A fast linear electro-optical effect in a non-chiral bent-core liquid crystal

Abstract

We report on the observation of an electro-optical effect for a linear rotation of the optical axis as a function of the electric field in an achiral tilted bent-core liquid crystalline compound, in which the 4-cyanoresorcinol bisbenzoate core is symmetrically terminated by long linear alkyl chains (n = 16) on both ends. The linear electro-optical effect observed in this material is similar to the deformed helical ferroelectric liquid crystal (DHFLC) effect reported previously in a FLC material except that dimensions of the helical pitch differ by two orders of magnitude. In a chiral system, the helical pitch usually lies on the scale of sub-optical wavelength, ∼0.3 μm, depending on the material and the temperature, whereas in an achiral system, the pitch lies on the nm scale. The DHFLC mode shows fast, analog switching due to a gradual distortion of the uniform helical structure by the electric field; the switching speed is faster than that for the chiral system. In contrast to the chiral FLCs, achiral liquid crystalline materials appear to be better candidates for applications in displays and photonic technologies.