Light Leakage Induced by Spontaneous Distortion of the Nematic Director in Bulk Defect Structures

Abstract

Three director profiles of nematic liquid crystal (NLC) cells are presented to elucidate the mechanism of light leakage induced by some defects hidden in NLC cells. In accordance with Landau-de Gennes theory, we simulated the dynamics of these defect profiles using the 2-D finite-difference iterative method and calculated their transmittance using the Jones calculus. Results show that light leakage induced by these defects is caused by spontaneous azimuthal twisting of the director when no electric field is applied. Spontaneous distortion occurs only in the director field around defects and depends on larger nematic anisotropies. The light leakage intensity in cells I and II differs because of difference in the defect structures of the cells. Regardless of the cell type, light leakage is exacerbated when the surface anchoring strength is nonuniform. Light leakage disappears at a critical value of electric field $E_{c}$ . However, a very strong static electric field $E_{c}^{\ast}$ is necessary to force the light leakage to disappear when the flexoelectric effect is considered.