Light controlled phase shifter for optofluidics.

We report the light-induced control of optical phase shift by a liquid crystal cell made with LiNbO3:Fe crystals as substrates. We show that a phase shift of a few πs can be easily reached for two orthogonal polarizations due to liquid crystal reorientation driven by the photovoltaic electric field originated in the substrates. This effect is exploited to get all-optical switching with a contrast of about 80%, by 2 s pump pulse.