自旋-轨道相互作用下X型涡旋光束的传播特性  

Propagation Property of X-type Vortex Beam under the Interaction of SAM and OAM

作　　者：肖维维 张晗 赵馨颖 马洋 庞晓炎 XIAO Weiwei;ZHANG Han;ZHAO Xinying;MA Yang;PANG Xiaoyan(School of Electronics and Information,Northwestern Polytechnical University,Xi'an 710072,China;School of Physics&Information Technology,Shaanxi Normal University,Xi'an 710119,China)

机构地区：[1]西北工业大学电子信息学院,西安710072 [2]陕西师范大学物理学与信息技术学院,西安710119

出　　处：《光子学报》2022年第1期234-248,共15页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.11974281,12104283);陕西省自然科学基础研究计划(No.2020JM-116)。

摘　　要：研究了X型涡旋光束在左旋/右旋圆偏振状态下在紧聚焦系统中的传播特性,讨论了自旋-轨道相互作用下焦平面光强的横向焦移和传播方向旋转现象的特点及其调控方法。研究发现:相位分布因子c是X型涡旋光束产生横向焦移和光强旋转的主要原因,而半孔径角α、偏振态和拓扑荷数对光强分布均有调控作用;由于自旋-轨道相互作用,入射光为左旋圆偏振态与右旋圆偏振态时,聚焦场光强分布差异明显,相同点是焦平面上光强的轴向转折点均为csw=1,这与入射光为线偏振态时轴向转折点不同;在二阶情况下,虽然入射光为左旋和右旋圆偏振时,两者的横向焦移与光强旋转不同,但是两者的主要涡旋点的分布及其旋转行为是一致的。本文研究可为结构光场的调控提供参考。A vortex beam is a kind of beam with a spiral phase surface,and in the beam center there is a phase singularity, thus the intensity is zero. Vortex beams can theoretically carry Orbital Angular Momentum(OAM)with any mode,and the vortex beams of different OAM modes are orthogonal to each other. Because of these special properties,vortex beams have received extensive attention from researchers and have been widely applied in the fields of wireless communication,optical tweezers and microscopes.However,the most researches on vortex beams concentrated on the canonical ones,whose phase gradient is constant along a circular path around the vortex center. The canonical vortices can be simply expressed as Aein?(A is the amplitude of field,? is azimuthal angle and n reperents the topological charge of the vortex),which in many circumstances are usually called‘optical vortices’ for short. The‘noncanonical’means that the phase gradient of the vortex is not constant,while the topological charge is also the same as it in its‘canonical’counterpart. Actually,the noncanonical vortices were studied by several scientists,but only the forms of the noncanonical vortices satisfying the paraxial wave equation were taken into consideration. There,the‘noncanonical’vortices were also called‘anisotropic’vortices,since not only the phase but also the amplitude of such vortices was spatially anisotropic. The researches on the noncanonical vortex wave are mainly concentrated in the scalar field,such as the study of the trajectory of noncanonical vortices in free space,the phase singularity and energy flux of noncanonical vortex dipole Airy beams. Recently,PANG Xiaoyan et al proposed a new type of noncanonical vortex,named X-type(noncanonical)vortex. This vortex inherits and develops the conventional noncanonical vortex,i.e.,it no longer has a constant phase gradient around the beam center, while the intensity keeps invariant azimuthally. In this article,the X-type(noncanonical) vortex with left-handed circular/right-hande

关 键 词：非经典涡旋 自旋角动量 轨道角动量 紧聚焦 光场调控 

分 类 号：O436[机械工程—光学工程]