By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with di...By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.展开更多
Bichromatic circularly polarized fields provide a useful tool to probe the ionization dynamics.In this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different helicities.Th...Bichromatic circularly polarized fields provide a useful tool to probe the ionization dynamics.In this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different helicities.The spectral features are analyzed with semiclassical trajectories derived from the strong field approximation.In particular, the interference fringes in momentum distribution are investigated by tracking the ionization time and tunneling exits of released photoelectrons.Different types of trajectories that contribute to the interference fringes are elucidated.展开更多
The photoelectron momentum distribution of H＋ in circularly polarized laser fields is studied based on classical trajectory calculations. We screen Coulomb potentials at different radii, and trace trajectories of an ...The photoelectron momentum distribution of H＋ in circularly polarized laser fields is studied based on classical trajectory calculations. We screen Coulomb potentials at different radii, and trace trajectories of an ensemble of electrons in such screened Coulomb potentials and circularly polarized laser fields. Simulations show that electron trajectories are bent by Coulomb fields, resulting in the laser-intensity-dependent drift of photoelectron momentum distributions in the laser polarization plane. This study intuitively explains how Coulomb potentials modify photoelectron momenta.展开更多
This paper proposes a modified strong field approximation model for evaluating nondipole effects on the ionization of an atom in an intense laser field. The photoelectron longitudinal momentum distributions （PLMD） o...This paper proposes a modified strong field approximation model for evaluating nondipole effects on the ionization of an atom in an intense laser field. The photoelectron longitudinal momentum distributions （PLMD） of a hydrogen-like atom exposed to a mid-infrared laser field is calculated. The theoretical results indicate an obvious asymmetry in the PLMD, and an offset of the PLMD peak appears in the opposite direction of the beam propagation due to nondipole effects. The peak offsets of the PLMD increased with the laser intensity, imposed by the initial state of the hydrogen-like atom.展开更多
The carrier envelope phase（CEP） has a direct impact on the physical properties of an isolated attosecond pulse（IAP） and many strong field processes,but it is difficult to measure in reality.Aiming at obtaining mor...The carrier envelope phase（CEP） has a direct impact on the physical properties of an isolated attosecond pulse（IAP） and many strong field processes,but it is difficult to measure in reality.Aiming at obtaining more accurate and complete characterization of CEP,we numerically investigate the annular photoelectron momentum spectra of the hydrogen atom ionized by overlapped fields of an IAP and an infrared（IR） pulse.By defining an overlapping parameter,the momentum patterns are classified and optimized for unambiguously measuring the rotation angle of a momentum pattern versus the CEP value.A series of simulations verify its robustness.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11271158,11574117,and 61575077)the Natural Science Foundation of Jilin Province of China(Grants No.20180101225JC)
文摘By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11420101003,11604347,11827806,11874368,61675213,and 91636105)
文摘Bichromatic circularly polarized fields provide a useful tool to probe the ionization dynamics.In this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different helicities.The spectral features are analyzed with semiclassical trajectories derived from the strong field approximation.In particular, the interference fringes in momentum distribution are investigated by tracking the ionization time and tunneling exits of released photoelectrons.Different types of trajectories that contribute to the interference fringes are elucidated.
基金supported by the National Natural Science Foundation of China(Grant Nos.11104180,11175120,11121504,and 11322438)the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(Grant No.131010)
文摘The photoelectron momentum distribution of H＋ in circularly polarized laser fields is studied based on classical trajectory calculations. We screen Coulomb potentials at different radii, and trace trajectories of an ensemble of electrons in such screened Coulomb potentials and circularly polarized laser fields. Simulations show that electron trajectories are bent by Coulomb fields, resulting in the laser-intensity-dependent drift of photoelectron momentum distributions in the laser polarization plane. This study intuitively explains how Coulomb potentials modify photoelectron momenta.
基金Project supported by the National Natural Science Foundation of China(Grant No.11274149)the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology,China(Grant No.F12-254-1-00)
文摘This paper proposes a modified strong field approximation model for evaluating nondipole effects on the ionization of an atom in an intense laser field. The photoelectron longitudinal momentum distributions （PLMD） of a hydrogen-like atom exposed to a mid-infrared laser field is calculated. The theoretical results indicate an obvious asymmetry in the PLMD, and an offset of the PLMD peak appears in the opposite direction of the beam propagation due to nondipole effects. The peak offsets of the PLMD increased with the laser intensity, imposed by the initial state of the hydrogen-like atom.
基金supported by the National Natural Science Foundation of China(Nos.11674243 and 11674242)the Fundamental Research Funds for the Central Universities(No.3122016D029)
文摘The carrier envelope phase（CEP） has a direct impact on the physical properties of an isolated attosecond pulse（IAP） and many strong field processes,but it is difficult to measure in reality.Aiming at obtaining more accurate and complete characterization of CEP,we numerically investigate the annular photoelectron momentum spectra of the hydrogen atom ionized by overlapped fields of an IAP and an infrared（IR） pulse.By defining an overlapping parameter,the momentum patterns are classified and optimized for unambiguously measuring the rotation angle of a momentum pattern versus the CEP value.A series of simulations verify its robustness.
