China’s AO-MDR Laser Link Delivers 1 Gbps from Geostationary Orbit
A 2-watt laser on a geostationary satellite delivered a 1 Gbps downlink to Earth from 36,000 km away. The AO-MDR system combines Adaptive Optics and Mode Diversity Reception to overcome atmospheric turbulence. The ground receiver used an 1.8-meter telescope with a 357-actuator deformable mirror to correct wavefront distortions. After AO correction, the beam was split into eight spatial modes by a multi-plane light converter, with a path-picking algorithm selecting the three strongest modes to decode. Usable signal frames increased from about 72% to 91.1%, dramatically improving link reliability. The infrared wavelength was 1.5 micrometers, an eye-safe band common in telecom
