All-fiber generation and Poincaré sphere representation of double superposition states of OAM modes

This paper proposes a hybrid-order orbital angular momentum Poincaré sphere to refine the representation of high-order spatial modes. The orbital angular momentum Poincaré sphere is extended to a more general form. Benefiting from the degenerate case of the hybrid-order Poincaré sphere, this new Poincaré sphere is both complete and intuitive, enabling the guided generation of vector light fields. By utilizing an all-fiber structured light field generation system based on cascaded fused-biconical tapered mode selective couplers, some typical beams corresponding to arbitrary points on the hybrid-order orbital angular momentum Poincaré sphere are generated. This miniaturized solution for structured light field generation is both cheap and fast compared to liquid crystal devices.