In the laboratory of the School of Optical-Electrical and Computer Engineering at the University of Shanghai for Science and Technology, two commonly used high-precision vibration isolation platforms are available. One of them is used in the field of ultra-fast pulsed light, while the other is utilized in the study of spatial light field regulation and the angular momentum of photon orbitals. These represent the two distinct research directions.
However, under the guidance of Academician Songlin Zhuang, the Nanophotonics team led by Professor Qiwen Zhan at USST has dedicated two years to creatively 'merge' these two fields into one. They have, for the first time, demonstrated a novel light field with spatiotemporal vortex phases, carrying transverse photon orbital angular momentum from theory to experiments. This achievement introduces a completely new degree of freedom in photon orbital angular momentum. The research findings have been published in the prestigious optics journal, Nature Photonics, and were successfully chosen as one of the world's 30 major optical advancements in 2020 by the Optical Society of America (OSA). It's worth noting that only four institutions in China were selected, and USST is an independent completion unit.
Zero to one breakthrough, try out the photon 'hurricane'.
If the optical angular momentum trajectory has been likened to a tornado, then the recent discovery by Prof. Qiwen Zhan's team resembles the creation of a swiftly moving photon hurricane. This discovery not only offers a novel approach to material identification using light but also opens broader avenues for information transmission. It can be considered a groundbreaking advancement in the field of optics, transitioning from zero to one.
At the beginning, we were curious if we could transfer light from the ultrafast pulse platform to the spatial light field modulation platform. However, we soon realized that it wasn't as simple as a 1+1 equation. We embarked on a systematic integration of the experimental elements, effectively merging two previously distinct fields into a single experimental platform, Prof. Qiwen Zhan said.
Due to the sensitivity of scientific research, Professor Zhan Qiwen's team has creatively utilized the Fourier transform from the spatial-frequency domain to the spatial-temporal domain. They have successfully generated ultra-short optical pulse wave packets carrying transverse photon orbital angular momentum. This novel optical wave packet not only rapidly advances photon energy but also causes the photon energy flux to rotate around a transverse axis that moves with the wave packet. As a result, it forms a 'photon hurricane.'
Think one more step accidental discovery is actually the inevitable innovation.
In fact, the principles we employed are well-known to optical scientists, and the apparatus we developed is easily replicable. What sets us apart, on a global scale, is that we 'thought one step further' than others. Isn't that the allure of scientific research? Professor Zhan Qiwen said with a smile. In his view, scientific research should not be confined to textbooks. A chance discovery can lead to a paradigm shift in an entire field, and this is the driving force for researchers to go all out and strive for excellence.
It is understood that this discovery holds significant potential research and application value in various fields, including optical communication, optical information processing, quantum optics, particle manipulation, and relativistic space physics. Although Professor Zhan Qiwen's team's research findings have gained global recognition, they are well aware that the easier an experiment can be replicated, the fiercer the future competition will become. They cannot merely be the ones 'laying the foundation' but must rapidly proceed with a series of initiatives. The research team has recently secured key project support from the National Natural Science Foundation of China under the 'Major Research Program on Novel Light Field Control Physics and Applications.' They will further engage in comprehensive and in-depth research in this field and look forward to extensive collaboration with peers both domestically and internationally.
