Semiclassical investigation of Coulomb focusing effects in atomic above-threshold ionization with elliptically polarized laser fields

We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach. With increasing laser intensity, the Coulomb focusing (CF) effects are found to become stronger in both parallel and perpendicular directions with respect to the polarization plane. The dependence of CF effects on tunnel exit, initial transverse momentum distribution and laser electric field is analyzed. It was revealed that the effects of tunnel exit are most prominent with variation of the laser intensity, and the other two factors both play non-negligible roles. Our results provide a deeper insight to the recent experiments of Coulomb asymmetry Shafir D, et al., 2013 Phys. Rev. Lett. 111 023005 and Li M, et al., 2013 Phys. Rev. Lett. 111 023006.