Mass shift effect on relativistic high-order harmonic generation

Abstract

By solving the time-dependent Dirac and Schrödinger equations, we investigate the super high-order harmonic generation (HHG) from a one-dimensional model atom in a relativistic intense laser pulse. Our numerical simulations show that the relativistic results can be degraded to non-relativistic ones in the weak laser field, and the clear effect of the relativistic mass-shift can be gradually observed as the increase of the laser field intensity. Furthermore, the cutoff frequency and the emission efficiency of the HHG spectrum are analyzed by the wavelet time-frequency analysis and the relativistic "three-step" model.