title: A spiral plasmonic lens with directional excitation of surface plasmons.
abstract: Conventional plasmonic lenses are composed of curved slits carved through metallic films. Here, we propose a new plasmonic lens based on a metallic slit with an auxiliary groove. When the lens is illumined normally, only inward surface plasmon polaritons (SPPs) can be generated and then focused into a hot spot at the center of the lens. The focusing effect is theoretically investigated by varying the groove parameters and incident polarizations. It is found that this phenomenon exists for both the circular and linear polarizations of incidence. Under optimal groove parameters, the intensity of the focal spot in our lens can be 2.5 times of that in one without grooves for both linearly and circularly polarized illuminations.
authors: Department of Materials Science, Laboratory of Advanced Materials and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China.
authors: Qingrui
authors: Q
authors: Guo
authors: Department of Materials Science, Laboratory of Advanced Materials and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China.
authors: Chi
authors: C
authors: Zhang
authors: Department of Materials Science, Laboratory of Advanced Materials and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China.
authors: Xinhua
authors: X
authors: Hu