Metasurfaces have provided a flexible platform for designing ultracompact metalenses with unusual functionalities. However, traditional multi-foci metalenses are limited to generating circularly polarized (CP) or linearly polarized (LP) focal points, and the intensity distributions are always inhomogeneous/chaotical between the multiple focal points. Here, an inverse design approach is proposed to optimize the in-plane orientation of each meta-atom in a terahertz (THz) multi-foci metalens that can generate multi-polarized focal points with nearly uniform intensity distributions. As a proof-of-principle example, we numerically and experimentally demonstrate an inversely designed metalens for simultaneously generating multiple CP- and LP-based focal points with homogeneous intensity distributions, leading to a multi-polarized image (rather than the holography). Furthermore, the multi-channel and multi-polarized images consisting of multiple focal points with homogeneous intensity distributions are also numerically demonstrated. The unique approach for inversely designing multi-foci metalens that can generate multi-polarized focal points and images with uniform intensity distributions will enable potential applications in imaging and sensing.

中文翻译：

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太赫兹超透镜用于生成多偏振焦点和具有均匀强度分布的图像

超表面为设计具有不寻常功能的超紧凑超透镜提供了一个灵活的平台。然而，传统的多焦点超透镜仅限于生成圆偏振（CP）或线偏振（LP）焦点，并且多个焦点之间的强度分布总是不均匀/混乱。在这里，提出了一种逆向设计方法来优化太赫兹（THz）多焦点超透镜中每个超原子的面内取向，该超透镜可以生成具有几乎均匀强度分布的多偏振焦点。作为原理验证的示例，我们通过数值和实验演示了一种逆向设计的超透镜，用于同时生成具有均匀强度分布的多个基于 CP 和 LP 的焦点，从而产生多偏振图像​​（而不是全息图像）。此外，还对由具有均匀强度分布的多个焦点组成的多通道和多偏振图像​​进行了数值演示。逆向设计多焦点超透镜的独特方法可以生成多偏振焦点和具有均匀强度分布的图像，这将在成像和传感方面实现潜在的应用。