The scattering of light by objects is a ubiquitous physical phenomenon in nature. For example, sunlight is scattered by atmospheric molecules and suspended particles, which results in various wonderful optical phenomena such as blue sky, white clouds and rainbows. At the same time, the phenomenon of scattering is also one of the cores of many optical sciences and technologies. However, the intensity of the scattering phenomenon depends greatly on the ratio of the wavelength of the incident light and the characteristic size of the scatterer. In general, compared to thelight wavelength of 10 μm, mid-infrared lightis less scattered by nanoscale structures. How to use the light scattering effect to realize the strong scattering of mid-infrared light by extreme nano-scale or even atomic-scale structures has great application significance for the fields of highly integrated optical devices and mid-infrared sensing.
The research group led by Professor Wei Cai and Jingjun Xu from School of Physics and Tedainstitute of applied physics in Nankai University has made a series of progress in the direction of nanoscale light manipulation after long time exploration, such as the optical properties of double-layer graphene under independent regulations of energy band and Fermi level (Nano Letters 21, 5151(2021)) and controllable modulation of graphene plasmon wave reflection by artificially induced electron-type boundaries (Advanced Materials, 29, 1701083(2017)).
Recently, based on theacoustic graphene plasmons mode in graphene/h-BN/Auheterostructure, they realized that mid-infrared light can be strongly scattered by atomic level height steps, even though the step height of the scatter is four orders of magnitude smaller than the incident free wavelength. Besides, the scattering of the mid-infrared light by individual scatterers can be controlled via electrical back gating.
The physical originsis the ultra-high localized properties of acoustic graphene plasmons, which can achieve about one hundred times compression of the wavelength of mid-infrared light. This research is of great significance for manipulating light using atomic-scale nanostructures, which was published online in the internationally renowned journal Nature Communications by the title of “Strong in-plane scattering of acoustic graphene plasmons by surface atomic steps”.
Nankai University is the first affiliation for the paper. Ni Zhang (doctoral student), Weiwei Luo (associate professor) and Lei Wang (associate professor of Xinyang Normal University, doctoral graduate of Nankai University) are the co-first authors. Professor Cai Wei and Professor Xu Jingjun of Nankai University are the co-corresponding authors. The research was funded by the Guangdong Provincial Basic and Applied Basic Research Major Project, the National Ministry of Science and Technology Key R&D Program, and the National Natural Science Foundation of China.
