Demonstration of free-space one-to-many multicasting link from orbital angular momentum encoding

Multicasting is necessary when distributing signals between multiple users. In this Letter, we demonstrate an orbital angular momentum (OAM) encoding-based free-space one-to-many multicasting link, where digital signals are encoded into a series of time-varying OAM states and transmitted from one transmitter to multiple receivers with various locations. Moreover, encoding N various signals simultaneously in one transmitter and sending them at the same time to N various receivers separately, is also demonstrated. As a proof-of-concept, four different gray images are coded by one transmitter simultaneously and multicast to four various receivers separately. The favorable decoding results returned by the four receivers show good multicasting performance.