Ip + 5.6 Up( Ip is the ionization potential and Up is the ponderomotive energy) can be effectively enhanced; when the attosecond pulse is set to the T/4 phase of the third T, the all harmonic plateaus could be heighten. For these particular structures of the harmonic spectra, we give reasonable explanation according to four kinds of harmonic generation mechanics and electronic ionization property in molecules.