学　术

　　由电子科学与工程学院主办的“电子论坛”第8期邀请到美国东北大学Dr. Yongmin Liu，与我校师生共同探讨手性光物质的相互作用。具体安排如下，欢迎感兴趣的师生参加。

　　主　题：Chiral light-matter interactions: from chiral metamaterials to all-optical switching of magnetization

　　主讲人：Dr. Yongmin Liu　（Northeastern University）

　　时　间：2018年5月7日（周一）14:00

　　地　点：清水河校区五号科研楼351

　　内容简介：

　　Chirality refers to the structural property of an object that cannot be superposed onto its mirror image. The existence of chirality in nature is universal, ranging from molecules at the nanoscale to gastropod shells at the macroscale. Light can be chiral as well. Circularly polarized light with opposite helicity has its electric field vector rotating clockwise or counterclockwise during propagation. Chiral light-matter interactions are widely used in molecule detection, optical communication and information processing. In this talk, I will discuss how to engineer the chiral light-matter interaction and utilize it for data storage based on innovative structures and materials. First, I will discuss a new concept of chiral metamirrors, which can achieve near-perfect reflection of designated circularly polarized light without reversing its handedness, yet complete absorption of the other polarization state. This metamirror can be considered as the optical analogy of beetle Chrysina gloriosa in nature, while exhibits nearly maximal efficiency. Second, I will present origami-based, dual-band chiral metamaterials at microwave frequencies. The flexibility in folding the metamaterial provides another degree of freedom for geometry control in the third dimension, which induces strong chirality from the initial, two-dimensional achiral structure. These results open a new avenue towards lightweight reconfigurable meta-devices. Finally, I will discuss all-optical helicity-dependent switching in hybrid metal-ferromagnet thin films, which consist of Co/Pt multilayers with perpendicular magnetic anisotropy covered by an Au film on the top. We find that in this system robust all-optical switching exists across a wide range of laser repetition rates and average powers, promising ultrafast magnetic storage devices for the Big Data era.

　　主讲人简介：

　　Dr. Yongmin Liu obtained his Ph.D. from the University of California, Berkeley in 2009. He joined the faculty of Northeastern University at Boston in fall 2012 with a joint appointment in the Department of Mechanical & Industrial Engineering and the Department of Electrical & Computer Engineering. Dr. Liu’s research interests include nano optics, nanoscale materials and engineering, plasmonics, metamaterials, biophotonics, and nano optomechanics. He has authored and co-authored more than 70 journal papers, including Science, Nature, Nature Nanotechnology, Nature Communications, Advanced Materials, Physical Review Letters and Nano Letters. Dr. Liu was a recipient of NSF CAREER Award (2017), Office of Naval Research Young Investigator Award (2016), SPIE DCS Rising Researcher Award (2016), 3M Non-Tenured Faculty Award (2016), Air Force Summer Faculty Fellowship (2015), and Chinese Government Award for Outstanding Students Abroad (2009). Currently he serves as an editorial board member for Scientific Reports, EPJ Applied Metamaterials and Nano Convergence.

　　　　　　　　　　　　　　　　　　　电子科学与工程学院

　　　　　　　　　　　　　　　　　　　　　2018年5月1日