Solitonlike dynamics in submicron ferroelectric liquid-crystal cells

Using a linear electro-optic response technique we have determined the phase mode dynamics of a chiral ferroelectric smectic-C* liquid crystal confined in a wedge-type cell. Below the smectic-A--smectic-C* phase transition we have observed two polar phase modes. The relaxation rate of the higher-frequency mode scales as the inverse square of the cell thickness and is identified as a transverse solitary wave in the splayed ferroelectric structure. The relaxation rate of the slow mode is on the other hand nearly thickness independent. By increasing measuring voltage, this mode shows a nonlinear crossover to the collective switching of the polarization of the cell as a whole. The observed dynamics is described within the Landau-Khalatnikov theory, where the polarization renormalized dynamics and the effects of confinement are taken into account.