Broadband decoupled spin and orbital angular momentum detection via programming dual-twist reactive mesogens

The introduction of spin and orbital angular momentum mode division multiplexing to existing wavelength division multiplexing will significantly enlarge the capacity of optical networks. Therefore, components compatible with the above techniques are in high demand. Here, a geometric phase combined a Dammann vortex grating, and a polarization grating is designed and encoded to a dual-twist reactive mesogen. It can generate a couple of vortex channel arrays highly efficiently in broadband. Meanwhile, orthogonal spins are spatially separated, facilitating spin identification. A vortex will recover to a Gaussian beam when it is diffracted to an order with opposite topological charge, which enables the detection of orbital angular momentum. It supplies a parallel and efficient way for decoupled spin and orbital angular momentum detection operating at the entire visible range, and the design may be extended to many other compatible optical communication components.