Free-Space Multi-Dimentional Mode Coding with Rotating Gear Beams Carrying Orbital Angular Momentum

The demand for high-dimensional coding techniques for communication systems is increasing. In this study, Laguerre-Gaussian (LG) beams is used as the basic mode of superposition, and specific parameters p, m
0
, n
0
, Ø are added in each superposition to generate a class of four-dimensional structured beams, which is called Rotating Gear Beams (RGBs). High-dimensional RGBs has a large number of available coding modes, which can effectively improve the resource utilization of existing dimensions, and expand the optical communication capacity, theoretically achieving a maximum coding of up to 1024 bits. We demonstrated the exceptional coding capability of RGBs by transmitting a 64-bit grayscale image. Our work will accelerate the development of future optical communications for higher capacity.