Novel diffractive optics for mode division multiplexing of optical vortices

We present the design, fabrication and optical characterization of compact phase-only diffractive optical elements (DOE) for the (de)multiplexing of beams carrying orbital angular momentum (OAM) of light, engineered for integration into next-generation OAM-based optical platforms. Samples have been fabricated with high-resolution electron-beam lithography on polymethylmethacrylate (PMMA) resist layer spun over a glass substrate and the high quality has been inspected with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Various designs are presented for the sorting of optical vortices differing in either OAM content or beam size, with several steering geometries in far-field. The optical characterization has been performed at the selected wavelength ?=632.8 nm in terms of channel efficiency and inter-channel cross-talk, exhibiting remarkable optical performance.