Controlling non-sequential double ionization with chirped laser pulse

Abstract

The non-sequential double ionization (NSDI) of He in a chirped few-cycle laser pulse is studied using a full-dimensional semi-classical model. The NSDI probability is found to be very sensitive to the rate of wavelength change. An abrupt jump is found in the probability distribution during the crossover from up- to down-chirped pulse, followed with a further increase of the probability when keep increasing the rate of wavelength change. In the meantime, the correlated electron momentum distribution transfers from anti-correlated to a correlated pattern. Further analysis reveals the underlying mechanism to be the increase of the kinetic energy of returned electron acquired from the chirped pulse in the re-collision process. The dominant NSDI mechanism transfers from recollision-induced excitation with subsequent field ionization (RESI) to electron-impact ionization (EI). Therefore, the chirped laser pulse could be a useful tool for controlling the electron dynamics in NSDI and beyond.