Contribution of multiple electron rescatterings on high-order harmonic generation in the mid-infrared wavelength regime

We theoretically investigate multiple electron rescatterings in high-order harmonic generation with a wide range of driving laser wavelengths. In order to obtain a clear and intuitive insight, the time-frequency analysis of the dipole acceleration calculated by the numerical solution of the time-dependent Schr?dinger equation is performed and compared with the classical electron trajectory calculation. The result shows that in the mid-infrared regime, the high-order electron trajectory associated with multiple rescatterings plays a more important role than the usually referred-to 'long and 'short' electron trajectories. To provide quantitative evidence, the strong-field approximation is used to calculate the yield ratio of the high-order harmonic generation from the first rescattering and the multiple rescatterings.更多还原