Imaging Performance of Polarization-Insensitive Metalenses
Imaging Performance of Polarization-Insensitive Metalenses
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DOI：
10.1021/acsphotonics.9b00221
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发表时间：
2019-06-01
期刊：
影响因子：
7
通讯作者：
Petschulat, Joerg
中科院分区：
文献类型：
--
作者：
Decker, Manuel;Chen, Wei Ting;Petschulat, Joerg
超表面最近成为一种有前途的技术，可实现具有定制功能的平面光学元件。特别是，它们在各种成像系统中的镜头中的应用引起了人们的极大兴趣。然而，目前尚未对超透镜的聚焦和成像行为进行系统、完整的研究。在这项工作中，我们不仅分析了轴上聚焦性能，还通过相位检索优化方法分析了场相关的波前像差。我们发现，特别是对于高数值孔径的超透镜，在设计波长处，场相关的几何像差（如慧差）占主导地位，而对于较长和较短的工作波长，有效数值孔径会降低，并且主要是球面像差占主导地位。此外，我们通过分析超透镜效率作为数值孔径、视场角和波长的函数来研究偏振不敏感超透镜的光谱和角带宽。然后，我们将超透镜性能与其折射和衍射对应物进行比较，并展示各自的超透镜特性如何影响成像性能。为此，我们根据这三种情况的场和波长相关的绝对偏转效率进行成像模拟，并分析扩展测试对象的成像特性。我们的计算表明，超透镜在大偏转角的角度相关效率方面优于衍射透镜。
Metasurfaces have recently emerged as a promising technology to realize flat optical components with customized functionalities. In particular, their application to lenses in various imaging systems is of significant interest. However, a systematic and complete study of the focusing and imaging behavior of metalenses has not yet been conducted. In this work we analyze not only the on-axis focusing performance, but also the field-dependent wavefront aberrations via a phase-retrieval optimization method. We find that, particularly for high-NA metalenses, the field-dependent geometrical aberrations like coma are dominant at the design wavelength, while for longer and shorter operation wave- lengths, the effective numerical aperture is decreased and mainly spherical aberrations are dominant. Additionally, we investigate the spectral and angular bandwidth of a polarization-insensitive metalens by analyzing the metalens efficiencies as a function of numerical aperture, field angle, and wavelength. We then compare the metalens performance to its refractive and diffractive counterparts and show how the respective metalens properties affect the imaging performance. For this purpose, we perform an imaging simulation for these three cases based on their field- and wavelength-dependent absolute deflection efficiencies and analyze the imaging properties of an extended test object. Our calculations show that metalenses can outperform diffractive lenses in terms of their angle-dependent efficiency for large deflection angles.