外加静电场对O_(2)分子高次谐波的调制机制(特邀)  

Understanding Effects of Static Electric-field on High-order Harmonic Generation of O_(2) Molecules(Invited)

作　　者：迟晨阳 郭迎春[1] 王兵兵[2,3] CHI Chenyang;GUO Yingchun;WANG Bingbing(School of Physics and Electronic Science,East China Normal University,Shanghai 200241,China;Beijing National Laboratory of Condensed Matter Physics,Laboratory of Optical Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]华东师范大学物理与电子科学学院,上海200241 [2]中国科学院物理研究所北京凝聚态物理国家研究中心光物理重点实验室,北京100190 [3]中国科学院大学,北京100049

出　　处：《光子学报》2024年第6期48-60,共13页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.12074418,11774411,92250303)。

摘　　要：采用了Lewenstein强场近似方法,计算了外加静电场对O_(2)分子在线偏振激光场中高次谐波产生的影响。结果表明:1)当静电场方向平行激光偏振方向时,谐波谱出现双平台结构,截止频率增大,偶次和奇次谐波幅度相当;2)当静电场方向垂直时,谐波谱呈现单平台结构,偶次谐波比奇次谐波的幅度小两个量级左右;3)外加静电场对双心干涉极小值的位置基本没有影响。利用Lewenstein理论,可以将分子谐波谱视为分子两端电离通道产生谐波的叠加,对外加静电场控制高次谐波提供了参考。High-order Harmonic Generation(HHG)is an important phenomenon caused by the interaction between lasers and atoms or molecules.It is of great significance to attosecond physics.The mechanism of HHG is well understood in terms of the“three-step”model.Applying an external static electric field is an important method for modulating high-order harmonic generation.The external static electric field can cause atoms or symmetric molecules to generate even-order harmonics.Even-order harmonics have different characteristics from odd ones.For instance,the yield of even harmonics exhibits a linear relationship with the intensity of the external static electric field within a specific field intensity range.This property can be utilized to measure the waveform of terahertz electromagnetic fields.The external static electric field is also often used to extend the plateau of high-order harmonics and generate shorter attosecond pulses.The high-order harmonic spectrum of polar molecules in the presence of an external electric field is found to exhibit a double-plateau structure related to the orientation of the molecules,making it possible to measure the orientation degrees.All of these applications inspire a deep understanding of how external static electric fields affect high-order harmonic generation.In this paper,Lewenstein's strong field approximation method is used to obtain the high-order harmonic spectrum of the O_(2) molecule in a linearly polarized laser field combined with an external static electric field.The polarization direction of the linearly polarized laser field is at a 45 degree angle to the molecular nuclear axis.The amplitude of the external static electric field is one-tenth of the laser amplitude.Two types of external static electric fields are examined in this paper.One type is a parallel static electric field whose field direction aligns with the direction of the laser polarization;The other type is a vertical static electric field whose field direction is perpendicular to the direction of the laser p

关 键 词：O_(2)高次谐波 外加静电场 谐波相位分析 双平台 奇偶谐波 

分 类 号：O437[机械工程—光学工程]