Three-dimensional imaging of liquid crystal structures and defects by means of holographic manipulation of colloidal nanowires with faceted sidewalls

We use nanowires with faceted sidewalls for mapping of the patterns of three-dimensional orientational order and defect structures. In chiral nematics, the nanowires follow the local average orientation of rod-shaped molecules. When spatially translated by use of holographic optical tweezers in three dimensions, they mediate direct nondestructive visualization of the helicoidal ground-state structures, edge and screw dislocations, and kinks, as well as enable non-contact manipulation of these defects. We probe interactions of faceted nanowires with different defects and demonstrate their spontaneous self-alignment along the cores of singular defect lines.