Optical force on toroidal nanostructures: Toroidal dipole versus renormalized electric dipole

作     者：Xu-Lin Zhang S. B. Wang Zhifang Lin Hong-Bo Sun C. T. Chan 

作者机构：Department of Physics and Institute for Advanced Study The Hong Kong University of Science and Technology Clear Water Bay Hong Kong China State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun China State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonics Structure (Ministry of Education) Fudan University Shanghai 200433 China Collaborative Innovation Center of Advanced Microstructures Fudan University Shanghai 200433 China 

出 版 物：《Physical Review A》 (物理学评论A辑：原子、分子和光学物理学)

年 卷 期：2015年第92卷第4期

页      面：043804-043804页

核心收录：

学科分类：070207[理学-光学] 07[理学] 08[工学] 0803[工学-光学工程] 0702[理学-物理学] 

基　　金：Hong Kong RGC [AOE/P-02/12, CUHK1/CRF/12G-1] NNSFC Ministry of Education of China [B06011] 

主　　题：NANOSTRUCTURES TOROIDAL harmonics ELECTRIC dipole moments RESONANCE ELECTROMAGNETIC fields 

摘      要：We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.