Subcycle spectral structures and dynamics of high-order harmonic generation(HHG)processes of atoms and molecules driven by intense laser fields on the attosecond time scale have been originally studied theoretically a...Subcycle spectral structures and dynamics of high-order harmonic generation(HHG)processes of atoms and molecules driven by intense laser fields on the attosecond time scale have been originally studied theoretically and ex-perimentally.However,the time scale of HHG dynamics in crystals is in the order of sub-femtosecond,and the carrier dynamics of HHG in crystals driven by subcycle laser pulses are largely unexplored.Here we perform a theoretical study of subcycle structures,spectra,and dynamics of HHG of crystals in mid-infrared laser fields subject to excitation by a subcycle laser pulse with a time delay.The HHG spectra as a function of time delay between two laser fields are cal-culated by using a single-band model for the intra-band carrier dynamics in crystal momentum space and by solving the time-dependent Schr?dinger equation in velocity gauge for the treatment of multi-band crystal systems.The results exhibit a complex time-delay-dependent oscillatory pattern,and the enhancement and suppression of the HHG related to subcycle pulse are observed at the given time delay in either single-band or multi-band crystal systems.To understand oscillation structures with respect to the dependence for the subcycle laser fields,the time-frequency characteristics of the HHG as well as the probability density distribution of the radiation are analyzed in detail.展开更多
Exploiting the infinite-order continuous dynamical rotational symmetry of circularly or elliptically polarized classical light pulses,we establish the conservation law between the angular momentum and energy in strong...Exploiting the infinite-order continuous dynamical rotational symmetry of circularly or elliptically polarized classical light pulses,we establish the conservation law between the angular momentum and energy in strong-field ionization that is applicable at the subcycle level.We illustrate the conservation law through the correlated spectrum of angular momentum and energy of photoelectrons,both at the tunnel exit and in the asymptotic region.Moreover,we propose a protocol based on electron vortices to directly visualize the existence of the subcycle conservation law.Our work paves the pathway toward a deeper understanding of fundamental light-matter interactions on the subcycle scale.展开更多
With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our resu...With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our results show that the recollision time window can be precisely controlled within an isolated time interval of several hundred attoseconds, which is useful for understanding the subcycle correlated electron dynamics. More interestingly, the correlated electron momentum distribution (CEMD) exhibits a strong dependence on laser intensity. That is, at lower laser intensity, CEMD is located in the first quadrant. As the laser intensity increases,CEMD shifts almost completely to the second and fourth quadrants, and then gradually to the third quadrant.The underlying physics governing the CEMD's dependence on laser intensity is explained.展开更多
Using a classical ensemble method, we have investigated sequential double ionization (SDI) of Ar atoms driven by elliptical laser pulses. The results show that the ion momentum distribution of the Ar atoms depends str...Using a classical ensemble method, we have investigated sequential double ionization (SDI) of Ar atoms driven by elliptical laser pulses. The results show that the ion momentum distribution of the Ar atoms depends strongly on the pulse duration. As the pulse duration increases, the ion momentum distribution changes from two bands to four bands and then to six bands and finally to an eight-band structure. Back analysis of double ionization trajectories shows that the variation of the band structure originates from pulse duration dependent multiple ionization bursts of the second electron. Our calculations indicate that the subcycle electron emission in the SDI could be more easily accessed by using elliptical laser pulses with a longer wavelength. Moreover, we show that there is good correspondence between the scaled radial momentum and the ionization time.展开更多
Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme. The passage is formed with two parallel panels, one is rigid and the o...Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme. The passage is formed with two parallel panels, one is rigid and the other is flexible. The interaction between fluid flows and flexible panel is numerically studied, mainly focused on the effect of dynamic pressure and distance between two parallel panels. Subcycling and spline interpolation based predict-correct scheme is utilized to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate results. It’s demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels. Via analyzing the propagation and reflection of disturbance in passage, it’s determined as a main cause of the variations.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074239 and 91850209)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2020A1515010927 and 2020ST084)+3 种基金Department of Education of Guangdong Province,China(Grant Nos.2019KTSCX038 and 2020KCXTD012)Shantou University(Grant No.NTF18030)the Natural Science basic Research Program of Shaanxi Province,China(Grant No.2022JM-015)Scientific Research Foundation of SUST(Grant No.2017BJ-30).
文摘Subcycle spectral structures and dynamics of high-order harmonic generation(HHG)processes of atoms and molecules driven by intense laser fields on the attosecond time scale have been originally studied theoretically and ex-perimentally.However,the time scale of HHG dynamics in crystals is in the order of sub-femtosecond,and the carrier dynamics of HHG in crystals driven by subcycle laser pulses are largely unexplored.Here we perform a theoretical study of subcycle structures,spectra,and dynamics of HHG of crystals in mid-infrared laser fields subject to excitation by a subcycle laser pulse with a time delay.The HHG spectra as a function of time delay between two laser fields are cal-culated by using a single-band model for the intra-band carrier dynamics in crystal momentum space and by solving the time-dependent Schr?dinger equation in velocity gauge for the treatment of multi-band crystal systems.The results exhibit a complex time-delay-dependent oscillatory pattern,and the enhancement and suppression of the HHG related to subcycle pulse are observed at the given time delay in either single-band or multi-band crystal systems.To understand oscillation structures with respect to the dependence for the subcycle laser fields,the time-frequency characteristics of the HHG as well as the probability density distribution of the radiation are analyzed in detail.
基金supported by the National Natural Science Foundation of China(grant nos.92150105,12227807,12241407,11925405,and 12274294)the Science and Technology Commission of Shanghai Municipality(grant nos.21ZR1420100 and 23JC1402000).
文摘Exploiting the infinite-order continuous dynamical rotational symmetry of circularly or elliptically polarized classical light pulses,we establish the conservation law between the angular momentum and energy in strong-field ionization that is applicable at the subcycle level.We illustrate the conservation law through the correlated spectrum of angular momentum and energy of photoelectrons,both at the tunnel exit and in the asymptotic region.Moreover,we propose a protocol based on electron vortices to directly visualize the existence of the subcycle conservation law.Our work paves the pathway toward a deeper understanding of fundamental light-matter interactions on the subcycle scale.
基金supported by the National Natural Science Foundation of China (Grant No. 12074329)Nanhu Scholars Program for Young Scholars of Xinyang Normal University。
文摘With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our results show that the recollision time window can be precisely controlled within an isolated time interval of several hundred attoseconds, which is useful for understanding the subcycle correlated electron dynamics. More interestingly, the correlated electron momentum distribution (CEMD) exhibits a strong dependence on laser intensity. That is, at lower laser intensity, CEMD is located in the first quadrant. As the laser intensity increases,CEMD shifts almost completely to the second and fourth quadrants, and then gradually to the third quadrant.The underlying physics governing the CEMD's dependence on laser intensity is explained.
文摘Using a classical ensemble method, we have investigated sequential double ionization (SDI) of Ar atoms driven by elliptical laser pulses. The results show that the ion momentum distribution of the Ar atoms depends strongly on the pulse duration. As the pulse duration increases, the ion momentum distribution changes from two bands to four bands and then to six bands and finally to an eight-band structure. Back analysis of double ionization trajectories shows that the variation of the band structure originates from pulse duration dependent multiple ionization bursts of the second electron. Our calculations indicate that the subcycle electron emission in the SDI could be more easily accessed by using elliptical laser pulses with a longer wavelength. Moreover, we show that there is good correspondence between the scaled radial momentum and the ionization time.
文摘Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme. The passage is formed with two parallel panels, one is rigid and the other is flexible. The interaction between fluid flows and flexible panel is numerically studied, mainly focused on the effect of dynamic pressure and distance between two parallel panels. Subcycling and spline interpolation based predict-correct scheme is utilized to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate results. It’s demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels. Via analyzing the propagation and reflection of disturbance in passage, it’s determined as a main cause of the variations.
