Electro-optic and opto-optic effects in liquid crystal waveguides

A guided light wave can be modulated by coupling it into a ferroelectric liquid crystal (FLC) waveguide. The FLC, which changes its optical properties under the application of an electric field, acts as active medium. With a carefully chosen aligned configuration, the large change in refractive index induced by the electric field, gives a good contrast ratio in the optical response. The optical and electro-optical properties of liquid crystals can be modified by the propagating light and these effects can be enhanced by the addition of a suitable absorbing dye in the liquid crystal. Thus changes in the guiding conditions of the light can be induced also by the guided light itself.