Chinese scientists have sent data from a satellite 36,000 kilometers above Earth. They used only a 2-watt laser. This small laser uses about the same power as a nightlight. It managed to transmit data at 1 gigabit per second (Gbps). That is five times faster than what Starlink usually offers.
Starlink is Elon Musk‘s satellite internet service. It uses a large number of small satellites in low Earth orbit. These satellites are about 550 kilometers from Earth. They can send data at speeds of around 100 to 250 megabits per second (Mbps). That speed is good for general use. But the new Chinese system uses a 2-watt laser from a much higher orbit. It has shown that faster and more stable connections are possible using laser technology.
Professor Wu Jian from Peking University of Posts and Telecommunications led the project. Liu Chao from the Chinese Academy of Sciences also led the project. Their research appeared in the Chinese journal Acta Optica Sinica. It shows how they made this achievement using a new method called AO-MDR synergy. They did this with nothing more than a 2-watt laser.
Atmospheric turbulence is one of the biggest problems for laser communication from space. When laser beams pass through Earth’s atmosphere, they are scattered and distorted. This makes it hard to keep the signal clear and strong. Even a 2-watt laser faces this challenge.
Previous attempts used two methods separately. The first method is Adaptive Optics (AO). It helps reshape distorted laser beams. The second method is Mode Diversity Reception (MDR). It helps collect scattered light. But these methods alone were not enough to keep the signal stable.
The Chinese team decided to combine both AO and MDR. They created one powerful system. This new approach is called AO-MDR synergy. It fixed the laser signal. It also caught the useful scattered parts of the beam. This allowed the signal from the 2-watt laser to stay strong. It worked even though the laser was very weak and the satellite was extremely far from Earth.
To test this new method, the team set up a 1.8-meter telescope at the Lijiang Observatory in southwest China. Specifically, this telescope has 357 tiny mirrors. Moreover, these mirrors can move on their own. For example, they adjust in real-time to fix the incoming laser light. This is important because the atmosphere had bent and twisted that light. Once the laser light is corrected, it travels through a fiber. Then, a special converter splits it into eight signal paths.
An advanced computer algorithm then looks at these eight signals. It picks the best three. These are the signals that are the strongest and most stable. The system then uses these three channels to get the best quality data. Several rounds of testing confirmed the results. The success rate of getting usable signals went up from 72 percent to 91.1 percent.
Professor Wu Jian said, “This method effectively prevents communication quality degradation caused by extremely low signal power.” Liu Chao added that the results show how laser technology can beat current internet systems. It can do this even with fewer resources.
This success means that laser communication could soon replace traditional radio systems used in satellites. Radio waves are limited in how much data they can carry. Lasers can carry much more data. They are also much faster and more efficient. This could improve many areas of life. Examples include streaming HD videos, improving satellite TV, helping in scientific research, and supporting communication in space missions.
The 2-watt laser used in this test was very small. The setup did not require large or expensive ground systems. This could make it easier and cheaper to build such systems in the future. Even though the 2-watt laser had little power, it beat Starlink’s much larger system in speed.
Starlink offers lower latency. That is better for online gaming or video calls. Starlink also works well in bad weather because it uses radio waves. Laser systems like the one developed in China may not work as well in cloudy or stormy conditions. However, the Chinese system can transmit large amounts of data from a single high-orbiting satellite using a single 2-watt laser. This means fewer satellites are needed for global coverage.
