We unveil the physical origin of the peculiar spatio-temporal instability phenomena observed in liquid crystals subject to the influence of a light wave of ordinary polarization. Our study shows that due to non-adiabatic propagation of a light beam in an anisotropic medium, the Light polarization and, hence? the torque acting on the orientation of a nematic liquid crystal (NLC) is asymmetrically modulated over the NLC layer. The spatial pattern of the NLC reorientation that is formed across the NLC-layer under the influence of such a torque may become unstable in time due to competing interaction of symmetric and antisymmetric modes. The obtained results allow evaluation of the threshold intensity and the range of the light incidence angles where the longitudinal spatio-temporal instability is possible. (C) 1998 Elsevier Science B.V. All rights reserved.
Temporal instability due to competing spatial patterns in liquid crystals in the light field
CARBONE, Vincenzo;CIPPARRONE, Gabriella;Umeton C;VERSACE, Consolato Carlo;
1998-01-01
Abstract
We unveil the physical origin of the peculiar spatio-temporal instability phenomena observed in liquid crystals subject to the influence of a light wave of ordinary polarization. Our study shows that due to non-adiabatic propagation of a light beam in an anisotropic medium, the Light polarization and, hence? the torque acting on the orientation of a nematic liquid crystal (NLC) is asymmetrically modulated over the NLC layer. The spatial pattern of the NLC reorientation that is formed across the NLC-layer under the influence of such a torque may become unstable in time due to competing interaction of symmetric and antisymmetric modes. The obtained results allow evaluation of the threshold intensity and the range of the light incidence angles where the longitudinal spatio-temporal instability is possible. (C) 1998 Elsevier Science B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
