Generation of Tunable Plasmonic Vortices by Varying Wavelength of Incident Light

Abstract

Surfaces plasmon polaritons carrying orbital angular momentum (OAM), known as plasmonic vortex, hold potential applications for on-chip information multiplexing. However, a traditional plasmonic vortex lens was usually designed for monochromatic incident light and encountered challenges in generating multiple vortices. Here, we demonstrated a wavelength-tunable plasmonic vortex generator that ameliorates these limits, relying on the simultaneous design of a geometric metasurface on an Archimedean spiral. Through this design strategy, both the topological charges and the location of vortices can be controlled with different wavelengths of incident beams. This design and concept can preserve incident wavelength information and can be further applied to integrated and high-dimensional on-chip devices.