Directional and Singular Surface Plasmon Generation in Chiral and Achiral Nanostructures Demonstrated by Leakage Radiation Microscopy

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• 作者：Quanbo Jiang ; Aline Pham ; Martin Berthel ; Serge Huant ; Joel Bellessa ; Cyriaque Genet ; Aurélien Drezet
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：3
• 期：6
• 页码：1116-1124
• 全文大小：711K
• 年卷期：0
• ISSN：2330-4022

文摘

In this paper, we describe the implementation of leakage radiation microscopy to probe the chirality of plasmonic nanostructures. We demonstrate experimentally spin-driven directional coupling as well as vortex generation of surface plasmon polaritons (SPPs) by nanostructures built with T-shaped and Λ-shaped apertures. Using this far-field method, quantitative inspections, including directivity and extinction ratio measurements, are achieved via polarization analysis in both image and Fourier planes. To support our experimental findings, we develop an analytical model based on a multidipolar representation of Λ- and T-shaped aperture plasmonic couplers, allowing a theoretical explanation of both directionality and singular SPP formation. Furthermore, the roles of symmetry breaking and phases are emphasized in this work. This quantitative characterization of spin–orbit interactions paves the way for developing new directional couplers for subwavelength routing.