Tailoring the photon spin via light–matter interaction in liquid-crystal-based twisting structures

We demonstrate the photonic spin Hall effect in a system comprising designable liquid crystal materials. The photoalignment technique provides an effective approach to control the directors of the liquid crystal molecules. Twisting structures with different transverse distributions are conveniently introduced into the liquid crystal plates for tailoring the spin–orbit coupling process to present various photonic spin Hall effect phenomena. The light–matter interaction in the twisting mediums is described with a Schrodinger-like equation. The photonic spin Hall effect considered in the study is explained as the result of an effective magnetic field acting on a pseudospin. Moreover, owing to the designability of the liquid crystal system, it is a potential platform for Hamiltonian engineering. Several valuable multiple quantum systems are possible to be presented in classical analogies.