报告时间：3月1日 周五 上午10:00
报告人：Prof. Wenshan Cai (Georgia Institute of Technology)
报告题目： Electrically Activated Nonlinear Plasmonics
Nanostructured metals have offered not only the unprecedented opportunity to generate unconventional electromagnetic properties that are not found in nature, but also the exciting potential to create customized nonlinear media with tailored high-order effects. Two particularly compelling directions of current interests are active nanophotonics, where the optical properties can be purposely manipulated by external stimuli, and nonlinear optics, which enable intensity-dependent frequency conversion of light. By exploring the interaction of these two directions, we leverage the electrical and optical functions simultaneously supported in nanostructured metals and demonstrate electrically-activated nonlinear processes from plasmonic metamaterials. We show that a variety of nonlinear optical phenomena, including the wave mixing and the optical rectification, can be purposely modulated by applied voltage signals. In addition, electrically-induced and voltage-controlled nonlinear effects facilitate us to demonstrate the backward phase matching in a negative index material, a long standing prediction in nonlinear metamaterials. Furthermore, we show that the generation of thermal and nonthermal hot carriers via the nonradiative decay of plasmons allows for the sub-picosecond control of light properties in plasmonic systems, in an all-optical fashion. Our results reveal a grand opportunity to exploit plasmonic systems as self-contained, dynamic electrooptic systems with intrinsically embedded electrical functions and optical nonlinearities.
Wenshan Cai is an Associate Professor (tenured) in Electrical and Computer Engineering at the Georgia Institute of Technology, with a joint appointment in Materials Science and Engineering. Prior to joining Georgia Tech in 2012, he was a postdoctoral fellow at Stanford University. Dr. Cai received his B.S. and M.S. degrees from Tsinghua University in 2000 and 2002, respectively, and his Ph.D. from Purdue University in 2008. His research is in the area of nanophotonic materials and devices, in which he has made a major impact on the evolving field of plasmonics and metamaterials. Dr. Cai has published more than 50 journal papers in prestigious journals such as Science, Nature Materials, Nature Photonics, Nature Nanotechnology, etc., and the total citations of his recent papers have reached more than 10,000 within the past 10 years. He authored the book, Optical Metamaterials: Fundamentals and Applications, which is used as a textbook or a major reference around the world. Dr. Cai is the recipient of several national and international distinctions, including the OSA/SPIE Joseph W. Goodman Book Writing Award (2014), the CooperVision Science & Technology Award (2016), and the Office of Naval Research Young Investigator Award (2017).