Liquid-crystal-based topological photonics

Liquid crystals are complex fluids that allow exquisite control of light propagation thanks to their orientational order and optical anisotropy. Inspired by recent advances in liquid-crystal photo-patterning technology, we propose a soft-matter platform for assembling topological photonic materials that holds promise for protected unidirectional waveguides, sensors, and lasers. Crucial to our approach is to use spatial variations in the orientation of the nematic liquid-crystal molecules to emulate the time modulations needed in a so-called Floquet topological insulator. The varying orientation of the nematic director introduces a geometric phase that rotates the local optical axes. In conjunction with suitably designed structural properties, this geometric phase leads to the creation of topologically protected states of light. We propose and analyze in detail soft photonic realizations of two iconic topological systems: a Su-Schrieffer-Heeger chain and a Chern insulator. The use of soft building blocks potentially allows for reconfigurable systems that exploit the interplay between topological states of light and the underlying responsive medium.

Automated summary

Liquid crystals provide exquisite control of light propagation due to their orientational order and optical anisotropy. By utilizing spatial variations in the orientation of nematic liquid-crystal molecules and suitable structural properties, topologically protected states of light can be created. The soft photonic realizations of iconic topological systems offer potential for reconfigurable systems exploiting the interplay between topological states of light and the medium.