Three-dimensional elements, with refractive index distribution structured at subwavelength scale, provide an expansive optical design space that can be harnessed for demonstrating multifunctional free-space optical devices. Here we present 3D dielectric elements, designed to be placed on top of the pixels of image sensors, that sort and focus light based on its color and polarization with efficiency significantly surpassing 2D absorptive and diffractive filters. The devices are designed via iterative gradient-based optimization to account for multiple target functions while ensuring compatibility with existing nanofabrication processes, and they are experimentally validated using a scaled device that operates at microwave frequencies. This approach combines arbitrary functions into a single compact element, even where there is no known equivalent in bulk optics, enabling novel integrated photonic applications.

中文翻译：

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用于彩色和偏振图像传感器的多功能体积亚光学

具有在亚波长尺度下构造的折射率分布的三维元素提供了广阔的光学设计空间，可以利用它来演示多功能自由空间光学设备。在这里，我们介绍3D介电元件，该元件设计成放置在图像传感器的像素上方，可根据其颜色和偏振对光进行分类和聚焦，其效率大大超过2D吸收和衍射滤光片。这些设备是通过基于迭代梯度的优化设计的，目的是在确保与现有纳米加工工艺兼容的同时考虑多种目标功能，并且使用在微波频率下运行的定标设备进行了实验验证。这种方法将任意功能组合到单个紧凑元素中，