Zhang Zhaoxia, Li Zhangyin, Lei Jian, Wu Jin, Zhang Kun, Wang Sicong, Cao Yaoyu, Qin Fei, Li Xiangping
Opt Lett. 2021 May 15;46(10):2296-2299. doi: 10.1364/OL.425361.
Planar metalenses provide an effective way to break the diffraction barrier in the far field. Their physical mechanism and applications have been intensively studied in the past decade. These investigations on sub-diffraction-limited light modulations have only been applied to specified single immersion environments; however, changing immersion environments can severely degrade their focusing performance, limiting their application potential. In this work, we propose and experimentally demonstrate an environmentally robust immersion supercritical lens (SCL) that can work in various immersion environments. The design of such a lens is based on the vectorial Rayleigh-Sommerfeld diffraction theory combined with a multi-objective optimization algorithm. The sub-diffraction-limited focusing effect has been experimentally demonstrated in commonly used media, including air, water, and oil, with refractive indices of 1.0, 1.33, and 1.51, respectively. Moreover, such a lens can maintain its effective numerical aperture at a fixed value, bringing a unique advantage in that the lateral size of the focal spots exhibits a similar value of ${{317}};{{\pm}};{{7}};{\rm{nm}}$ in all three media. Our demonstration provides the feasibility of SCLs in various application scenarios with multi-immersion environments, such as bioimaging, light trapping, and optical storage.
平面超构透镜为突破远场衍射极限提供了一种有效方法。在过去十年中，人们对其物理机制和应用进行了深入研究。然而，这些关于亚衍射极限光调制的研究仅适用于特定的单一浸没环境；改变浸没环境会严重降低其聚焦性能，限制其应用潜力。在这项工作中，我们提出并通过实验证明了一种环境适应性强的浸没式超临界透镜（SCL），它可以在各种浸没环境中工作。这种透镜的设计基于矢量瑞利 - 索末菲衍射理论，并结合了多目标优化算法。我们已经在常用介质中通过实验证明了亚衍射极限聚焦效应，这些介质包括空气、水和油，其折射率分别为1.0、1.33和1.51。此外，这种透镜可以将其有效数值孔径保持在一个固定值，这带来了一个独特的优势，即在所有三种介质中，焦点的横向尺寸都呈现出相似的值，为${{317}};{{\pm}};{{7}};{\rm{nm}}$。我们的演示证明了SCL在多浸没环境的各种应用场景中的可行性，如生物成像、光捕获和光存储。
