Integrating conventional optics into compact nanostructured surfaces is the goal of flat optics. Despite the enormous progress in this technology, there are still critical challenges for real-world applications due to the limited operational efficiency in the visible region, on average lower than 60%, which originates from absorption losses in wavelength-thick (≈ 500 nm) structures. Another issue is the realization of on-demand optical components for controlling vectorial light at visible frequencies simultaneously in both reflection and transmission and with a predetermined wavefront shape. In this work, we developed an inverse design approach that allows the realization of highly efficient (up to 99%) ultrathin (down to 50 nm thick) optics for vectorial light control with broadband input–output responses in the visible and near-IR regions with a desired wavefront shape. The approach leverages suitably engineered semiconductor nanostructures, which behave as a neural network that can approximate a user-defined input–output function. Near-unity performance results from the ultrathin nature of these surfaces, which reduces absorption losses to near-negligible values. Experimentally, we discuss polarizing beam splitters, comparing their performance with the best results obtained from both direct and inverse design techniques, and new flat-optics components represented by dichroic mirrors and the basic unit of a flat-optics display that creates full colours by using only two subpixels, overcoming the limitations of conventional LCD/OLED technologies that require three subpixels for each composite colour. Our devices can be manufactured with a complementary metal-oxide-semiconductor (CMOS)-compatible process, making them scalable for mass production at low cost.

将常规光学器件集成到紧凑的纳米结构表面中是平面光学器件的目标。尽管这项技术取得了巨大进步，但是由于可见光区域的工作效率有限（平均低于60％），这对现实世界的应用仍然存在着严峻的挑战，这是由于波长范围内（约500 nm）的吸收损耗所致结构。另一个问题是实现按需的光学部件，该按需的光学部件以反射和透射的方式并以预定的波前形状同时控制可见光频率的矢量光。在这项工作中，我们开发了一种逆向设计方法，该方法可实现用于矢量光控制的高效（高达99％）超薄（厚度小于50 nm）光学器件，并在可见光和近红外区域具有所需波前的宽带输入-输出响应形状。该方法利用经过适当设计的半导体纳米结构，该结构充当可以近似用户定义的输入-输出功能的神经网络。这些表面的超薄特性使它们具有近乎统一的性能，从而将吸收损耗降低到几乎可以忽略不计的值。通过实验，我们讨论了偏振分束器，将其性能与直接和反向设计技术获得的最佳结果进行了比较，以及以二向色镜为代表的新型平板光学组件以及仅使用两个子像素即可产生全彩色的平板光学显示器的基本单元，从而克服了传统LCD / OLED技术的局限，每种复合颜色需要三个子像素。我们的设备可以采用互补的金属氧化物半导体（CMOS）兼容工艺制造，从而使其可扩展以低成本进行大规模生产。