椭偏光场下锂原子共振激发过程(特邀)  

Resonance Excitation Process of Lithium Atoms in Elliptically Polarized Laser Fields(Invited)

作　　者：齐昕 郭丽 易小鹏 胡师林 陈京 Qi Xin;Guo Li;Yi Xiaopeng;Hu Shilin;Chen Jing(Department of Physics,Mathematics and Science College,Shanghai Normal University,Shanghai 200234,China;Institute of Applied Physics and Computational Mathematics,China Academy of Engineering Physics,Beijing 100088,China;Research Center for Advanced Optics and Photoelectronics,Department of Physics,College of Science,ShantouUniversity,Shantou 515063,Guangdong,China;Hefei National Research Center for Physical Sciences at the Microscale,School of Physical Sciences,University ofScience and Technology of China,Hefei 230026,Anhui,China;Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology,College of EngineeringPhysics,Shenzhen Technology University,Shenzhen 518118,China)

机构地区：[1]上海师范大学数理学院物理系,上海200234 [2]中国工程物理研究院北京应用物理与计算数学研究所,北京100088 [3]汕头大学理学院物理系先进光学与光子学研究中心,广东汕头515063 [4]中国科学技术大学物理学院合肥微尺度物质科学国家研究中心,安徽合肥230026 [5]深圳技术大学工程物理学院深圳市超强激光与先进材料技术重点实验室,广东深圳518118

出　　处：《光学学报》2024年第17期313-321,共9页Acta Optica Sinica

基　　金：国家重点研发计划(2019YFA0307700);国家自然科学基金(12274300)。

摘　　要：基于散射矩阵理论建立了在强激光场作用下电子从基态直接跃迁到里德伯态的量子理论模型。利用该模型计算研究了椭偏光场下锂原子被激发到不同里德伯态的概率随激光场椭偏率的变化。研究发现:当光强较低时,激发过程与微扰理论一致;但当光强较高时,激光场不仅使里德伯态的能级发生移动,而且对里德伯态的空间相位分布也产生了影响,进而改变了激发率随光场椭偏率的变化曲线。同时,计算结果也展现出椭偏场多光子激发过程中角动量和磁量子数跃迁选择定则特点:当共振激发过程吸收偶数或者奇数个光子时,初态与里德伯态的轨道角动量量子数(磁量子数)的奇偶性分别一致或者相反。Objective Strong-field Rydberg state excitation(RSE)is a significant physical phenomenon observed when atoms or molecules are exposed to intense laser fields.Numerous theoretical and experimental studies have explored the RSE process to understand its underlying physical mechanisms.However,existing theoretical methods,such as solving the time-dependent Schrödinger equation(TDSE),while accurately describing the physical process,do not provide a clear physical picture.Consequently,the mechanism of RSE,particularly in elliptically polarized laser fields,remains unclear.To better investigate the RSE in strong fields,we develop a quantum model for resonance excitation based on S-matrix theory.This model describes the electron transition from the ground state to the field-dressed Rydberg state in strong laser fields,allowing for a detailed investigation of the physical characteristics of strong-field RSE.Methods A quantum model based on S-matrix theory is developed to describe the transition of electrons from the ground state to the Rydberg state in intense laser fields,using the length gauge.Furthermore,we consider the effect of the intense laser field on the Rydberg state,treating the field-dressed Rydberg state as the final state within an elliptically polarized laser field characterized by a sine-square envelope containing 30 optical cycles.Results and Discussions We first use the quantum model to calculate the evolution of the excitation rates of the 4s,4p,4d,and 4f states at different laser intensities for laser pulses with an ellipticity of 0.5(Fig.1)and provide corresponding explanations.Next,we investigate the ellipticity-dependent excitation rates of different excited states at two laser intensities of 1.4×10^(12) W/cm^(2) and 6.82×10^(13) W/cm^(2).When the laser intensity is 1.4×1012 W/cm2(two-photon transition),the excitation rate of the 4s state decreases with increasing ellipticity,while the excitation rate of the 4d state increases(Fig.2).These findings are consistent with both TDSE results and the p

关 键 词：超快光学 场缀饰的里德伯态 多光子共振 散射矩阵理论 

分 类 号：O436[机械工程—光学工程]