A vectorial model for the nonlinear gradient force exerted on metallic Rayleigh nanoparticles
Z. Zhu (Zhejiang Lab, TU Delft - ImPhys/Adam group, Shenzhen University)
Yuquan Zhang (Shenzhen University, TU Delft - ImPhys/Optics)
Changjun Min (Shenzhen University)
Aurèle Adam (TU Delft - ImPhys/Adam group)
H. P. Urbach (TU Delft - ImPhys/Stallinga group)
Xiaocong Yuan (Zhejiang Lab, Shenzhen University)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Optical tweezers have proved to be a powerful tool with a wide range of applications. The gradient force plays a vital role in the stable optical trapping of nano-objects. The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping. However, when the third-order nonlinear effect of the nano-object is stimulated, the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field. Here, we propose a theoretical model to interpret the nonlinear gradient force using the vector method. By combining the optical Kerr effect, the polarizability vector of the metallic nanoparticle is derived. A quantitative analysis is obtained for the gradient force as well as for the optical potential well. The vector method yields better agreement with reported experimental observations. We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.