At the same power, the shorter the duration of the laser pulse, the greater the instantaneous power。When the laser pulse duration is as short as a quadrillionth of a second, the instantaneous peak power can exceed 100 trillion watts, more than the installed power of all power plants in the world combined。This is a femtosecond laser。

By adjusting the properties of femtosecond laser pulses in time domain, space domain and frequency domain，The femtosecond laser will become a handful of shapes and properties can be adjusted，An indestructible flexible tool，High precision cutting, drilling and leveling at micron and nano scales，It can even be regulated at the electronic level...Over 20 years ago，Jiang LAN sees great potential in femtosecond laser applications。

如今，School of Machinery and Vehicle, Beijing Institute of Technology，Jiang LAN and his team were the first in the world to predict the shape of femtosecond laser processing，A new principle of electron dynamic control manufacturing for femtosecond laser is proposed，It is the first to realize the active control of electronic level in laser manufacturing，The first cross-scale quasi-three-dimensional ultrafast continuous observation system was developed，It is the first to realize the observation of electronic level in laser manufacturing，It is the first to realize the major engineering application of femtosecond laser manufacturing，It is the first to realize the large-scale industrial application of femtosecond laser manufacturing。

Since the birth of the first ruby laser in 1960, scientists have continued to push the performance of lasers faster and more powerful。In the 1980s，The researchers found that when the laser pulse duration is as short as a quadrillionth of a second, the intensity exceeds the super-fast, super-strong range of a hundred trillion watts，Classical theoretical models have been unable to explain the mechanism of the interaction between the ultrafast electromagnetic field and matter，This has become a bottleneck restricting the development of femtosecond lasers。At the beginning of this century, Jiang LAN entered the field of femtosecond laser manufacturing research。

Jiang LAN developed a strong interest in physics when she was an undergraduate. "' Relativity 'and' quantum mechanics' were the directions I devoted myself to studying at that time, and high-energy beam manufacturing represented by laser was essentially the interaction between energy and matter, which was the direction I was very interested in."。

Professor Jiang LAN guided the students to carry out the experiment of femtosecond laser electron dynamic control processing

There is no team, no project, and her focus is only a research branch of the third-level discipline field. Recalling the situation of entering the field alone more than 20 years ago, Jiang LAN's mouth is filled with a happy and aftertaste smile。"It was a wonderful time to be alone and do research without interruption。”

Six years later, Jiang LAN made a breakthrough in the theoretical research of femtosecond laser manufacturing。He proposed an improved two-temperature model, extending the application range of the classical two-temperature equation from the electron low temperature region to any electron temperature range, and improving the prediction accuracy of femtosecond laser processing threshold。He established a plasma quantum model, predicted the shape of femtosecond laser processing for the first time, successfully predicted a series of important anomalous effects, and won extensive international experimental verification and positive evaluation, including Nobel Prize winners。

In 2006, Jiang LAN set up the first femtosecond laser manufacturing and application research team in Beijing Institute of Technology。

Yet another obstacle stood in the way of the team。Femtosecond laser processing efficiency is low, the accuracy is worse than the diffraction limit, the depth to diameter ratio is low, these "inherent defects" of femtosecond laser processing, it is the reason that femtosecond laser processing has not been applied for more than 20 years。

Jiang LAN applied his model to reveal that to solve the above problems, the core is "whether the local instantaneous electronic dynamics can be regulated".。According to his theoretical model prediction, Jiang LAN proposed a technical route that can realize the active regulation of local instantaneous electronic dynamics in laser manufacturing through femtosecond laser space-time shaping, and then control the processing results。This technological route greatly expands the extreme capabilities of laser manufacturing。With the support of this theoretical model, Jiang LAN's team increased the femtosecond laser processing efficiency by 56 times, the repeatable processing accuracy reached 1/14 of the wavelength, and the depth to diameter ratio limit was increased from 20∶1 to more than 5000∶1。

Subsequently, Jiang LAN proposed and led his team to develop a cross-scale quasi-three-dimensional ultrafast continuous observation system。"The observation system with peak frame rates of trillions of frames per second across 15 orders of time validates a new principle of femtosecond laser electron dynamic control manufacturing。"Jiang LAN said。

In the national "13th Five-Year Plan" scientific and technological innovation achievement exhibition, Jiang LAN's team's femtosecond laser electronic dynamic control manufacturing achievements were selected。The identification committee composed of 11 academicians commented: "The first to realize the active regulation of the electronic level in laser manufacturing and the industrialization and major engineering applications of femtosecond laser processing...Overall, it has reached the international leading level。”

When a layman walks into a femtosecond laser microfabrication lab, it is difficult to relate the large experimental equipment in front of him and the hundreds of optical lenses lined up on the workbench to real life。Researchers who have broken through basic scientific research have seen extremely broad application prospects。

Mobile phone screen profile cutting is the key technology of mobile phone manufacturing。"The structure of a mobile phone screen is like a multi-layer cake, with glass, polymer, metal, insulators and glue distributed on different layers。Jiang LAN said, "Where traditional knives are helpless, it is the femtosecond laser that shows its skill.。At present, using the new electronic dynamic control cutting process proposed by Jiang LAN, the femtosecond laser manufacturing equipment developed in cooperation with Dazu Laser has reached 60% of the global market share。

Professor Jiang LAN guides students to carry out femtosecond laser multi-scale observation experiment

The processing of three-dimensional complex microstructure of difficult-to-process materials is a world-class problem in the field of cutting-edge manufacturing。Jiang LAN invented new technologies such as electronic dynamic control holes, cutting, leveling and engraving, and led his team to develop a series of new equipment with major indicators significantly better than the international level, laying the cornerstone for 37 national major science and technology projects and national major equipment。

Jiang LAN said: "A strong manufacturing industry is the cornerstone of the construction of a strong country, and the strong manufacturing industry is often 20 years ahead of the establishment of a strong country.。”

During the "12th Five-Year Plan" period, high energy beam manufacturing has become a key support direction of the National Natural Science Foundation, Jiang LAN served as the person in charge of high energy beam and special energy field manufacturing, and led the writing of a series of plans in the field of high energy beam and special energy field of the National Natural Science Foundation since the "12th Five-Year Plan"。

During the "13th Five-Year Plan" and "14th Five-Year Plan" period, Jiang LAN served as the leader of the national key research and development plan "Additive Manufacturing and laser manufacturing" key special implementation plan preparation expert group, guide preparation expert group and overall expert group。He devoted a lot of time to the country's first major project in the field of advanced manufacturing。At present, 112 related research and development projects have been deployed, which has effectively promoted China's additive manufacturing and laser manufacturing to the first echelon in the world。

Zhang Xueqiang, who has been working in the institute for two years, still remembers the scene of listening to Jiang LAN's lectures at the University of California, Berkeley。"He talked about the technical progress of femtosecond laser manufacturing, and also talked about the potential application prospects of femtosecond laser manufacturing。Zhang Xueqiang said, "After the lecture, when we were communicating, he asked me 'would you like to do some real scientific research together', and this sentence called me back.。”

All the students in Jiang LAN's technical team know that Jiang opposes sending "water articles".。Doctoral student Lian Yiling explained: "The experiment done by others, take back and repeat, and then adjust the parameters;Or someone else's experiment, do it again with a different material, it's all "water article".。”

Professor Jiang LAN teaches postgraduate students

What is real research？Jiang LAN said: "Either make a breakthrough in the academic frontier to reach the sky and expand the field of human cognition;Either in the country's major needs and the main battlefield of the national economy to achieve the application of location, to overcome key technical problems。”

Strict requirements have brought out a strong scientific research echelon。Jiang LAN has trained 33 doctors and postdocs, 40% of whom are teaching in "double first-class" universities and 57% are working in national key industry-related research institutions。The doctoral students under his guidance have won the Chinese Society of Mechanical Engineering "Silver excellent mechanical doctoral thesis Award" 6 times, including silver award, bronze award, excellence award, good work award, "Challenge Cup" national competition grand prize, etc. 2 people were approved by the European Union "Marie Curie" scholars。So far, Jiang LAN has trained 9 national high-level talents。

Professor Jiang LAN teaches postgraduate students

In the Institute of Femtosecond Laser micro-nano Manufacturing of Beijing Institute of Technology, the application field of femtosecond laser is still making breakthroughs。Professor Li Xiaowei is working on a series of important applications for femtosecond laser manufacturing。Professor Hu Jie is focusing on the fusion of medical work, femtosecond laser technology can provide antibacterial, anticoagulant, drug-carrying medical equipment for bone tumor treatment。Professor Li Xin is focusing on the application of composite materials processing in aerospace。

In Jiang LAN's view, the indestructible characteristics of femtosecond lasers should also be the characteristics of a team interested in real scientific research。"Aiming at the forefront of science and technology to serve the needs of the country is the mission of our generation of scientific researchers, and it is also the secret of our work to continuously make breakthroughs.。"Jiang LAN said。