China Youth Daily·China Youth Network Intern Reporter Yang Jie
Institute of Physics, Chinese Academy of Sciences, researcher Lu Ling is engaged in the "Dirac Vortex" topology optical cavity research, for ordinary people, is just an obscure academic concept.
However, from principle to sample, the topological cavity surface emission laser chip developed by the L01 group of the Institute of Physics Photo Physics Laboratory has the potential to change people's lives. It will be possible to use it in the fields of mobile phone face recognition, lidar for autonomous driving, and virtual reality for three-dimensional perception.
In the eyes of this young scientific researcher born in the 1980s, "a good scientific research project that can be constantly striving for is either on the 'book shelf' or on the 'shelf'. Of course, it is best to be on both."
The picture is Lu Ling. Photo provided by , Institute of Physics, Chinese Academy of Sciences
In March this year, Lu Ling's team's scientific research results were made public to the public. They successfully applied the "Dirac vortex" topological optical cavity discovered in previous research to surface-emitting semiconductor lasers, which can break through the current technical bottleneck of semiconductor laser in principle, and at the same time improve its exit power and beam quality to orders of magnitude.
The semiconductor laser chips used in daily life, such as the edge-emitting laser used in Internet communication, or the face-emitting laser used in mobile phone face recognition, were designed and developed by American and Japanese scientists about 50 years ago. Such devices have reached their own bottlenecks in terms of performance and indicators. At present, the development of emerging industries such as face recognition, autonomous driving, and three-dimensional perception has continuously improved the performance requirements of semiconductor lasers, and the problems of low exit power and poor beam quality need to be solved urgently.
"The function of semiconductor lasers is like the 'eye' of an unmanned driving system. If the lidar power is low, it means not looking far, and poor beam quality means seeing blur." Lu Ling explained that topological cavity surface-emitting lasers can solve the problem of "poor eyesight" in smart products and greatly improve the detection effect of lidar.
can "visual correction" is not a one-day effort, and it is not easy to do a pioneering research around the world. Lu Ling's doctoral thesis topic is photonic crystal semiconductor laser. Since his postdoctoral stage in 2010, he has been engaged in topological photonics research that was still unknown at the time. The name of this field is now derived from his 2014 review article on topological photonics. The underlying mathematical principles and new phenomena of topological photonics are not available in the current textbooks of optics and electromagnetics, which also means that this new direction has the possibility of bringing changes to the existing photonics technology.
More than Nobel Prize in Physics was born from the field of topological physics. The combination of topology and physics found that when external conditions change significantly, the physical properties of the system can maintain the magical robust characteristics. So theoretically, the topological stability principle should significantly improve the performance of various devices, but it has always been a "no man's land" in specific prototype devices.
"My current job is to develop a topological semiconductor laser device originally created by China and can be applied on a large scale." After returning to China in 2016, Lu Ling led his team to conduct research on the principle of improving semiconductor laser chip performance; afterwards, he received support from the first batch of projects such as the Chinese Academy of Sciences stable support youth team plan in the field of basic research.
During the scientific research stage, his brain often thinks "at the right time" and even thinks about problems anytime and anywhere while eating and walking. Sometimes when I talk to my wife, I am stunned and unconsciously think of scientific research issues. The outside world's voice is automatically blocked, and it takes a long time to remember the conversation. Every night when he is lying in bed, his brain will start to automatically review, thinking about what difficulties he encounters today and what aspects of the problems may occur. When he opened his eyes the next morning, the first thing he thought about was how to solve the "difficult we encountered yesterday". The breakthrough in the research of
topological cavity surface emission laser came from Lu Ling's inspiration when he wrote the article.He suddenly realized that the design of mainstream commercial semiconductor lasers and abstract one-dimensional topological models can be connected, and the underlying mathematical structure is actually exactly the same. A Lenovo , an interdisciplinary field, helped him find a way to crack the problem of semiconductor lasers, which is to generalize it from one-dimensional to two-dimensional topological design.
"The idea suddenly became clear and there was a directional breakthrough in future research." He checked the literature as soon as possible to verify whether there were loopholes in his thinking, whether it had been proposed by his predecessors, and whether it was really feasible.
In early 2022, the topological cavity surface emission laser was born in of the Chinese Academy of Sciences, achieving indicators and performance far exceeding similar commercial products. The research results of Lu Ling's team were published on the website of Nature Photonics magazine on March 18, 2022. The topological cavity is the "Dirac Vortex" topological cavity proposed by Lu Ling's team two years ago. It is the best known large-area single-mode optical cavity design. The results were published in the 2020 Nature Nanotechnology magazine. The large area here increases the laser power, while the single-mode energy ensures the beam quality.
In recent years, new students have come to visit, but they are not necessarily willing to persevere. Students who stay in the research group may have to bear the risk of delaying graduation and small number of papers published. Lu Ling hopes that in the future, there will be more young people willing to challenge first-class work in the scientific research environment of the motherland. "If a person can invest in a truly meaningful research when he is young, it is a great opportunity. Before dawn comes, he must be patient."
From ideas to devices, Lu Ling's team spent as long as 6 years on cracking key issues of semiconductor lasers. But in Lu Ling's view, waiting is worth it. "A ambitious scientist will study an extremely meaningful scientific problem. Once this scientific problem is solved, it will either remain in the textbooks of the next generation for learning and reference; or it will become a new technology that can be used in life to change people's lives; of course, the ideal state is that both can be done." After learning the spirit of the 20th National Congress of the Communist Party of China, as a young scientific and technological worker committed to the research and development of China's original semiconductor devices, Lu Ling sighed that he should "think what the country thinks, be anxious about what the country is, and respond to the needs of the country" and contribute his own strength to achieving high-level scientific and technological self-reliance.
In the future, he is full of confidence that his scientific research results can "get on the shelves": if the topological cavity surface-emitting laser slowly moves from samples to large-scale commercial production, then in decades, every mobile phone, every car, and every robot will likely use this new light source. At that time, the semiconductor devices invented in my country will enter thousands of households on a large scale.
Source: China Youth Daily Client
