Controlled wiring of disclination lines between patterned photoalignment layers in nematic liquid crystal

Abstract

On demand creation of topological defect configurations is a relevant topic for theoretical studies but also enables new developments in the field of photonics, stimuli-responsive actuators and colloidal assemblies. Liquid crystals (LCs) provide a versatile and technologically relevant material system to study topological defects, and photoalignment enables complex surface patterning that includes the formation of defects. This work is based on periodic defect grids of +1/2 and −1/2 defects, imposed at the top and bottom surface of a LC cell. The periods at the two substrates are slightly different and the azimuthal orientation of the defects is varied, so that different types of disclination interconnections are formed in the bulk of the LC. Some disclination lines connect defects at opposing substrates, while others connect defects on the same substrate. The experimentally generated configurations are simulated with the help of finite element Q-tensor simulations in order to get a detailed understanding of the defect formation. The optical appearance in polymerizing optical microscopy images is compared to optical simulations to verify the validity of the director configurations.