Optical spin-to-orbital angular momentum conversion in structured optical fields  

作　　者：Yang Zhao Cheng-Xi Yang Jia-Xi Zhu Feng Lin Zhe-Yu Fang Xing Zhu 赵阳;阳成熙;朱家玺;林峰;方哲宇;朱星(State Key Laboratory for Mesoscopic Physics,School of Physics,Peking University,Beijing 100871,China;Center for Nanoscale Science and Technology,Academy for Advanced Interdisciplinary Studies,Peking University,Beijing 100871,China;Collaborative Innovation Center of Quantum Matter,Beijing 100871,China;National Center for Nanoscience and Technology,Beijing 100190,China)

机构地区：[1]State Key Laboratory for Mesoscopic Physics,School of Physics,Peking University,Beijing 100871,China [2]Center for Nanoscale Science and Technology,Academy for Advanced Interdisciplinary Studies,Peking University,Beijing 100871,China [3]Collaborative Innovation Center of Quantum Matter,Beijing 100871,China [4]National Center for Nanoscience and Technology,Beijing 100190,China

出　　处：《Chinese Physics B》2020年第6期436-440,共5页中国物理B（英文版）

基　　金：National Key R&D Program of China(Grant Nos.2017YFA0205700,2015CB932403,and 2017YFA0206000);the National Natural Science Foundation of China(Grant Nos.21790364,11374023,61422501,11674012,61176120,61378059,6097701,and 61521004).

摘　　要：We investigate the dynamic quantities:momentum,spin and orbital angular momenta(SAM and OAM),and their conversion relationship in the structured optical fields at subwavelength scales,where the spin–orbit interaction(SOI)plays a key role and determines the behaviors of light.Specifically,we examine a nanostructure of a Ag nanoparticle(Ag NP)attached on a cylindrical Ag nanowire(Ag NW)under illumination of elliptically polarized light.These dynamic quantities obey the Noether theorem,i.e.,for the Ag nanoparticle with spherical symmetry,the total angular momentum consisting of SAM and OAM conserves;for the Ag NW with translational symmetry,the orbital momentum conserves.Meanwhile,the spin-to-orbital angular momentum conversion is mediated by SOI arising from the spatial variation of the optical potential.In this nanostructure,the conservation of momentum imposes a strict restriction on the propagation direction of the surface plasmon polaritons along the Ag NW.Meanwhile,the orbital momentum is determined by the polarized properties of the excitation light and the topography of the Ag NP.Our work offers insights to comprehend the light behaviors in the structured optical fields in terms of the dynamic quantities and benefits to the design of optical nano-devices based on interactions between spin and orbital degrees of freedom.

关 键 词：orbital angular momentum spin angular momentum spin-orbit interaction of light silver nanowire 

分 类 号：O43[机械工程—光学工程]