We propose a three-dimensional freeform nanophotonic platform in which wavelength-scale domains comprise basic geometric structures with explicitly defined dimensions, positions, orientations, and minimum feature size constraints. Given a desired wavefront shaping objective, these parameters can be collectively optimized using gradient-based shape optimization with full accounting of near-field interactions between structures. We apply our concept to a variety of metagratings supporting high diffraction efficiencies and polarization control, and we experimentally demonstrate a device with a tailored polarization response as a function of wavelength. The combination of device capability, feature size constraints, and ease of manufacturability enabled by our methodology will facilitate the development of robust, high performance, nanophotonic technologies.

中文翻译：

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基于梯度的三维纳米光子器件逆向设计的重参数化方法

我们提出了一个三维自由形式纳米光子平台，其中波长尺度域包含具有明确定义的尺寸、位置、方向和最小特征尺寸约束的基本几何结构。给定所需的波前整形目标，可以使用基于梯度的形状优化来共同优化这些参数，并充分考虑结构之间的近场相互作用。我们将我们的概念应用于支持高衍射效率和偏振控制的各种元光栅，并且我们通过实验证明了一种具有作为波长函数的定制偏振响应的设备。通过我们的方法实现的设备功能、特征尺寸限制和易于制造性的结合将促进稳健、高性能、