  We show that the motion of ferroelectric liquid sessile droplets deposited on
a ferroelectric lithium niobate substrate can be controlled by a light beam of
moderate intensity irradiating the substrate at a distance of several droplet
diameters from the droplet itself. The ferroelectric liquid is a nematic liquid
crystal in which almost complete polar ordering of the molecular dipoles
generates an internal macroscopic polarization locally collinear to the mean
molecular long axis. Upon entering the ferroelectric phase droplets are either
attracted toward the center of the beam or repelled, depending on the side of
the lithium niobate exposed to light irradiation. Moreover, moving the beam
results in walking the ferroelectric droplet over long distances on the
substrate. We understand this behavior as due to the coupling between the
polarization of the ferroelectric droplet and the polarization photoinduced in
the irradiated region of the lithium niobate substrate. Indeed, the effect is
not observed in the conventional nematic phase, suggesting the crucial role of
the ferroelectric liquid crystal polarization.
