Vortex decomposition and reconfiguration via transformation optics

The potential of optical orbital angular momentum (OAM) to create boundless dimensional Hilbert spaces has garnered considerable interest for augmenting the capacity of communication systems. Precise detection and reconfiguration of optical vortices (OVs) carrying distinct topological charges are crucial for leveraging their communicative potential. Here, based on transformation optics (TO), we theoretically propose a straightforward method for OV decomposition and reconfiguration. We first transform spiral vortices into planar waves with varying refraction angles and subsequently restore the vortices at designated image points with the aid of coherent perfect absorbers. Employing Hamiltonian optics, we analyze the trajectory of OV rays at both source and image positions, revealing an efficient reconfiguration of the OAM field that accounts for the phases of the sources. Our findings demonstrate flexible manipulation of OAM through TO, offering substantial advancements in communication technologies, including on-chip signal filtering and demultiplexing.