Ionization in intense laser fields beyond the electric dipole approximation: concepts, methods, achievements and future directions

Abstract The electric dipole approximation is widely used in atomic, molecular and optical physics typically related to a regime for which the wavelength much larger than atomic structure. However, studies have shown that strong laser fields another exists where breaks down. During ionization process intense at long wavelengths photoelectrons can reach higher velocities such magnetic field component of becomes significant. dynamics final momentum electron therefore modified by entire Lorentz force. In contrast interaction neglected approximation. Rapid developments technology advancements accuracy measurements techniques enabled observation influence non-dipole effects on angular photoelectron distributions. More recently number beyond has increased significantly, providing more important insight into fundamental properties processes. For example we three dimensional spectra significantly affected drift with parent–ion interaction, linear multiphoton transfer sub-cycle time scale sharing transferred photon momenta between ion. this article present an overview underlying mechanisms review experimental achievements field. We focus not valid but fully relativistic description required.