Investigation of the reorientation of the liquid crystal molecules under the influence of the dye torque

Reorieantational mechanisms of the azo and anthraquinone dyes doped Liquid Crystal (LC) cells were investigated via pump-probe measurement setup. The change in the probe laser beam intensity values was observed before and after the pump laser is operated. A model approach was proposed to explain the probe beam intensity change and to predict the behavior of the LC molecules under the influence of dye torque. The model approach showed that the significant contribution to the intensity change of the probe beam comes from the reorientation of the LC molecules in the plane perpendicular to the cell walls. With the same model approach, the initial alignment angles of the molecules were predicted before the pump laser is operated.