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

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。

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.