Martins Augusto, Li Juntao, Borges Ben-Hur V, Krauss Thomas F, Martins Emiliano R
São Carlos School of Engineering, Department of Electrical and Computer Engineering, University of São Paulo, São Carlos 13566-590, Brazil.
State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China.
Nanophotonics. 2022 Feb 16;11(6):1187-1194. doi: 10.1515/nanoph-2021-0770. eCollection 2022 Feb.
Metalenses are nanostructured surfaces with great potential for delivering miniaturized and integrated optical systems. A key property of metalenses is that, by using a double layer configuration, or doublet, they can achieve both diffraction-limited resolution and wide field-of-view imaging. The physical operation and limitations of such doublet systems, however, are still not fully understood, and designs are still based on numerical optimization of the phase profiles. Here, we show the fundamental limits of doublet systems and provide a universal design strategy without any need to resort to numerical optimization. We find an analytical relationship between the focal length and the spacer thickness; we identify the physical principles underlying the limitations on performance and obtain a universal dependence of the field of view as a function of resolution (numerical aperture). Our results will allow researchers to appreciate the regimes of resolution and field of view that are accessible for specific applications, to identify the conditions for optimum performance (such as required spacer thickness), and to conveniently design doublets without needing to resort to numerical optimizations.
超颖透镜是具有纳米结构的表面，在实现小型化和集成光学系统方面具有巨大潜力。超颖透镜的一个关键特性是，通过使用双层结构（即双合透镜），它们可以实现衍射极限分辨率和宽视场成像。然而，这种双合透镜系统的物理运作和局限性仍未得到充分理解，其设计仍基于相位分布的数值优化。在此，我们展示了双合透镜系统的基本极限，并提供了一种无需进行数值优化的通用设计策略。我们发现了焦距与间隔层厚度之间的解析关系；我们确定了性能受限的物理原理，并得出视场作为分辨率（数值孔径）函数的通用依赖关系。我们的结果将使研究人员能够了解特定应用可达到的分辨率和视场范围，确定最佳性能的条件（如所需的间隔层厚度），并方便地设计双合透镜，而无需进行数值优化。
