Topological steering of light by nematic vortices and analogy to cosmic strings

Liquid crystals are widely known for their technological uses in displays, electro-optics, photonics and nonlinear optics, but these applications typically rely on defining and switching non-topological spatial patterns of the optical axis. Here, we demonstrate how a liquid crystal's optical axis patterns with singular vortex lines can robustly steer beams of light. External stimuli, including an electric field and light itself, allow us to reconfigure these unusual light-matter interactions. Periodic arrays of vortices obtained by photo-patterning enable the vortex-mediated fission of optical solitons, yielding their lightning-like propagation patterns. Predesigned patterns and spatial trajectories of vortex lines in high-birefringence liquid crystals can steer light into closed loops or even knots. Our vortex lattices might find technological uses in beam steering, telecommunications, virtual reality implementations and anticounterfeiting, as well as possibly offering a model system for probing the interaction of light with defects, including the theoretically predicted, imagination-capturing light-steering action of cosmic strings, elusive defects in cosmology.

Automated summary

Liquid crystals can robustly steer beams of light with optical axis patterns of singular vortex lines, which can be reconfigured by external stimuli. The periodic arrays of vortices obtained by photo-patterning enable vortex-mediated fission of optical solitons, resulting in lightning-like propagation patterns. Pre-designed patterns and spatial trajectories of vortex lines in high-birefringence liquid crystals can steer light into closed loops or even knots. Liquid crystals with vortex lattices have potential applications in beam steering, telecommunications, virtual reality, and anticounterfeiting, as well as providing a model system for studying light-defect interactions including the light-steering action of cosmic strings.