Optical properties of homeotropically aligned flexoelectric nematic layers deformed by direct current electric field

Optical properties of homeotropically aligned flexoelectric nematic layers deformed by dc electric fields were analyzed by calculating the phase difference Δφ between ordinary and extraordinary light rays passing through a layer placed between crossed polarizers. A phase difference arises when the bias voltage U exceeds the threshold value U_T. Close to the threshold, Δφ increases linearly with U. The possibility of using this effect to detect the flexoelectric properties of the nematic was explored by simulated experiments. The method considered in this paper is based on measurement of the slope of the linear section of the voltage dependence of Δφ, which depends on the sum of the flexoelectric coefficients and which differs from a well-known theoretical slope that ignores flexoelectric properties. The difference between the slopes reveals the flexoelectric properties of the nematic. The effectiveness of the proposed method is discussed.