Influence of ions on the "V-shaped" electro-optic response of ferroelectric liquid crystals - art. no. 031703

It has recently been shown that in surface-stabilized ferroelectric liquid crystal cells with high spontaneous polarization, the polarization charge s elf-interaction leads to a "V-shaped" optical response to an applied voltag e. The presence of ionic fi ee charges in the liquid crystal changes the in ternal electric field. and therefore also the spatial dependence of the pol arization and optic axis orientation. We have numerically solved the nonlin ear ion diffusion equation in the electric field due to external voltage, s pontaneous polarization, and ions, and calculated the electro-optic respons e to a triangular applied voltage. When the period of the driving voltage i s smaller than the zero-field diffusion time of the ions across the cell, a nd larger than the ion transit time in the applied field, an inverse hyster esis in the electro-optic response is obtained. At these time scales ions a lso cause characteristic changes in the shape of the electro-optic response .