Understanding the near-field electromagnetic interactions that produce optical orbital angular momentum(OAM)is crucial for integrating twisted light into nanotechnology.Here,we examine the cathodoluminescence(CL)of pl...Understanding the near-field electromagnetic interactions that produce optical orbital angular momentum(OAM)is crucial for integrating twisted light into nanotechnology.Here,we examine the cathodoluminescence(CL)of plasmonic vortices carrying OAM generated in spiral nanostructures.The nanospiral geometry defines a photonic local density of states that is sampled by the electron probe in a scanning transmission electron microscope(STEM),thus accessing the optical response of the plasmonic vortex with high spatial and spectral resolution.We map the full spectral dispersion of the plasmonic vortex in spiral structures designed to yield increasing topological charge.Additionally,we fabricate nested nanospirals and demonstrate that OAM from one nanospiral can be coupled to the nested nanospiral,resulting in enhanced luminescence in concentric spirals of like handedness with respect to concentric spirals of opposite handedness.The results illustrate the potential for generating and coupling plasmonic vortices in chiral nanostructures for sensitive detection and manipulation of optical OAM.展开更多
基金sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National LaboratorAdditional support was provided by the U.S.Department of Energy grant DE-FG02-09ER46554+3 种基金by the McMinn Endowment at Vanderbilt University(J.A.H.,S.T.P.)by the U.S.Department of Energy grant DE-FG02-01ER45916(R.B.D.,R.F.H.)support by NSF award DMR-1747426the Department of Defense(DoD)through the National Defense Science&Engineering Graduate Fellowship(NDSEG)program.
文摘Understanding the near-field electromagnetic interactions that produce optical orbital angular momentum(OAM)is crucial for integrating twisted light into nanotechnology.Here,we examine the cathodoluminescence(CL)of plasmonic vortices carrying OAM generated in spiral nanostructures.The nanospiral geometry defines a photonic local density of states that is sampled by the electron probe in a scanning transmission electron microscope(STEM),thus accessing the optical response of the plasmonic vortex with high spatial and spectral resolution.We map the full spectral dispersion of the plasmonic vortex in spiral structures designed to yield increasing topological charge.Additionally,we fabricate nested nanospirals and demonstrate that OAM from one nanospiral can be coupled to the nested nanospiral,resulting in enhanced luminescence in concentric spirals of like handedness with respect to concentric spirals of opposite handedness.The results illustrate the potential for generating and coupling plasmonic vortices in chiral nanostructures for sensitive detection and manipulation of optical OAM.
