论文标题
专注于带宽：具有色的金属限制
Focusing on Bandwidth: Achromatic Metalens Limits
论文作者
论文摘要
金属镜在其功能充当聚焦和成像的超型光学系统的能力方面表现出了巨大的希望。值得注意的是，最近已经证明了几种设计，这些设计在各种频率上运行，并具有最小的色差畸变，这可能为超薄纯粹的骨质光学元件铺平了道路。在这里，我们得出了适用于宽带光学金属的基本带宽限制，无论其实施如何。具体而言，我们讨论了可实现的时间延迟和带宽之间的产品在任何时间不变的系统中如何受到限制，并且我们将该产品上的完善界限应用于一般的聚焦系统。然后，我们证明迄今为止设计的所有金属均遵守适当的带宽极限。派生的物理界限提供了一个有用的指标，可以比较和评估不同设备的性能，并为如何设计更好的宽带金属镜提供了基本的见解。
Metalenses have shown great promise in their ability to function as ultracompact optical systems for focusing and imaging. Remarkably, several designs have been recently demonstrated that operate over a large range of frequencies with minimized chromatic aberrations, potentially paving the way for ultrathin achromatic optics. Here, we derive fundamental bandwidth limits that apply to broadband optical metalenses, regardless of their implementation. Specifically, we discuss how the product between achievable time delay and bandwidth is limited in any time-invariant system, and we apply well-established bounds on this product to a general focusing system. We then show that all metalenses designed thus far obey the appropriate bandwidth limit. The derived physical bounds provide a useful metric to compare and assess the performance of different devices, and offer fundamental insight into how to design better broadband metalenses.
