Laser-field-free molecular orientation with combined electrostatic and rapidly-turned-off laser fields

We propose a strategy to achieve laser-field-free molecular orientation with the combination of an electrostatic field and an intense, nonresonant laser field with rapid turn off. The adiabatically created pendular state is effectively transferred to the rotational wave packet in the nonadiabatic regime after the rapid turn off of the laser pulse and the orientation achieved at the peak of the laser pulse is revived at the rotational period of the molecule with the same degree of orientation. The remarkable difference in molecular behavior is found between alignment and orientation, which reveals the crucial importance of the sufficiently long rising time of the laser pulse to achieve the highest possible degree of orientation. The feasibility has been examined for OCS molecules as a sample under practical experimental conditions.