Flexoelectric polarisation effects in nematic liquid crystal phase gratings

C.L. Trabi, A.A.T. Smith, N.J. Mottram, C.V. Brown

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Nematic phase gratings have been studied in which a planar nematic layer of thickness 17.2 μm is sandwiched between two glass substrates coated with an alignment polymer. The upper substrate is a continuous earth plane and the lower substrate has a patterned electrode of interdigitated stripes (electrodes and gaps are both 40 μm wide). Reorientation of the nematic liquid crystal occurs in response to d.c. electric fields applied between the interdigitated electrodes. These nematic reorientation regions have been used to investigate the influence of the flexoelectric polarisation in the nematic liquid crystal by observing the resultant (i) movement of tilt fringes in a Mach-Zehnder interferometer, and (ii) optical diffraction patterns. In the Mach-Zehnder interferometer the periodic variation of the refractive index resulting from the periodic distortion profile is measured directly from the displacement of the tilt fringes. The asymmetry in the response to positive and negative polarities of the d.c. voltage for both measurement techniques is directly related to the sum of the flexoelectric coefficients, e1 + e3.
Original languageEnglish
Publication statusPublished - 2008
EventConference on Liquid Crystals XII - San Diego, CA
Duration: 11 Aug 200812 Aug 2008


ConferenceConference on Liquid Crystals XII
CitySan Diego, CA


  • flexoelectric polarisation
  • flexoelectric polarization
  • nematic phase gratings
  • liquid crystal
  • Mach-Zehnder interferometer
  • diffractive optical element


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