School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
Nat Commun. 2012;3:1198. doi: 10.1038/ncomms2207.
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.
表面形貌和折射率分布决定了透镜的确定性功能。迄今为止报道的大多数透镜的极性，即正（凸）或负（凹），取决于界面的曲率。在这里，我们实验演示了一种基于圆偏振光手性相关相位不连续性的反直觉双极性平面透镜。具体来说，通过控制输入光的手性，可以在同一个相同的平面透镜中实现正负极性的相互转换。在可见和近红外波长下，在同一个等离子体透镜上观察到了手性可控的实像和虚像焦平面，以及放大和缩小的成像。这种具有双极性的等离子体超透镜可能会为基于手性聚焦和成像器件、基于角动量的量子信息处理和集成纳光电学的先进研究和应用提供支持。
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