Metasurfaces have recently emerged to realize flat optical components with various functions and providing potential capabilities in manufacturing active devices. In this paper, a doublet lens for mid-infrared wavelength with tunable focal length has been proposed. The designed metalens consists of two dielectric metalenses with different focal lengths patterned on a phase-change materials Ge2Sb1Te4. The doublet lens is proved to have above 13% change in the focal length with the crystalline states shifting of the Ge2Sb1Te4. And the designed doublet lens can be operated in mid-infrared region from 2.41 [Formula: see text]m to 2.60 [Formula: see text]m. In addition, chromatic calibration can be achieved by adjusting the crystalline phases of the Ge2Sb1Te4. This compatible metalens promises potential for a wide range of applications in MIR region such as multi-spectrum imaging, optical coupling system and micrography.

中文翻译：

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使用相变材料的基于介电超表面的可调谐双合透镜

最近出现了超表面来实现具有各种功能的平面光学元件，并为制造有源器件提供了潜在的能力。本文提出了一种焦距可调的中红外波长双合透镜。设计的元透镜由两个具有不同焦距的介电元透镜组成，在相变材料 Ge 上图案化2锑1碲4. 事实证明，双合透镜的焦距变化超过 13%，Ge 的晶态转移2锑1碲4. 并且所设计的双合透镜可以在2.41[公式：见正文]m到2.60[公式：见正文]m的中红外区域工作。此外，可以通过调整 Ge 的晶相来实现色度校准2锑1碲4. 这种兼容的超透镜有望在中红外区域广泛应用，例如多光谱成像、光学耦合系统和显微摄影。