Investigation on molecular alignment induced by the few-cycle laser pulse and its phase evolution

Background: Molecular alignment and orientation are the hot topics in the ultrafast optics and the atomic, molecular and optical physics, since they are involved the laser field interaction with the atoms and the molecules. Objective and method: Here, we investigate the alignment of gaseous carbon monoxide induced by the strong few-cycle laser pulse based on the rigid rotor approximation theory. Results: The simulations show that there is a periodic recurrence in the alignment degree depending on the laser intensity, which is reduced by the dephasing-rephasing processes of molecules' rotation. The carrier-envelope phase of the few-cycle laser also affects the alignment of the molecules, and produces a phase evolution alignment. The underlying physical mechanisms are discussed. Significance: Our results might give a clue to understand the controlling the rotations of the gaseous molecules by the few-cycle laser pulse, and other revolved high-density physics processes.