报告题目：Forces between Neutral Nano Plasmonic Objects
报告时间： 2018年12月13日 上午10：00-11：00
Recent advances in nanotechnology make the fabrication of nano-corrugated plasmonic surfaces with controlled size and shape possible. The study of phenomena working at the nanoscale becomes important because many ignorable effects in the macroscopic level become dominant at that scale.
One interesting topic is about the possibility of realizing repulsive forces at the nano-scale. Such forces are important for manipulating nanoparticles and nano-assembly. Here we show that there is a kind of curvature-induced force that acts between nano-corrugated electrically neutral plasmonic surfaces. Absent in flat surfaces, such a force owes its existence entirely to geometric curvature, and originates from the kinetic energy associated with the electron density which tends to make the profile of the electron density smoother than that of the ionic background and hence induces curvature-induced local charges. We found that the force can be attractive or repulsive, depending on the details of the nano-corrugation.
Another interesting topic is about the optical force density distribution inside a material because it is not only crucial to understand opto-mechanical behavior in the nanosacle, but also challenging in the calculation where quantum and non-local effects emerge and macroscopic parameters such as permittivity become ill-defined. We demonstrate that the microscopic optical force density of nanoplasmonic systems can be defined and calculated using the microscopic fields generated using a self-consistent hydrodynamics model that includes quantum, non-local and retardation effects. This approach works even in the limit when the nanoparticles are close enough to each other so that electron tunneling occurs, a regime in which classical electromagnetic approach fails completely. Based on this technique, optical binding force and spinning torque of plasmonic dimers are studied in detail.
Dr. Kun Ding received his Bachelor degree from Fudan University in 2008, and got his PhD in physics from Fudan University in 2013 (supervised by Prof. Lei Zhou). From August 2013 to July 2018, he worked at Institute for Advanced Study of HKUST as a Post-doctoral Fellow (titled as Tin Ka Ping Fellow from Aug 2015 to July 2017) under Prof. Che Ting Chan. Starting from August 2018, he worked as a Research Assistant Professor at Department of Physics of HKUST. His current research topics are non-Hermitian physics in classical wave systems and quantum plasmonics.