Effect of polymer concentration and localization on the electro-optical performance of cholesteric flexoelectro-optical devices

摘要

We discussed the effect of polymer concentration and localization on flexoelectro-optical device using short pitchcholesterics oriented in uniform lying helix texture. By using a small concentration of photoreactive liquid crystalmonomer with various concentrations and selecting the illumination conditions, we have been able to create a localizedpolymeric network at both substrate surfaces. We can stabilized the two switching modes and eliminating at the sametime the effect of the residual birefringence of the polymeric network in the field-unwound state of the sample. Thedevice has two operating modes: amplitude and phase modulation mode, respectively. The amplitude modulation modeis a fast in-plane switching of the device optic axis that enables to achieve a 100 % modulation of the transmitted lightintensity whereas the phase mode gives a continuous change of the refractive index and thus of the phase shift of thetransmitted light.