Unwound chiral nematics as a playground for optical and topological solitons

Unwound chiral nematics controlled by confining surface anchoring and geometry are frustrated systems that exhibit a variety of metastable topological solitonic structures. On top of that, their intrinsic chirality reduces the laser power needed for the propagation of bouncing optical solitons, whereas nonlinear chiral nematic media periodically compensate for the diffraction spreading of light beams more effectively than in conventional nematicons. Unwound chiral nematics thus provide an excellent playground for studying the interactions of topological and optical solitons. Modeling and simulations first developed for linear light interaction are here extended to nonlinear situations experimentally studied by Smalyukh's group. The delicate balance of the light-to-matter transfer of momentum and the force due to the nonlocal orientational elasticity of chiral liquid crystals enables the tractor effect and spatial localization of topological solitons. These simple examples show that the optomechanical interplay of both kinds of solitons has potential for use in soft photonics.