High-mobility 40-Gbps free-space optical link by a three-stage high-speed beam stabilizer and 2-D photodetector array based diversity reception

We experimentally demonstrated a mobile free-space optical link by a three-stage high-speed optical beam stabilizer and 2-D photodetector array based diversity reception. The spatial diversity reception by photodetector array and maximum-ratio combining based digital signal processing effectively mitigated the impacts of inevitable residual misalignment and wavefront distortion in a typical free-space optical system, which provided an 11.5°/s angular moving speed over a 2.1-m free-space distance with 40-Gbps data transmission. Compared with typical free-space optical systems, the proposed approach provided a wide field-of-view with mobility support, such as human support robots in future 6G indoor applications.