On-off intermittency in stochastically driven electrohydrodynamic convection in nematics

We report on-off intermittency in electroconvection of nematic liquid cryst als driven by a dichotomous stochastic electric voltage. With increasing vo ltage amplitude we observe laminar phases of undistorted director state int errupted by shorter bursts of spatially regular stripes. Near a critical va lue of the amplitude the distribution of the duration of laminar phases is governed over several decades by a power law with exponent -3/2. The experi mental findings agree with simulations of the linearized electrohydrodynami c equations near the sample stability threshold.