The manipulation of polarization states beyond the optical limit presents advantages in various applications. Considerable progress has been made in the design of meta-waveplates for on-demand polarization transformation, realized by numerical simulations and parameter sweep methodologies. However, due to the limited freedom in these classical strategies, particular challenges arise from the emerging requirement for multiplex optical devices and multidimensional manipulation of light, which urge for a large number of different nanostructures with great polarization control capability. Here, we demonstrate a set of self-designed arbitrary wave plates with a high polarization conversion efficiency. We combine Bayesian optimization and deep neural networks to design perfect half- and quarter-waveplates based on metallic nanostructures, which experimentally demonstrate excellent polarization control functionalities with the conversion ratios of 85% and 90%. More broadly, we develop a comprehensive wave plate database consisting of various metallic nanostructures with high polarization conversion efficiency, accompanying a flexible tuning of phase shifts (0–2π$0–2\pi$) and group delays (0–10 fs), and construct an achromatic metalens based on this database. Owing to the versatility and excellent performance, our self-designed wave plates can promote the performance of multiplexed broadband metasurfaces and find potential applications in compact optical devices and polarization division multiplexing optical communications.

中文翻译：

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通过深度神经网络自行设计任意偏振控制波片

超出光学极限的偏振态操作在各种应用中具有优势。通过数值模拟和参数扫描方法实现按需偏振变换的元波片设计取得了相当大的进展。然而，由于这些经典策略的自由度有限，对多重光学器件和光的多维操纵的新兴需求带来了特殊的挑战，这需要大量具有强大偏振控制能力的不同纳米结构。在这里，我们展示了一组自行设计的具有高偏振转换效率的任意波片。我们结合贝叶斯优化和深度神经网络来设计基于金属纳米结构的完美的二分之一和四分之一波片，它通过实验证明了出色的偏振控制功能，转换率为 85% 和 90%。更广泛地说，我们开发了一个综合波片数据库，由具有高偏振转换效率的各种金属纳米结构组成，并伴随着灵活的相移调整（0 – 2 π$0–2\pi$ ) 和群时延 (0–10 fs)，并基于该数据库构建消色差超透镜。由于多功能性和优异的性能，我们自行设计的波片可以提升多路复用宽带超表面的性能，并在紧凑型光学器件和偏振分复用光通信中找到潜在的应用。