18.06.2025
Chinese scientists use ‘groundbreaking’ method to push data through turbulent skies from Space to Earth in less than five seconds
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.
Network and satellite data exchange over planet earth in space 3D rendering elements of this image furnished by NASA. Photo: Shutterstock
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.
“This method effectively prevents communication quality degradation caused by extremely low signal power,” wrote Wu and Liu’s team in a peer-reviewed paper published in the Chinese-language journal Acta Optica Sinica on June 3.
They tested the system at a Lijiang observatory in southwest China using a 1.8-metre (5.9 feet) telescope targeting an unnamed satellite 36,705km (120,423 feet) away. Inside the telescope, there are 357 micro-mirrors that can reshape warped laser light and slash wavefront distortion.
A multi-plane converter (MPLC) splits light entering a multi-mode fibre into 8 base-mode channels. The three strongest signals were selected and merged in real time via a “path-picking” algorithm driven by tailor-made chips.
The researchers observe a surge in signal strength. AO+MDR added a significant gain over AO alone at critical signal-reliability thresholds.
“This multiplicative effect was consistently observed across multiple experimental verifications,” the team wrote.
The new method also reduces errors significantly. The chance of usable signals jumped from 72 per cent to 91.1 per cent – critical for the transmission of high-value data.
China plays a leading role in the development of space laser communication technology. In 2020, China’s Shijian-20 satellite hit 10Gbps laser downlinks from geostationary orbit – a world record.
But the laser power on Shijian-20 remains classified. The US military has reportedly sent a satellite to spy on Shijian-20 from a close distance, but the Chinese satellite moved away.
Quelle: smcp.com