Imagine beaming a HD movie from Shanghai to Los Angeles – crossing three Pacific widths – in less than five seconds using just a night light.
But from a secret satellite parked in stationary orbit more than 60 times higher, a team of Chinese scientists has used a 2-watt laser – dim as a candle – to push data through turbulent skies to Earth at 1Gbps, five times faster than Starlink.
Satellite laser downlinks are fast but they face a foe: atmospheric turbulence. It scatters light into extremely weak and fuzzy patches hundreds of metres wide by ground arrival.
Previous attempts by researchers from around the world have used adaptive optics (AO) to sharpen distorted light or mode diversity reception (MDR) to capture scattered signals – but neither sufficed alone under strong turbulence.
Led by Wu Jian, a professor from Peking University of Posts and Telecommunications, and Liu Chao from the Chinese Academy of Sciences, the team proposed what they called a “groundbreaking” solution: AO-MDR synergy.
