对近阈谐波短轨道抑制作为隧穿出口标志的检验

Test of Short-trajectory Suppression for Near-threshold Harmonics as a Tunneling Exit Sign

通过求解二维含时薛定谔方程的数值方法,研究了不同电离能的原子高次谐波产生。采用能够分辨出只有短电子轨道对高次谐波贡献的数值方案,随着激光波长的增大和激光强度的降低,结果表明:计算得到的短轨道高次谐波频谱在阈值附近出现了一个能量区,在这个能量区域,高次谐波的产生受到了明显的抑制;能量区域的宽度取决于靶的电离能。进一步分析表明:此能量抑制区归因于隧穿出口对短轨道高次谐波产生过程的影响,从而为研究隧穿的空间特性提供了一个可能的观测对象(独特的高次谐波产生特征),同时验证了此方法也适用于其他原子的隧穿出口,对近阈谐波短轨道抑制作为隧穿出口的标志进行了检验。

Through solving the two-dimensional time-dependent Schrödinger equation numerically,the highorder harmonic generation of atoms with different ionization potentials is studied.In this paper,a numerical scheme is used to distinguish the contribution of only short electron trajectory to HHG.With the increase of the laser wavelength and the decrease of the laser intensity,the calculated short-trajectory HHG spectra show an energy region near the threshold,where the HHG yields are suppressed strikingly.The width of the energy region depends on the ionization potential of the target.This suppression can be attributed to the effect of tunnel exit,by providing a possible observable HHG feature for studying tunneling.The results show that the energy suppression region is due to the influence of the tunneling exit,which provides a unique high-order harmonic generation feature for the study of tunneling.It also verifies that this method is applicable to other atoms.The short orbit suppression of nearthreshold harmonics as a sign of tunneling exit is tested.