The manipulation of asymmetric spin splitting near the critical angle

The optical spin splitting has been extensively studied due to potential applications in precise metrology and nanophotonic devices. Thus, the enhancement and control of the optical spin splitting have always been the focus of many efforts. However, the manipulation of asymmetric spin splitting remains insufficiently explored near the critical angle. This work systematically investigates and experimentally demonstrates the manipulation of asymmetric spin splitting when arbitrary linearly polarized light is reflected near the critical angle. The results show that significant asymmetric spatial and angular spin splitting can be achieved near the critical angle by modulating the incident angle and polarization angle to affect the spin-dependent and independent terms, which are determined by the angular gradient and phase of reflection coefficients. Meanwhile, we demonstrate the manipulation of asymmetric spin splitting by observing the distributions of light field intensity and spin polarization state, and quantitatively characterize the manipulation of spatial and angular asymmetric shifts combined with the quantum weak measurement technique. This work provides new ideas for spin-photonic manipulation and is expected to promote the development of spin-photonic applications.