Tunable photonic spin Hall effect and in-plane spin separation with PT-symmetric 1D multilayer structure with liquid crystal defect layer

We theoretically investigate tunable photonic spin Hall effect and in-plane spin splitting of light employing a parity time (PT)-symmetric 1D multilayer structure consisting of dielectric layers and liquid crystal as a defect layer. With generalized beam propagation method, the spatial separations between opposite spin states (LCP and RCP) in vertical and horizontal directions are examined with varying loss/gain and molecular orientations of liquid crystal. The exceptional points and non-Hermitian optical properties of the proposed 1D structure are studied using scattering and transfer matrix methods. In addition, we report enhancement, suppression and directional switching of vertical as well as horizontal spatial separations with the variation of loss/gain and the molecule orientation for both forward and backward incidences. The molecular orientation of the liquid crystal and the reflection coefficients reveal spatial separation of LCP and RCP components of the incoming light. The active manipulation of photonic spin states in vertical and horizontal directions unfolds potential applications in optical metrology, quantum information, spintronics, and non-reciprocal devices etc.