Ionization and high harmonic generation of two-dimensional quasiperiodic structures in arbitrarily polarized strong laser fields

Abstract

The ionization and high harmonic generation from two-dimensional quasiperiodic structures in strong laser fields are studied by numerically solving the time-dependent Schrodinger equation, in which a two-dimensional Kronig–Penney potential has been adopted to mimic the target. The two-dimensional photoelectron momentum distribution is significantly governed by the two-dimensional quasiperiodic potential, and thus is distinct from the single atom case. The low order harmonics initiated by a circularly polarized driving laser field are also circularly polarized and present alternative helicities; however, the high order harmonics deviate from circular polarization due to the unstable phase variation between different components. This calculation shows that elliptically polarized harmonics can be effectively generated by a circularly polarized driving laser field, and it sheds light on laser–surface interaction.