In view of wide applications of structured light fields and plasmonic vortices, we propose the concept of compound plasmonic vortex and design several structured plasmonic vortex generators. This kind of structured plasmonic vortex generators consists of multiple spiral nanoslits and they can generate two or more concentric plasmonic vortices. Different from Laguerre-Gaussian beam, the topological charge of the plasmonic vortex in different region is different. Theoretical analysis lays the basis for the design of radially structured plasmonic vortex generators and numerical simulations for several examples confirm the effectiveness of the design principle. The discussions about the interference of vortex fields definite the generation condition for the structured vortex. This work provides a design methodology for generating new vortices using spiral nanoslits and the advanced radially structured plasmonic vortices is helpful for broadening the applications of vortex fields.

鉴于结构光场和等离激元涡旋的广泛应用，我们提出了复合等离激元涡旋的概念，并设计了几种结构化等离激元涡旋发生器。这种结构化等离子体激元发生器由多个螺旋纳米缝组成，它们可以产生两个或多个同心等离子体激元。与Laguerre-Gaussian光束不同，等离激元涡旋在不同区域的拓扑电荷不同。理论分析为径向结构的等离激元涡发生器的设计奠定了基础，并通过几个实例的数值模拟验证了设计原理的有效性。有关旋涡场干扰的讨论确定了结构旋涡的产生条件。