中国物理B ›› 2023, Vol. 32 ›› Issue (11): 113201-113201.doi: 10.1088/1674-1056/ace317

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Role of excited states in helium-like ions on high-order harmonic generation

Jiang-Hua Luo(罗江华) and Jia-Jun Xiao(肖佳俊)   

  1. School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, China
  • 收稿日期:2023-05-10 修回日期:2023-06-22 接受日期:2023-06-30 出版日期:2023-10-16 发布日期:2023-10-16
  • 通讯作者: Jiang-Hua Luo E-mail:jhluo09@qq.com
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12274294 and 12075036).

Role of excited states in helium-like ions on high-order harmonic generation

Jiang-Hua Luo(罗江华) and Jia-Jun Xiao(肖佳俊)   

  1. School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, China
  • Received:2023-05-10 Revised:2023-06-22 Accepted:2023-06-30 Online:2023-10-16 Published:2023-10-16
  • Contact: Jiang-Hua Luo E-mail:jhluo09@qq.com
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12274294 and 12075036).

摘要: We theoretically investigate high-order harmonic generation (HHG) of helium (He), lithium cation (Li+), and beryllium dication (Be2+) using the time-dependent Hartree-Fock method to solve the three-dimensional time-dependent Schrödinger equation. It is found that the intensity of the HHG increases significantly from a certain harmonic order below the ionization threshold, and the initial position of the enhancement does not depend on the intensity or the wavelength of the driving laser field. Further analysis shows that excited states play an important role on this enhancement, consistent with the excited-state tunneling mechanism [Phys. Rev. Lett. 116 123901 (2016)]. Our results unambiguously show that excited-state tunneling is essential for understanding the enhancement of HHG. Accordingly, a four-step model is herein proposed to illustrate the multiphoton excitation effect in helium-like ions, which enriches the physics of HHG enhancement.

关键词: high-order harmonic generation, ultrafast phenomena, excited states

Abstract: We theoretically investigate high-order harmonic generation (HHG) of helium (He), lithium cation (Li+), and beryllium dication (Be2+) using the time-dependent Hartree-Fock method to solve the three-dimensional time-dependent Schrödinger equation. It is found that the intensity of the HHG increases significantly from a certain harmonic order below the ionization threshold, and the initial position of the enhancement does not depend on the intensity or the wavelength of the driving laser field. Further analysis shows that excited states play an important role on this enhancement, consistent with the excited-state tunneling mechanism [Phys. Rev. Lett. 116 123901 (2016)]. Our results unambiguously show that excited-state tunneling is essential for understanding the enhancement of HHG. Accordingly, a four-step model is herein proposed to illustrate the multiphoton excitation effect in helium-like ions, which enriches the physics of HHG enhancement.

Key words: high-order harmonic generation, ultrafast phenomena, excited states

中图分类号:  (Multiphoton ionization and excitation to highly excited states)

  • 32.80.Rm
31.90.+s (Other topics in the theory of the electronic structure of atoms and molecules) 32.80.Fb (Photoionization of atoms and ions)