Diffractive optics for combined spatial- and mode- division demultiplexing of optical vortices: design, fabrication and optical characterization

• DOI: 10.1038/srep24760
• Publication Date: 2016-04-20T09:22:30Z
• Authors: Gianluca Ruffato; Michele Massari; Filippo Romanato
• Keywords: Spatial light modulator; Optical vortex

During the last decade, orbital angular momentum (OAM) of light has attracted growing interest as a new degree freedom for signal channel multiplexing in order to increase information transmission capacity today's optical networks. Here we present design, fabrication and characterization phase-only diffractive elements (DOE) performing mode-division (de)multiplexing (MDM) spatial-division (SDM) at same time. Samples have been fabricated with high-resolution electron-beam lithography patterning polymethylmethacrylate (PMMA) resist layer spun over glass substrate. Different DOE designs are presented sorting vortices differing either OAM content or beam size regime, different steering geometries far-field. These novel appear promising telecom applications both free-space multi-core fibers propagation.