Energy exchange in ultrafast dynamics of atom with strong laser fields

Abstract

Using the three-dimensional classical ensemble model, we investigate the dependence of the energy absorbed by two electrons (Ar atom as an example) from the laser field on the laser parameters (wavelength, laser intensity and ellipticity). The results show that when the laser intensity is fixed and the wavelength increases, the energy absorbed by the two electrons from the laser field increases as a whole, but the trend is slightly different under different intensities. At lower intensity the dependence of the energy absorbed by the two electrons from the laser field on wavelength increases steadily and at higher intensity it decreases slowly and then increases rapidly. The intensity dependence of the energy absorbed by two electrons from the laser field in the whole ensemble presents two interesting intersections at different wavelengths. The dependence of the energy absorbed by the two electrons from the laser field on the ellipticity first decreases and then increases slowly at lower intensity; it has a “Ladder shape” that slowly increases and then decreases and finally slowly increases at moderate intensity; it shows a trend of increasing first and then decreasing at higher intensities. In order to explain the dependence of the energy absorbed by two electrons from the laser field on the laser parameters (wavelength, laser intensity and ellipticity), the kinetic process of the whole ensemble is divided into four channels: double ionization, single ionization, frustrated single ionization and frustrated double ionization. The characteristics of each channel and how it dominates the overall trend of energy absorption from the laser field by the two electrons are then analyzed. The analysis results show that the dependence of the energy absorbed by the two electrons from the laser field on wavelength、laser intensity and ellipticity is due to the fact that some channels dominate the energy absorbed by the two electrons from the laser field.