Linear and nonlinear photonic spin Hall effect induced by analog circular birefringence of Bessel-like beams

The spin Hall effect of a light beam is essentially a product of circular birefringence but is rarely demonstrated.Here,we provide a scheme for initiating off-axis circular birefringence based on the spin-dependent wave vector bifurcation of Bessel beams via a single liquid crystal Pancharatnam-Berry phase element.The tilted Bessel beam shows a detectable photonic spin Hall effect.By introducing the nonlinear propagation trajectories,the spin Hall effect is greatly enhanced.More surprisingly,the two spin states exactly propagate along the scaled trajectories,enabling flexible control of the spin separation.This phenomenon is also applicable to other Bessel-like beams with nonlinear trajectories,which have been already reported.