Flexible manipulation of optical angular momentum using a spherical wavefront

Optical angular momentum (AM), comprising spin angular momentum (SAM) and orbital angular momentum (OAM), is crucial in various applications, yet its flexible control remains challenging.This study proposes, to our knowledge, a novel method for manipulating SAM and OAM using spherical wave illumination and the -shaped spiral aperture.By adjusting the spherical wave's convergence or divergence, the sign of SAM and OAM can be switched, while the geometric topological charge of the aperture transfers to the optical AM due to AM conservation.The method is theoretically analyzed, simulated, and experimentally validated, offering a compact platform applicable to photonic systems, particle manipulation, and encryption.