20 Gbps Free-Space Optical Chaotic Communication Based on Orbital Angular Momentum Multiplexing

We experimentally demonstrate a free-space all-optical chaotic communication system that enhances transmission capacity and security by orbital angular momentum (OAM) multiplexing. Optical chaotic signals with two different OAM modes carrying 20 Gbps on-off keying signals are secretly transmitted over a 2 m free-space link. Our work may inspire structured light application in optical chaos and pave a new way for developing future high-capacity free-space chaotic secure communication systems.