Design of efficient broadband extreme ultraviolet multilayer mirrors using a two-parametric merit function
Design of efficient broadband extreme ultraviolet multilayer mirrors using a two-parametric merit function
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使用二参数评价函数设计高效宽带极紫外多层镜
DOI：
10.1016/j.optcom.2021.127018
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发表时间：
2021
影响因子：
2.4
通讯作者：
Lin Chengyou
中科院分区：
文献类型：
--
作者：
Lin Zhining;Bai Gaiyan;Chen Shujing;Lin Chengyou
宽带反射是极紫外（EUV）光学的基本要求，特别是对于诸如阿秒脉冲这样的宽带光源的控制。提出了一种基于遗传算法的宽带EUV多层膜反射镜设计方法。传统的评价函数一般采用计算反射率与目标反射率的均方根偏差作为评价函数，而本文提出的由反射率均值和均方根偏差组成的双参数评价函数，在不预先设定目标反射率的情况下，可以实现期望波段内较高的反射率均值和较低的反射率均方根偏差。利用该双参数评价函数，通过优化非周期Mo/Si多层膜，在60 ~ 80 eV波长范围内实现了平均反射率为20.35%，均方差为0.5%的宽带EUV反射镜。此外，设计了不同波段的宽带EUV反射镜，并对它们的宽带反射性能进行了分析和比较。该研究为设计一种高效的宽带吸收多层膜提供了一种思路，对宽带极紫外光源的控制研究具有一定的推动作用。
Broadband reflection is a basic need in extreme ultraviolet (EUV) optics, especially for the control of a broadband source such as attosecond pulse. In this paper, we propose a design method of broadband EUV multilayer mirrors based on genetic algorithm with a two-parametric merit function. Compared with a traditional merit function, which generally employs the root-mean-square deviation of the calculated reflectivity from the target reflectivity, the proposed two-parametric merit function consisting of mean value and mean square deviation of the reflectivity can realize higher mean value and lower mean square deviation of reflectivity in the desired band, without setting the target reflectivity in advance. Using this two-parametric merit function, a broadband EUV mirror with 20.35% mean value and 0.5% mean square deviation of reflectivity is realized in the wavelength range from 60 eV to 80 eV by optimizing an aperiodic Mo/Si multilayer. In addition, the broadband EUV mirrors for different bands are designed, and their performances of broadband reflection are analyzed and compared. Our research provides a way of designing an efficient broadband multilayer with absorbing materials, and could improve the study on the control of broadband EUV sources.