Impact of fabrication errors and refractive index on multilevel diffractive lens performance
Impact of fabrication errors and refractive index on multilevel diffractive lens performance
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DOI：
10.1038/s41598-020-71480-2
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发表时间：
2020-09-03
影响因子：
4.6
通讯作者：
Sensale-Rodriguez, Berardi
中科院分区：
文献类型：
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作者：
Banerji, Sourangsu;Cooke, Jacqueline;Sensale-Rodriguez, Berardi
多层衍射透镜（mdl）已经成为传统衍射光学元件（do）和超透镜的替代品，应用范围从成像到全息和沉浸式显示。最近的研究表明，通过利用do的结构参数优化，可以设计mdl，使其具有消色度、聚焦深度、广角成像等多种功能，并且易于制造。因此，了解制造误差如何仍然影响MDL的性能并在设计MDL开始时（即甚至在将其投入制造之前）对效率和初始参数选择之间的权衡进行数值评估变得至关重要。在这里，我们对mdl（主要在太赫兹范围内工作）进行了基于统计模拟的研究，以分析各种制造缺陷（单个和多个）对最终结构的影响，作为环高度水平数量的函数。此外，我们还通过本构材料折射率的变化来评估这些相同的mdl的性能。在数值分析中，我们以聚焦效率作为评价标准；因为它是最基本的属性，可以用来比较和评估镜头（和mdl）的性能，一般设计用于任何特定功能的任何应用。
Multilevel diffractive lenses (MDLs) have emerged as an alternative to both conventional diffractive optical elements (DOEs) and metalenses for applications ranging from imaging to holographic and immersive displays. Recent work has shown that by harnessing structural parametric optimization of DOEs, one can design MDLs to enable multiple functionalities like achromaticity, depth of focus, wide-angle imaging, etc. with great ease in fabrication. Therefore, it becomes critical to understand how fabrication errors still do affect the performance of MDLs and numerically evaluate the trade-off between efficiency and initial parameter selection, right at the onset of designing an MDL, i.e., even before putting it into fabrication. Here, we perform a statistical simulation-based study on MDLs (primarily operating in the THz regime) to analyse the impact of various fabrication imperfections (single and multiple) on the final structure as a function of the number of ring height levels. Furthermore, we also evaluate the performance of these same MDLs with the change in the refractive index of the constitutive material. We use focusing efficiency as the evaluation criterion in our numerical analysis; since it is the most fundamental property that can be used to compare and assess the performance of lenses (and MDLs) in general designed for any application with any specific functionality.