Localized soft mode at optical-field-induced Freedericksz transition in a nematic liquid crystal

Collective orientational fluctuations near optical-held-induced Freedericks z transition in a homeotropically aligned nematic Liquid crystal 5CB are st udied by dynamic light scattering. A softening of the orientational fluctua tion mode corresponding to the transverse profile of the optical field was detected. The observed properties of the soft mode are described by a singl e localized bound mode of the orientational fluctuations in an effective po tential well formed by the optical held. The results of the model agree wit h the experiment without any adjustable parameter.