China’s AO-MDR Laser Link Delivers 1 Gbps from Geostationary Orbit

Chinese researchers have achieved a record-breaking 1 gigabit-per-second (Gbps) data downlink from a satellite in geostationary orbit (36,000 km above Earth) using an optical laser link – with a laser device as weak as a “night light” or candle in power scmp.com scmp.com. In a recent demonstration, a 2-watt laser beam transmitted data to a ground station at 1 Gbps, a speed about five times faster than SpaceX’s Starlink network typically delivers to users scmp.com interestingengineering.com. This milestone showcases a new technology dubbed “AO-MDR synergy,” which allowed the laser signal to punch through Earth’s turbulent atmosphere without significant quality loss scmp.com defencepk.com. The achievement, led by Prof. Wu Jian of Peking University of Posts and Telecommunications and Liu Chao of the Chinese Academy of Sciences, opens the door to next-generation satellite communications that rival terrestrial fiber-optic speeds.

Adaptive Optics + Mode Diversity (AO-MDR): How the Technology Works

At the core of this breakthrough is the AO-MDR synergy method – a combination of Adaptive Optics (AO) and Mode Diversity Reception (MDR). Atmospheric turbulence normally distorts and scatters laser beams, turning a tightly focused signal into a faint, hundreds-of-meters-wide patch by the time it reaches the ground scmp.com. AO tackles this by sharpening the distorted wavefront of the incoming laser light in real time, using deformable mirrors to cancel out atmospheric blurring scmp.com defencepk.com. MDR, on the other hand, captures multiple spatial modes of the incoming light – essentially grabbing the various distorted copies of the signal that the atmosphere creates – and filters out the noise by picking the best ones scmp.com ts2.tech.

In the Chinese experiment, these two techniques were deployed together. The team’s ground receiver featured a 1.8‑meter telescope equipped with 357 tiny computer-controlled mirrors that continually adjusted to correct the incoming laser beam’s wavefront distortions defencepk.com. After this adaptive optics correction, the beam was fed into a multi-plane light converter that split it into eight parallel optical channels (modes) defencepk.com. A custom high-speed “path-picking” algorithm then analyzed these channels in real time and selected the three strongest, cleanest signal paths to extract the data interestingengineering.com defencepk.com. By always routing the data through the optimal modes, the system maintained a robust link even as the atmosphere shifted. “The AO-MDR method is ‘groundbreaking,’ allowing ‘a candle‑power laser to punch through turbulence’ at gigabit rates,” said Professor Wu Jian ts2.tech, whose team demonstrated that combining AO and MDR yields far better performance under strong turbulence than either technique alone scmp.com.

Key technical details of the AO-MDR laser link:

• Low-power laser, long distance: Only a 2 Watt laser on the satellite was needed to reach 1 Gbps over 36,000 km, thanks to the turbulence correction – a laser so weak it was described as “dim as a candle” scmp.com. This extremely high link efficiency far exceeds typical satellite internet downlinks (Starlink’s individual downlink is on the order of 100–200 Mbps) ts2.tech.
• Large aperture and adaptive optics: A 1.8 m diameter ground telescope collected the beam, and a 357-actuator deformable mirror (AO system) inside it continuously refocused the light, undoing atmospheric distortions in real time defencepk.com. This kept the beam sharp and greatly improved signal strength.
• Mode-splitting receiver: The corrected beam was sent through an optical multi-plane converter, splitting it into 8 distinct spatial mode channels interestingengineering.com. Each channel carried the same data through a slightly different path (mode) of the fiber, capturing the energy that turbulence might otherwise defocus.
• Real-time channel selection: A custom chip-based algorithm evaluated all eight channels each moment and picked the top 3 channels with the strongest, most coherent signals to actually decode interestingengineering.com. By always using the best subsets of light paths, the system avoided fade-outs.
• Improved signal reliability: According to the research team, this AO-MDR approach boosted the probability of usable signal reception from about 72% to over 91%, effectively reducing transmission errors dramatically defencepk.com timesofindia.indiatimes.com. In practical terms, that means a far more stable high-speed connection, with minimal data loss even in less-than-ideal atmospheric conditions.
• Infrared laser wavelength: The experiment used lasers in the 1.5 μm wavelength band (near-infrared), which is eye-safe and aligns with telecom fiber optics hardware global.jaxa.jp. This wavelength can carry huge bandwidth and is commonly chosen for free-space laser communications (for instance, JAXA’s and NASA’s laser comm systems also use ~1550 nm infrared light).
• Precision pointing and tracking: Keeping a laser on target over 36,000 km is like threading a needle from across a room. Both the satellite and ground station employed precision tracking systems to maintain alignment within micro-radians. The success demonstrates China’s advanced capability in pointing accuracy – a critical factor since a tiny drift could misalign the beam. (The satellite used in this test hasn’t been publicly named, as it’s described as a “secret” or classified experimental satellite scmp.com.)
• Clear-weather operation: Optical downlinks require clear skies – clouds or heavy fog will block the beam. The 1 Gbps test was conducted at Lijiang Observatory in southwest China interestingengineering.com, a high-altitude site likely chosen for its clear atmospheric conditions. To mitigate weather, operators can adopt strategies like multiple ground stations (ensuring at least one station is clear at any time) or even mobile ground terminals that reposition to find clear skies interestingengineering.com. In fact, Chinese engineers have developed truck-mounted optical ground stations to chase good weather when receiving data interestingengineering.com.

1 Gbps From GEO: A New Milestone in Space-to-Earth Communications

Achieving gigabit-per-second laser throughput from geostationary orbit (GEO) is a significant leap for space communications. GEO satellites orbit at about 35,786 km altitude, which means any signal to or from Earth must cross a huge distance through the atmosphere. Before now, most space-to-ground laser tests at such distances topped out at only a few hundred megabits per second. China’s new GEO laser link hitting 1 Gbps is the fastest on record for that orbit timesofindia.indiatimes.com. Remarkably, it maintained that data rate using very low laser power, thanks to the novel AO-MDR technique. “This method effectively prevents a drop in communication quality even when signal power is very low,” the researchers noted, citing multiple successful tests of their system interestingengineering.com interestingengineering.com. The results were peer-reviewed and published (June 2025) in the Chinese journal Acta Optica Sinica, underscoring that the experiment’s performance was rigorously verified defencepk.com.

For context, 1 Gbps is about 5× the speed of SpaceX’s Starlink internet downlink under similar conditions scmp.com. Starlink’s user terminals in practice see 100–300 Mbps in good conditions, and up to ~600 Mbps maximum per single satellite link under ideal scenarios ts2.tech. The Chinese GEO laser, however, delivered 1000 Mbps from tens of thousands of kilometers away. Even accounting for Starlink’s advantage of being in low Earth orbit (~550 km) with far less path loss, the Chinese demonstration’s throughput is extraordinary. The South China Morning Post quipped that Starlink “maxes out at a couple of Mbps” under heavy atmospheric fading, making the 1 Gbps GEO laser link “five times faster” in that challenging context ts2.tech.

Equally important is the data integrity and low error rate achieved. In high-speed links, especially optical ones, atmospheric turbulence can cause rapid signal dropouts and bit errors. By boosting the percentage of “usable” signal frames from ~72% to 91.1% defencepk.com, the AO-MDR system ensures that even high-value, high-bandwidth data (such as streaming HD video or scientific imagery) arrives with minimal loss or glitches interestingengineering.com interestingengineering.com. For example, beaming a high-definition movie via satellite normally risks dropped frames and pixelation if the link is unstable, but the improved stability means a smooth, error-free transmission interestingengineering.com. This reliability at high rate is a critical validator for laser comm technology – it’s not just about raw speed, but delivering error-free data.

Notably, this achievement did not come out of nowhere. China has been investing in laser communications research for years, and this demonstration builds on earlier successes. In fact, back in 2020, China’s Shijian-20 satellite (a large experimental GEO satellite) set a world record with a 10 Gbps laser downlink from GEO timesofindia.indiatimes.com. That 10 Gbps test, however, likely used a much more powerful laser and conventional tech (its exact power levels remain classified) timesofindia.indiatimes.com. The new AO-MDR experiment stands out because it reached gigabit speeds with minimal laser power, using innovative optics to overcome turbulence rather than brute force. In other words, China has shown it can attain GEO broadband links efficiently. This is prompting international notice: analysts have called it “an astonishing feat that could revolutionize global data exchange” ts2.tech and evidence that China is now at the forefront of space-based laser com technology.

How It Compares to Other Laser Communication Efforts

High-speed laser links in space are a growing focus around the world. China’s latest 1 Gbps GEO downlink and its plans for even faster laser networks invite comparison with other agencies and companies pushing optical communications:

• NASA (USA) – LCRD and TBIRD: NASA’s Laser Communications Relay Demonstration (LCRD), launched to GEO in 2021, is a testbed that can downlink data at up to ~1.2 Gbps over infrared lasers nasa.gov. This nearly doubled the previous NASA record set by the 2013 Lunar Laser Comm Demo (622 Mbps from the Moon). In low Earth orbit, NASA’s experimental TBIRD CubeSat shattered records by transmitting up to 200 Gbps to Earth in 2023 – sending 4.8 terabytes of data in a single ~5-minute pass nasa.gov. (TBIRD uses a “burst mode” laser transmitter and high-speed storage to achieve short bursts of extreme throughput.) These demos prove multi-Gbps laser links are feasible in LEO; the Chinese advance is demonstrating high rate from GEO.
• ESA (Europe) – EDRS “SpaceDataHighway”: The European Space Agency, with Airbus, operates the European Data Relay System (EDRS), a network of GEO relay satellites that use lasers to fetch data from lower satellites (like the Copernicus imaging fleet). EDRS’s laser terminals run at about 1.8 Gbps links between satellites esa.int eoportal.org. (Notably, EDRS then beams data down to Earth via radio due to weather concerns – optical downlinks to ground are the next frontier.) Europe is now planning an upgraded HydRON system to use optical links end-to-end.
• Japan – LUCAS relay system: In 2024, JAXA demonstrated 1.8 Gbps optical communication at 1.5 µm wavelength between a LEO Earth-observation satellite (ALOS-4 “Daichi-4”) and a GEO data relay satellite over 40,000 km apart global.jaxa.jp. This LUCAS system (Laser Utilizing Communication System) showed Japan’s ability to immediately downlink large volumes of data via a GEO relay, rather than waiting for the LEO to pass over ground stations global.jaxa.jp. Japan’s achievement is similar in speed to Europe’s, but like EDRS, the final hop to ground still relies on RF for now.
• Chinese Commercial Sector – Jilin-1 constellation: Beyond government projects, China’s private and commercial space industry is also racing ahead. In late 2023, Chang Guang Satellite Technology (which operates the Jilin-1 Earth-imaging constellation) achieved a 10 Gbps laser downlink from a LEO satellite to a mobile ground station interestingengineering.com. Shortly after, in 2024, they hit an astonishing 100 Gbps in a space-to-ground laser test – “ten times faster than their previous record” interestingengineering.com interestingengineering.com. This was done with a compact laser terminal (~backpack-sized) on a satellite and a truck-mounted optical ground station interestingengineering.com interestingengineering.com. It even prompted company officials to boast that while “Starlink… hasn’t deployed laser satellite-to-ground communication yet… we’ve already started large-scale deployment” of this tech interestingengineering.com. (Starlink uses laser links between satellites in space, but not to ground). China plans to equip all Jilin-1 satellites with these laser units, aiming for ~300 satellites by 2027 all capable of fast optical downlinks interestingengineering.com interestingengineering.com.
• SpaceX Starlink and others: SpaceX’s Starlink constellation pioneered the use of laser inter-satellite links in LEO – reportedly at speeds of up to ~100 Gbps per link for their newest satellites ts2.tech – to route data in space. However, Starlink currently downloads to users via radio (Ku/Ka band). SpaceX has not yet attempted operational laser links from satellites direct to individual user terminals (which would be challenging due to weather and terminal complexity). Other companies and agencies are developing optical comm as well: for instance, startups are testing 400 Gbps-class inter-satellite laser links ts2.tech, and France recently launched the Keraunos experiment (late 2023) to trial high-speed space-to-earth laser communications for defense globaltimes.cn afcea.org. The U.S. military and NASA are also planning laser links for the moon and deep-space missions (e.g. NASA’s upcoming Orion Artemis II optical terminal will beam back ultra-high-definition video from lunar distance) nasa.gov nasa.gov.

Where does China’s AO-MDR laser link stand? In terms of raw speed, 1 Gbps from GEO is on par with the best Western optical GEO demos (NASA’s LCRD ~1.2 Gbps) and far above any prior reported GEO-to-ground link in error-free performance. While NASA’s 200 Gbps TBIRD and China’s own 100 Gbps Jilin tests eclipse it in speed, those were done from LEO orbit (only a few hundred km up) where atmospheric distortion is easier to manage and link distances are much shorter. The novelty of the Chinese AO-MDR demonstration is achieving a gigabit link from GEO with such low power and high stability, something not yet seen elsewhere ts2.tech. This suggests that with further scaling (more power or multiple parallel beams), multi-gigabit laser downlinks from GEO are within reach. Indeed, China’s earlier Shijian-20 experiment hit 10 Gbps, and combining that experience with AO-MDR’s efficiency, future GEO satellites might reliably push tens of Gbps down to Earth – an unprecedented capability.

Implications for Satellite Internet, Deep Space, and Earth Observation

The success of China’s AO-MDR laser link carries far-reaching implications for the future of communications and space technology:

• High-Speed Satellite Internet Backbones: Laser communications promise to dramatically boost the bandwidth of satellite internet networks. A 10 Gbps (or higher) downlink from GEO could serve as a fat “trunk line” feeding data into local networks on the ground. For example, a single GEO laser satellite could beam internet data to a remote region’s ground hub, which then distributes it via Wi-Fi or fiber to end users. This could complement low-orbit constellations – GEO sats have high latency (~240 ms) but wide coverage, so they might deliver broadband to places with no fiber infrastructure (rural or offshore sites), or provide backhaul links between continents. The Chinese team’s innovation indicates that future 6G networks might integrate satellite lasers for ultra-fast global backbones interestingengineering.com. As one tech journalist noted, bandwidth alone isn’t the revolution – the revolution is doing it with so little power from GEO, which could make space-based internet hubs far more energy-efficient ts2.tech.
• Remote Sensing and Earth Observation: Modern observation satellites (imaging, climate monitoring, etc.) generate huge volumes of data – high-resolution images, radar maps, video, etc. Traditionally, they store data onboard and trickle it down to ground stations when in view, which can cause delays or data bottlenecks. Laser downlinks change that. With gigabit+ rates, satellites can dump data to Earth in real time or near-real-time. The Chinese experiment and others like Jilin-1’s 100 Gbps test show that even commercial imagery satellites can rapidly send terabytes of data to ground, enabling timely intelligence and monitoring interestingengineering.com interestingengineering.com. JAXA’s recent LUCAS demo likewise proved a satellite could immediately relay a large batch of Earth observation data via GEO in one pass, whereas it would have taken multiple orbits with direct downlinks global.jaxa.jp. Faster downlinks mean more frequent updates (e.g. hourly satellite images instead of daily) and the ability to support data-intensive applications like live 4K video from orbit or continuous disaster surveillance from space.
• Deep Space Communication: Laser links will be crucial for future missions to the Moon, Mars, and beyond. Radio frequency (RF) communications are reaching their limits in bandwidth – there’s only so much data you can send through NASA’s Deep Space Network or similar systems. Lasers, by contrast, can transmit much more data with the same aperture sizes. NASA has already tested a laser link from lunar orbit (LADEE’s LLCD in 2013) and is planning an optical terminal for the Orion spacecraft (Artemis II) to send back high-definition video nasa.gov. A GEO laser comm node like China’s could be a model for a lunar relay satellite or Mars orbiter using AO techniques to beam back science data at high rates. Imagine rovers on Mars sending ultra-HD panoramas or entire research datasets to an orbiter, which then lasers them tens of millions of kilometers to Earth. The Chinese AO-MDR method – using adaptive optics on the receiver – might even be applied in reverse for an Earth-based transmitter sending a clean laser uplink to distant probes. High-capacity deep-space optical links would enable richer scientific returns (for instance, streaming video from the surface of Mars, or massive data downloads from space telescopes). NASA officials have emphasized that laser comm can “pack significantly more data in a single link” than RF, which is “ideal for missions that need large data transmissions” nasa.gov.
• Secure and Interference-Resistant Comms: Optical links are generally narrow-beam and hard to intercept or jam, which is attractive for both commercial privacy and military security. Unlike radio beams that spread out and can be detected or interfered with over large areas, a laser link is so directed that only the intended receiver (telescope) can effectively pick it up. This inherent security, plus the fact that lasers don’t interfere with other systems (no spectrum licensing needed), means satellite lasers could handle sensitive communications (banking data, government transmissions) with lower risk of eavesdropping or congestion. China’s push in this area is likely driven in part by strategic motives – for example, a robust network of laser-linked satellites could be more resilient against electronic warfare (as it can’t be easily jammed like radio) ts2.tech ts2.tech. The flip side is that the same precision technology could have dual-use potential (e.g. high-power lasers to disable adversary satellites), which is why these developments are closely watched by defense communities ts2.tech ts2.tech. But purely on the communications side, the laser approach provides a new level of data security and capacity for future space-based internet.
• Future Missions and Deployments: China’s demonstration is likely just the start of operational uses. The researchers behind AO-MDR have proven the concept; we can expect this tech (or its evolutions) to be integrated into China’s satellite fleets. For instance, China’s next-generation GEO communications satellites or relay satellites for its space station could adopt adaptive-optics-enhanced laser downlinks to boost bandwidth. Large-scale constellations in LEO might use optical interlinks and downlinks to ground hubs, reducing reliance on radio spectrum. The country’s plans for a lunar base and deep-space exploration will undoubtedly include laser communication channels for high-data-rate links back to Earth. In short, the successful 1 Gbps test signals that China is moving aggressively to embrace laser communications for both civilian and strategic space infrastructures interestingengineering.com ts2.tech. This will likely spur international competition: the U.S., Europe, and Japan are already advancing their own systems, and now they have a clear benchmark to meet or exceed. As one IEEE analyst noted, 100+ Gbps laser links have been demonstrated in orbit, “so bandwidth alone is not revolutionary; the novelty [here] is doing it with such little power from GEO”, highlighting that the race is now about efficiency and reliability at distance ts2.tech.

In summary, China’s AO-MDR laser link experiment is a watershed moment for space communications. It combined cutting-edge optics and intelligent signal processing to break through a long-standing barrier – sending a high-speed data beam from a high orbit to the ground with minimal power and error. The 1 Gbps GEO downlink, and the prospect of 10 Gbps-class links to follow, suggest that fully optical networks in space are becoming a reality. We are looking at a future where satellites can stream massive amounts of data to Earth in real time, enabling everything from global broadband internet, to instantaneous Earth observation data, to rich media from deep space. As a Chinese researcher involved in the project put it, this development “opens doors to a new era of space-based technologies” interestingengineering.com interestingengineering.com – one where laser beams might carry the world’s information swiftly and securely across the heavens.

Sources:

• South China Morning Post – Stephen Chen, “Chinese satellite achieves 5 times Starlink speed with 2-watt laser from 36,000 km orbit” (June 17 2025) scmp.com scmp.com
• Interesting Engineering – “5× faster than Starlink: Chinese satellite beams data with minimal laser power” (June 2025) interestingengineering.com interestingengineering.com
• Samaa News – “China’s new laser satellite five times faster than Starlink” (June 17 2025) defencepk.com defencepk.com
• Times of India – “Chinese researchers achieve internet 5× faster than Starlink using 2-watt laser” (June 23 2025) timesofindia.indiatimes.com timesofindia.indiatimes.com
• Acta Optica Sinica (Chinese Optics Journal) – Wu Jian et al., results of AO-MDR experiment (June 3 2025) timesofindia.indiatimes.com
• Interesting Engineering – “China beats Starlink with 10× faster 100 Gbps space-ground laser transmission” (Jan 2 2025) interestingengineering.com interestingengineering.com
• NASA SCaN Program – “NASA’s Record-Breaking Laser Demo Completes Mission” (Sept 25 2024) nasa.gov nasa.gov
• JAXA Press Release – “World’s First 1.5 μm 1.8 Gbps Optical Inter-Satellite Communication (LUCAS)” (Jan 23 2025) global.jaxa.jp global.jaxa.jp
• IEEE Spectrum – A. Jones, “China Pioneers High-Speed Laser Links in Orbit” (2025) ts2.tech (cited via TS2 Tech)
• TS2 Technology – M. Frąckiewicz, “Space-Laser Shockwave: Inside China’s 2-Watt Orbital Beam…” (June 22 2025) ts2.tech ts2.tech