Free space optical communications system with helical beams

We propose an experimental model of free space optical communicator in which the information is carried by different orbital angular momentum values. In this sense independent helical beams are superposed in the same channel of communication in order to increase the capacity of the transmitted information. The information is encoded with optical vortices generated by reflective spiral phase plates placed in a cascade configuration. The decoding consists in the reconstruction of initial Gaussian beams and it is performed with fork-like computer generated holograms.