强激光场中N_2分子高次谐波的干涉效应

Interference effects in high-order harmonic generation from N_2 molecules in intense laser fields

在强场近似下,利用Lewenstein模型研究了N_2分子在强激光场中发射高次谐波的干涉效应,通过对N_2分子产生的高次谐波和分子中单个原子产生高次谐波的比较,表明了干涉效应的存在.得出随着高次谐波阶数的增加,干涉极小值会随着分子轴与激光偏振方向间夹角的增加而减小,在角度接近90°附近时干涉效应消失,与两中心干涉模型预测的趋势一致.通过分析高次谐波产生的机制和相住随取向角的变化。给出了干涉产生的原因.

Within the strong field approximation (SFA),the interference effect from the high-order harmonic generation(HHG) of N_2 molecules are investigated by using Lewenstein model in intense laser field. Compared the result with the contribution from one nucleus of N_2 tit exhibits a minimum because of the interference effect. It is shown that the minimum decreases with the increasing order of HHG, while for 90° the interference effect vanishes,and the trend is agreement with the predictions of the two-centre interference model. In general,the presence of the interference is attributed to the generation of high-order harmonics and the change of the harmonic phase.