Reconfigurable topological defect arrays in nematic liquid crystals

Abstract

Topological defects in nematic liquid crystals (NLCs) are attracting attention in recent years for generating optical vortex beams. In most cases, complex defects structures are stabilized by pre-patterned surfaces and spontaneous control with reconfigurability is not so successfully realized. Here, we use NLCs with negative dielectric anisotropy doped with a small quantity of ionic impurity confined between perfluoropolymer surfaces. Without using a template, a large number of topological defects are stabilized by the reorientation of the NLCs using an AC voltage, which is caused by a periodic density modulation of ions at the perfluoropolymer interfaces. Due to the reconfigurable property of the system, the uniform monodomain can be obtained by several methods, for example, an infrared laser and a weak shear flow. Our results offer a new approach for stabilizing multiple topological defects.