High data-transfer density using 4-states optical vortices for deep space optical communication links

Free space optical communications greatly benefit from radiation carrying orbital angular momentum because of the large number of topological charges that can be used to encode information at high density. In this work, we show how to realize an optical link by exploiting four mutually incoherent beams carrying different orbital angular momentum states. The four related channels are digitally modulated using On-Off keying techniques. The receiver is based on a local interferometer that allows recovering of the original information, with high efficiency, by exploiting only a small portion of the radiation wavefront. This technique can be applied for high data-transfer density in satellite network communications, when the radiation wavefront exceed the receiver size.