Abstract

Large optical nonlinearities from molecular reorientation are observed in freely suspended films of tilted layered smectic-C liquid crystals. Unlike the nematic case, smectic-C molecules are restricted to reorienting about the layer normal. The light interacts with the light-induced dipole, producing an optical torque on the molecules. Within the 100-molecular layer film, a region is reoriented, producing an elastic torque which balances the optical torque. As the linear light polarization angle is changed, the optical torque varies. Thermal effects are negligible, since the intensity is fixed. Above a threshold intensity, there are two stable configurations for the same polarization angle. The reorientation is found by measuring the phase shift of the central region with a weak probe beam. A simple torque-balance model explains all the observed behavior.

© 1988 Optical Society of America