An optical system, comprising: (i) multiple input optical fibers; (ii) an optical mode multiplexer/demultiplexer coupled to said input optical fibers with, said optical mode multiplexer/demultiplexer comprising a plurality of metamaterial structures having length and forming at least one stage of metamaterials, the at least one stage of metamaterials is being situated on a surface of the optical mode multiplexer/demultiplexer facing the input optical fibers, and the at least one stage of metamaterials is oriented at angles between 60 and 120 degrees relative to the axis of the input fibers; and the metasurfaces are structured to receive a first optical signal having a first mode from at least one of said multiple input optical fibers and convert the first mode to a different mode.