PROPERTIES OF HIGH-ORDER HARMONIC GENERATION SIGNALS FROM SWITCHED-OFF ALIGNED MOLECULES

A quantum theory of intense-field pump-probe experiments proposed recently, which successfully described the high-order harmonic generation (HHG) signals of adiabatic and non-adiabatic aligned molecules, is applied here to investigate the HHG signals from molecules aligned by using switched-off schema. The results are presented in the two externally available control parameters: the delay time, td, between the pump and the probe pulse, and the relative angle, α, between their polarizations. To provide more succinct and clearer information of the beats involved in the signal, the signal is also presented in the frequency domain. The results show that the HHG signals of switched-off aligned molecules mimic those of the adiabatic and non adiabatic aligned molecules, and therefore, it can be used to determine some molecular properties, as powerful as non-adiabatic signal. In addition, the HHG signals of switched-off aligned molecules also have benefit, which is it gives a greater modulation depth.