报告题目：Momentum Effects of Light and Sound in Artificial Structures

报 告 人：Prof. Shubo Wang（City University of Hong Kong）

报告时间：2019年6月3日（周一）上午9:30

报告地点：物理学院新楼五楼报告厅

报告摘要：

Classical waves can carry both linear momentum and angular momentum. The interactions between waves and matter lead to momentum transfer/conversion that not only changes the propagation properties of waves but also induce forces on matter. These momentum effects can give rise to counterintuitive phenomena in artificial structures (i.e. man-made structures with desired properties). I will discuss several phenomena deriving from the momentum of light or sound. I will report that the light-induced force on a metamaterial boundary can be either pushing or pulling depending on the lattice symmetry of microstructures. I will also report that photonic spin-orbit interactions enabled by artificial microstructures can induce chirality-dependent lateral optical forces and arbitrary-order non-Hermitian exceptional points. Although sound is a scalar wave, I will show that its orbital angular momentum can give rise to spin-redirection geometric phase phenomena in helical waveguides. Interpretations of these phenomena help to resolve a century-old debate about photon momentum in media and deepen our understanding of different properties of spin and orbital angular momentum. Our studies could generate novel applications such as ultra-sensitive optical sensors and sorting chiral molecules using light-induced forces.

报告人简介：

Shubo Wang, Assistant Professor Department of Physics, City University of Hong Kong . His group is mainly engaged in theoretical research on optics. The main research directions are as follows: 1. Metamaterial and Photonic Crystal: With the material properties that do not exist in nature, they can realize the peculiar phenomena of negative refraction, cloak, topological transmission and so on.2. Optical force: Using a laser to manipulate objects at nano or micron scales. 3. Computational Electromagnetics: Develop a fast calculation method of electromagnetic waves.

His group not only concentrates on exploring the fundamental physics, but also looks for the efficient method to solve practical problem. He has wide communication and cooperation with many colleges, such as Fudan University, Nanjing University, Suchoow University, Huazhong University of Science and Technology. In recent years, more than 20 papers have been published, including 7 in Nature Communications, Science Advances, Physical Review Letters, Physical Review X and 9 in other Physical Review series. Some articles were selected as highlights of Editors' Suggestion and Nature Photonics' News and Views.

邀请人：肖孟 教授