High-order harmonic generation of Li ⁺ with combined infrared and extreme ultraviolet fields

Abstract

We investigate high-order harmonic generation (HHG) of Li + ion driven by an intense infrared (IR) laser field in combination with a weak XUV pulse. To achieve this, we first construct an accurate single-active electron angular-momentumdependent model potential of Li + ion, by which the accurate singlet energy levels of Li + for the ground state and excited states with higher quantum numbers can be obtained. Then, we solve numerically the three dimensional time-dependent Schrödinger equation of Li + ion by means of the generalized pseudospectral method to obtain HHG. Our results show that the strength of assisted XUV is not amplified during the harmonic generation process, but the yield of HHG power spectrum in the whole plateau has a significant enhancement. Furthermore, the optimal phase delay between the IR and XUV pulses allows the production of ultrabroadband supercontinuum spectra. By superposing some harmonics, a strong new single 27-attosecond ultrashort pulse can be obtained.

Extreme-ultraviolet coherent pulse amplification in argon

“…In Ref. [20] IXPA processes were not achieved using 3D-TDSE simulations in Li + , which were indeed described with a 1D-TDSE model in Ref. [17] and have been now confirmed in argon with 3D-TDSE.…”

“…This improvement is key for the use of table-top coherent XUV and x-ray sources in many applications [1,2]. In particular, simultaneous excitation of atoms with an intense infrared (IR) driving pulse and a weak XUV pulse or train of pulses conveniently synchronized has been extensively investigated both theoretically and experimentally as a method to amplify the signal from the single-atom level interaction and also considering the effects of propagation [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

“…[19] and amplification any distant from the ionization threshold as observed in the experiments is there missing. A single-electron theoretical study has also been reported in the basis of angular momentum dependent potentials for the Li + ion and a comparison between onedimensional (1D) and three-dimensional (3D) simulations has been performed [20], although no intent to compare to the experimental results is realized.…”

Low-order harmonic generation of hydrogen molecular ion in laser field studied by the two-state model

“…The high-order harmonic generation (HHG) that results from the interaction of intense laser field with atoms, ions, and molecules, is a non-linear process during which the medium will emit the high harmonics of the generation beam. During the past few years, most researchers have focused on the harmonics at the plateau and near the cutoff region [1][2][3][4][5][6][7][8] owing to their important applications (e.g., they render technologies for the extreme-ultraviolet and soft-x-ray sources on the attosecond time scale), which leads to the observation and control of their dynamic electronic behaviors. [9][10][11][12] As research moves on, near-and below-threshold harmonics have also aroused attention.…”

Fiend -- Finite Element Quantum Dynamics

“…In these fields, the nonlinear interaction of the atomic or molecular electron with the driving laser field requires fast and accurate integration of the 3D time dependent Schrödinger equation (TDSE). Recent applications include, e.g., benchmarking of approximate models [1][2][3][4][5][6], study of high-order harmonic generation [7][8][9], and the study of photoionization [10][11][12][13][14].…”