Optical control of isothermal phase transitions in nematic liquid crystals: strong excitation regime

Circular and helicoidal standing electromagnetic field induced isothermal phase transitions are observed and studied in nematic liquid crystals. Significant deviations from the case of traveling wave induced transitions are experimentally detected as far as the dynamic and hysteresis character of the transition are concerned. Optical control, e.g., formation of molecular reorientation stable and asymmetric deformation modes in circularly symmetric light fields, is achieved in the strong excitation regime. Particular self-modulation of (1) the azimuthal symmetry of light-matter interaction and of (2) the angular momentum of excitation beams is responsible for the observed behavior. (C) 1998 Elsevier Science B.V.