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基于狭槽天线超表面的复振幅光瞳滤波器

Complex amplitude pupil filters based on metasurface with subwavelength slot antenna

  • 摘要: 为了产生具有特殊性质的聚焦矢量光场,根据狭槽天线与线偏振片的相似性,设计了刻蚀有多个不同方向狭槽天线环形阵列的超表面,作为离散型复振幅光瞳滤波器使用。以径向偏振入射光为例,经该滤波器并经大数值孔径透镜紧聚焦后,可获得衍射受限的超长3维光管场。结果表明,由于狭槽天线具有局域调控入射光场振幅和相位的特性,各个环带上具有各自特定的透射率,同时具有特定的二元相移(0/π)分布,可以用来实现具有特殊性质的矢量光场。这种结构的超表面对矢量光束的产生与调控提供了新途径。

     

    Abstract: In order to generate vectorial focal field with special properties, according to the similarity between the slot antenna and linear polarizer, a metasurface with multiple subwavelength slot antenna arrays with different directions is investigated. It is used as a discrete pupil filter with complex amplitude. The incident radial polarized light passes through this filter and is focused by a high numerical aperture lens. Then the diffraction-limited ultra-long 3-D optical tube can be obtained in the focal region. Since the slot antenna can manipulate the amplitude and phase locally, every ring has its own transmittance and binary phase shift (0/π) so that it can be used to generate special vectorial focal field. This type of metasurface can guide us to find a new way for generation and manipulation of vectorial fileds.

     

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