title: Dual-polarity plasmonic metalens for visible light.
abstract: Surface topography and refractive index profile dictate the deterministic functionality of a lens. The polarity of most lenses reported so far, that is, either positive (convex) or negative (concave), depends on the curvatures of the interfaces. Here we experimentally demonstrate a counter-intuitive dual-polarity flat lens based on helicity-dependent phase discontinuities for circularly polarized light. Specifically, by controlling the helicity of the input light, the positive and negative polarity are interchangeable in one identical flat lens. Helicity-controllable real and virtual focal planes, as well as magnified and demagnified imaging, are observed on the same plasmonic lens at visible and near-infrared wavelengths. The plasmonic metalens with dual polarity may empower advanced research and applications in helicity-dependent focusing and imaging devices, angular-momentum-based quantum information processing and integrated nano-optoelectronics.
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Chen
authors.forename: Lingling
authors.initials: L
authors.lastname: Huang
authors.forename: Holger
authors.initials: H
authors.lastname: Mühlenbernd
authors.forename: Guixin
authors.initials: G
authors.lastname: Li
authors.forename: Benfeng
authors.initials: B
authors.lastname: Bai
authors.forename: Qiaofeng
authors.initials: Q
authors.lastname: Tan
authors.forename: Guofan
authors.initials: G
authors.lastname: Jin
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhang
authors.forename: Thomas
authors.initials: T
authors.lastname: Zentgraf