Interferometric method for determining the sum of the flexoelectric

The time dependent periodic distortion profile in a nematic liquid crystal phase grating has been measured from the displacement of tilt fringes in a Mach-Zehnder interferometer. A 0.2 Hz squarewave voltage was applied to alternate stripe electrodes in an interdigitated electrode geometry. The time-dependent distortion profile is asymmetric with respect to the polarity of the applied voltage and decays with time during each half period due to ionic shielding. This asymmetry in the response allows the determination of the sum of the flexoelectric coefficients (e1 + e3) using nematic continuum theory since the device geometry does not possess inherent asymmetry. This is the accepted copy of the paper that was subsequently published as: “Interferometric method for determining the sum of the flexoelectric coefficients (e1 + e3) in an ionic nematic material” C.Trabi, C.V. Brown, A.A.T. Smith and N.J. Mottram Applied Physics Letters Vol. 92, 223509 (2008)