Binary diffractive optics for 3D-demultiplexing of OAM beams

We propose to use a combination of spiral Fresnel zone plates (SFZPs) and binary diffractive gratings in order to realize 3D-demultiplexing of vortex beams – laser beams having an orbital angular momentum (OAM). It is known that binary and blazed fork-shaped diffractive gratings are widely used for demultiplexing of OAM beams and their analysis. In contrast to the fork-shaped gratings, in the case of SFZPs the diffraction orders differ in their focus positions along the propagation axis. A combination of these two approaches allows us to perform the socalled 3D-demultiplexing of OAM beams. (paper)