Dynamics of the optical Freedericksz transition

We investigate theoretically dynamical aspects of the optical Freedericksz transition in nematic liquid crystals. Specifically, we analyze (1) the existence and stability of a sequence of higher-order longitudinal modes past the Freedericksz transition, (2) effects due to transverse correlations of the molecular orientation, and (3) the effects of thermal noise on the stability of the spatial modes. Higher-order longitudinal modes are studied both in the weak-anisotropy limit, in which case the problem reduces at steady state to a sine-Gordon equation, and in the general case, using a combination of analytical and numerical methods. They can be excited by the influence of internal fluctuations. Transverse correlations are shown to lead to the existence of transverse inhomogeneities (kinks) of the direct-angle distribution that can appear even under plane-wave illumination.