Electrically tunable cholesteric liquid crystal lines defects

In the work, the pattern formation in a planar-oriented Cholesteric Liquid Crystals (CLC) was studied for various thicknesses to pitch (d/p) ratios under the influence of an electric field directed perpendicular to the plane of the cell. In addition, the features of the director's fields and defects lines were studied. Indeed, we present the splitting of dislocation cores into disclinations with a nonsingular core, the geometry of director patterns associated with dislocation bends. Experimentally, three planar cells with the gap thicknesses d corresponding to three Grandjean zones were prepared with d/p approximate to 1/2, 1, and 3/2. The results show that the dynamic pattern formation of the grating stripes was performed in a different manner. For d/p approximate to 1/2 and d/p approximate to 1, the stripes were showed through the whole cell surface parallel and perpendicular to the rubbing direction, respectively. As well, their contrast was increased with time during formation. In this case, the defect core structure split into a lambda- 1/2 lambda+1/2 pair disclinations for a burger vector (b) equal to the pitch (p) dislocation. Besides that, when d/p approximate to 3/2, the grating stripes were performed near the boundaries of the surfaces and then prolonged to the entire cell surface along the rubbing direction. Here, the defect core structure split into a r- 1/2 r+1/2 pair disclinations for a b = p dislocation.