Liu Chang, Wu Tiesheng, Liu Yumin, Li Jing, Wang Yu, Yu Zhongyuan, Ye Han, Yu Li
Opt Express. 2019 Feb 18;27(4):5703-5718. doi: 10.1364/OE.27.005703.
Perfect absorbers play crucial roles in optical functional devices. Among various types of absorbers, moth-eye structures are known for their excellent absorbing efficiency. In this paper, we apply an electromagnetic multipole expansion method to treat an isolated all-dielectric moth-eye structure as a large particle and calculate various electric and magnetic multipole modes within the moth-eye structure. In periodical array, the multipole modes within each particle interact with each other. These constructive or destructive interactions cause shifts in the multipole resonant peaks. The multipole modes inside the particle array introduce reflecting peaks for loss-less materials. The absorption enhancement inside moth-eye structures can be attributed to the electric field enhancement resulting from these electric and magnetic multipole modes. Based on our theoretical study, we propose a near-ideal selective absorber based on moth-eye array, which achieves near 100% absorption within wavelength range from 400 nm to 1500 nm while achieving near 0% absorption over about 1700 nm.
完美吸收体在光学功能器件中起着至关重要的作用。在各种类型的吸收体中，蛾眼结构以其优异的吸收效率而闻名。在本文中，我们应用电磁多极展开方法将孤立的全介质蛾眼结构视为一个大粒子，并计算蛾眼结构内的各种电多极和磁多极模式。在周期性阵列中，每个粒子内的多极模式相互作用。这些相长或相消的相互作用会导致多极共振峰发生偏移。粒子阵列内部的多极模式会为无损耗材料引入反射峰。蛾眼结构内部的吸收增强可归因于这些电多极和磁多极模式所导致的电场增强。基于我们的理论研究，我们提出了一种基于蛾眼阵列的近理想选择性吸收体，它在400纳米至1500纳米的波长范围内实现了近100%的吸收，而在约1700纳米以上的波长范围内实现了近0%的吸收。
