学术报告（10月17日 周三 10:00-11:30）

主持人：董建文 教授

欢迎广大师生踊跃参与！

【报告摘要】

The talk is split into two parts.

(i) An Introduction to the science and history of optical tweezers (from a theorist’s perspective)

(ii) Optical Tractor Beam

Proposed in 2011 by several groups, the Lorentz force based optical tractor beam that attracts a particle in the far field backward provides a new degree of freedom to manipulate neutral particles. The experimental demonstration was reported soon after the prediction. And this phenomenon has attracted significant research and public interests. However, the applicability was severely limited by its microscopic pulling range. The dilemma is that the pulling range was limited by the range of the incident beam, where the smaller the half cone angle is, the longer the range, while the optical pulling force usually does not occur when the half cone angle is small.

Here, we considered the optical pulling force exerted on an anti-reflection-coated dielectric cylinder. Utilizing several independent but compatible mechanisms we completely overcome the short pulling range and achieved an optical force at a very small half cone angle, which corresponds to a macroscopic pulling range. We also found that the pulling effect has good tolerance of the half cone angle and the frequency of the incident light. With this Lorentz force based optical tractor beam, optical pulling at a macroscopic range is realizable not only in a background medium, but also in vacuum.

【报告人简介】

Dr. Jack Ng is an assistant Professor in the Department of Physics in Hong Kong Baptist University. His current research interest is on optical manipulation and advanced electromagnetic materials (such as metamaterials).