Intensity-dependent asymmetric photoionization in few-cycle laser pulses

The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.

National Natural Science Foundation of China [60408008, 10774153]; Natural Science Key Foundation of Shanghai [04JC14036]; National Basic Research Program of China [2006CD806000]; Rising Star Program of Shanghai, China [08QH1402400]