Direct and reciprocal spin-orbit interaction effects in a graded-index medium

Spin-orbit interactions (SOI) arising due to the propagation of a paraxial light beam, with spin-angular momentum and intrinsic- and extrinsic-orbital angular momentum degrees of freedom, along a curved trajectory and their mutual interactions is investigated due to several fundamental effects of interest. We demonstrate here all six direct and reciprocal SOI effects due to the propagation of light in an inhomogeneous-anisotropic medium, such as a graded-index rod. We show that each of light’s angular momentum component impacts the other in such a way as to have a unique effect, characterized using interferometry, polarimetry, and weak measurement methods. The results are expected to have significant impact on the basic understanding of light-matter interaction and its applications.