  Inducing and controlling the ultrafast molecular rotational dynamics using
shaped laser fields is essential in numerous applications. Several approaches
exist that allow following the coherent molecular motion in real-time,
including Coulomb explosion-based techniques and recovering molecular
orientation from the angular distribution of high harmonics. We theoretically
consider a non-intrusive optical scheme for visualizing the rotational dynamics
in an anisotropic molecular gas. The proposed method allows determining the
instantaneous orientation of the principal optical axes of the gas. The method
is based on probing the sample using ultra-short circularly polarized laser
pulses and recording the transmission image through a vortex wave plate. We
consider two example excitations: molecular alignment induced by an intense
linearly polarized laser pulse and unidirectional molecular rotation induced by
a polarization-shaped pulse. The proposed optical method is promising for
visualizing the dynamics of complex symmetric- and asymmetric-top molecules.

Optics;Chemical Physics