Theoretical Study On Photoelectron Interference Effect Of Hydrogen Atom In Intense Laser Pulses

As a high-intensity coherent light source,"laser" has greatly accelerated the growth of optics.People have been committed to using innovative methods to obtain shorter and faster laser pulse from the initial invention of the laser to the present ultrafast laser pulse.When exploring the interaction between the ultrafast laser pulse and the matter,the response of molecules,atoms and electrons to the laser pulse is the focus of attention.In the process of the interaction between intense laser pulse and matter,we can observe the non-sequential double ionization,photoelectron vortex and photoelectron holographic interference etc.For different phenomena,there have different ionization mechanism and dynamics of the electrons.For example,according to the non-sequential double ionization of the electrons,the correlation effect between electrons can be well explored;according to the photoelectron holographic interference structure,molecular imaging can be carried out,etc.In this paper,we illustrate the photoionization effect of the hydrogen atom under intense laser pulse,the main contents and results are as follows:We investigate the change of the photoelectron interference structure of the hydrogen atom driven by a linearly polarized pulse.Firstly,we change the laser wavelength.We can observe that there is a clear temporal double-slit interference structure in relatively high energy region at long wavelength,which is not observed at short wavelength.Combining the effect of Coulomb potential on electrons and the source of the temporal double-slit interference structure,we find that the focusing effect of Coulomb potential becomes weaker and the number of directly ionized electrons increase with the increase of the wavelength.The time-domain double-slit interference structure can be observed in relatively high energy region of the photoelectron momentum distribution.Then,we analyze the influence of Coulomb potential on the photoelectron momentum distribution of the hydrogen atom in detail.We divide an optical period into different ionization time windows,we find that the combination of different time windows corresponds to different photoelectron interference structures in different regions.Through the trajectory analysis,we illustrate the influence of Coulomb potential on the interference structure.The precise control of the ionization channel is achieved by adjusting the appropriate chirp parameters under the driving of a few cycle chirped laser pulse,and the photoelectron holography interference structure is also isolated.By using the quantum method and the semi-classical two-step model,when the carrier envelope phase is fixed,we find that the photoelectron momentum distribution is more sensitive to the negative chirped laser pulse than that to the positive chirped pulse.Under the action of a negative chirped laser pulse,the isolated holographic interference structure with ionization time on the attosecond time scale can be isolated from the photoelectron momentum distribution by adjusting the appropriate negative chirped parameters.In addition,we also prove that the chirped laser pulse can not only precisely control the ionization channel,but also can be used to control the rescattering process.Through the trajectory analysis,the results show that under the driving of the negative chirped laser pulse,with the increase of the negative chirp parameter,the drift time of the rescattering electrons increases,and the movement time of the electrons in the field becomes longer,and the electron can obtain the high energy from the field.In addition,when the chirp parameter is fixed,the photoelectron momentum distribution is also very sensitive to the carrier envelope phase of a few-cycle laser field.The dependence of the photoelectron interference structure on the wavelength in a spatially inhomogeneous field is investigated by using the improved quantum trajectory Monte Carlo method(ISCTS).The research of the photoelectron momentum distribution in spatially inhomogeneous field is still very few.In order to better understand the influence of spatially inhomogeneous field on the electrons,we investigate the photoelectron momentum distribution in spatially homogeneous field and spatially inhomogeneous field,respectively.We find that the electron is more sensitive to the wavelength dependence in the spatially inhomogeneous field.With the increase of wavelength to a fixed value,the photoelectron momentum distribution is exactly separated into two parts,that is,the relatively high energy region and the relatively low energy region.We call the wavelength is the critical wavelength.For the long wavelength,the rescattering electrons return to the parent nucleus with high energy.At the same time,we also illustrate that the photoelectron holographic interference structure can be isolated in spatially inhomogeneous field.Moreover,the holographic interference structure can be observed more clearly in the short wavelength than in the long wavelength.Finally,we prove that the critical wavelength is different for the different inhomogeneity parameters.