Dolphins blowing bubbles in the oceanarium, the airflow formed when dandelions fly in the mountains, the mushroom cloud generated by a nuclear explosion... These seemingly unrelated scenes all contain a fascinating vortex phenomenon, which has been widely studied and applied in various disciplines such as fluid mechanics. However, in the field of optics, can light achieve a vortex structure? This question is still a blank space in the international research community.
On the evening of June 2nd, Beijing time, in the International Laboratory of Future Optics led by Academician Songlin Zhuang at the University of Shanghai for Science and Technology, Professor Qiwen Zhan's Nanophotonics team filled this gap. Based on Maxwell's equations and optical conformal mapping, Professor Qiwen Zhan and his team have, for the first time internationally, theoretically derived and experimentally realized the exquisite optical vortex structure. This operation of creating various structures with light in spacetime has made the team the craftsmen of sculpting spatiotemporal light .
July cover article in Nature Photonics
The team's related research achievements, titled Toroidal vortices of light, were formally published in the top international journal Nature Photonics and selected as the cover article. The reviewers of the journal commented, I think this achievement is a very beautiful result, demonstrating a complex three-dimensional optical singular structure that has never been demonstrated before, as far as I know, and even no one has imagined. This is another breakthrough in controlling the spatial-temporal structure of light.
The discovery of this achievement provides a new approach for the generation and characterization of three-dimensional complex spatiotemporal light fields. It has significant and far-reaching implications for theoretical research in toroidal electrodynamics, toroidal plasma physics, optical symmetry and topology, quantum physics, astrophysics, as well as applications in optical sensing, optical manipulation, and optical information and energy transfer. This research was supported by the Key Program of the National Natural Science Foundation of China (NSFC92050202) under the Major Research Program of New-Type Optical Field Control Physics and Applications.
Optical conformal mapping achieves the mapping from a spatiotemporal vortex tube to a vortex ring.
In fact, this is not the first time that the team has achieved an internationally recognized breakthrough. In 2020, Qiwen Zhan led the team to publish a research paper titled Generation of spatiotemporal optical vortices with controllable transverse orbital angular momentum in Nature Photonics, which opened up a new dimension of photon orbital angular momentum and caused a photon hurricane in the field of optics. Building on this achievement, the team spent two years to theoretically and experimentally demonstrate the generation of optical toroidal vortices, thereby elevating the level of light manipulation to a whole new level.
Schematic diagram of the experimental setup
If the discovery of the photon 'hurricane' in 2020 can be compared to a 'bead' with a hole, then the current achievement is like stringing many photon 'hurricanes' into a circular 'bracelet'. Like a child doing handicrafts, we have achieved an unprecedented state of light field by 'manipulating' the spatiotemporal structure of the light field. In a sense, our work represents a paradigm shift in the spatiotemporal control of light fields. Qiwen Zhan popularized, leading the team to conduct preliminary research on the propagation of optical toroidal vortices, including stable propagation in negative dispersion media and phenomena such as splitting during long-distance propagation in air.
Experimental generation of photonic toroidal vortex: intensity and phase distribution of the optical vortex ring.
Why is it necessary to achieve a toroidal vortex structure in the field of optics? How can such a new achievement be made using common optical principles and basic experimental equipment internationally? According to Qiwen Zhan, scientific exploration is about constantly expanding the territory and thinking one step ahead compared to others. The continuous stream of basic innovative achievements by researchers may inspire other peers or interdisciplinary researchers, leading to the transformation of what was once considered impossible into possible. New applications also emerge as a result, demonstrating the ultimate significance of striving for basic innovation from 0 to 1.
[resources]
Link to the paper
https://www.nature.com/articles/s41566-022-01013-y
China Laser Magazine Publicity Links
https://mp.weixin.qq.com/s/mTFmCh5Pg5LAUu7HZGpV4A
