The optical spin Hall effect has been extensively observed in various spatially structured beams. In this work we actively break the rotational symmetry of a radially polarized beam carrying an optical vortex through the off-axis phase singularity, thereby systematically investigating the induced optical spin Hall effect. We propose and generate radially polarized beams carrying an off-axis optical vortex, termed radially polarized off-axis vortex beams (RPOffVBs), and study their evolutions of both state of polarization and spin angular momentum (SAM) during the focusing process. By changing the off-axis distance of the phase singularity and/or the position of the relative focus, it is shown that the SAM density distribution of the RPOffVB can be controlled, while their total SAMs remain conserved. Moreover, it is observed that the transverse separation phenomenon of the SAM density distribution in the focal field region, where the separation of left-handed and right-handed circular polarization components—caused by their difference in Bessel function orders—results in asymmetric local SAM density distribution and the emergence of the optical spin Hall effect. This study provides insights into the SAM characteristics of focused off-axis vortex beams with radial polarization and contributes to the development of advanced optical manipulation and polarization imaging technologies.

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• Angular momentum of light
• Lenses
• Polarization