Optical spin-to-orbital angular momentum conversion in the near field of a highly nonparaxial optical field with hybrid states of polarization

The conversion of the spin-to-orbital optical angular momentum (AM) of an optical field with hybrid states of polarization (SOP) in the near-field region is studied based on the angular spectrum method. The spin-to-orbital optical AM conversion occurs in the longitudinal component of an optical field with hybrid SOP under a highly nonparaxial circumstance. The longitudinal component exhibits different phases and intensity distributions compared to that of the transverse component and it depends sensitively on the initial SOP. Our study reveals that the density distribution of the converted orbital AM can be spatially manipulated by controlling the initial state of polarization.