Collective Rotation of Molecules Driven by the Angular Momentum of Light in a Nematic Film

Abstract

It is experimentally demonstrated that a circularly polarized laser beam normally incident on a homeotropically aligned nematic film can induce a collective precession of the molecules in the film if the laser intensity is above the threshold for the Fr\'eedericksz transition. The effect is shown to result from a transfer of angular momentum from the laser beam to the medium.