Fast integrated electro-optical switch and beam deflector based on nematic liquid crystal waveguides

In this paper, the design, the realisation and the experimental characterisation of an integrated electro- optical switch and a beam deflector, both based on a planar nematic liquid crystal (NLC) waveguides, are reported. In order to test such a devices, particular waveguide structure consisting of a three-stage device, having a thin nematic LC film as middle stage and two glass waveguides as other stages, has been designed and realised. The electro-optical behaviour and the response time have been studied for different configurations for both TE and TM polarised light. By a proper choice of the material parameters and due to the presence of an additional constant bias voltage, we got response time in the microsecond range. The experimental results obtained are very promising in the frame of integrated electro-optical devices, even if the effect underlying the results is not yet understood and probably need some deep insight into liquid crystal physics and into surface interactions.