  Recent developments in the field of photonic spin Hall effect (SHE) offer new
opportunities for advantageous measurement of the optical parameters
(refractive index, thickness, etc.) of nanostructures and enable spin-based
photonics applications in the future. However, it remains a challenge to
develop a tunable photonic SHE with any desired spin-dependent splitting for
generation and manipulation of spin-polarized photons. Here, we demonstrate
experimentally a scheme to realize the photonic SHE tunably by tailoring the
space-variant Pancharatnam-Berry phase (PBP). It is shown that light beams
whose polarization with a tunable spatial inhomogeneity can contribute to
steering the space-variant PBP which creates a spin-dependent geometric phase
gradient, thereby possibly realizing a tunable photonic SHE with any desired
spin-dependent splitting. Our scheme provides a convenient method to manipulate
the spin photon. The results can be extrapolated to other physical system with
similar topological origins.
