Lio Giuseppe Emanuele, Palermo Giovanna, Caputo Roberto, De Luca Antonio
CNR-Nanotec, Cosenza and Physics Department, University of Calabria 87036 Arcavacata di Rende CS Italy
RSC Adv. 2019 Jul 11;9(37):21429-21437. doi: 10.1039/c9ra03684a. eCollection 2019 Jul 5.
A simple and robust method able to evaluate and predict, with high accuracy, the optical properties of single and multi-layer nanostructures is presented. The method was implemented using a COMSOL Multiphysics simulation platform and it has been validated by four case studies with increasing numerical complexities: (i) a single thin layer (20 nm) of Ag deposited on a glass substrate; (ii) a metamaterial composed of five bi-layers of Ag/ITO (indium tin oxide), with a thickness of 20 nm each; (iii) a system based on a three-material unit cell (AZO/ITO/Ag), but without any thickness periodicity (AZO stands for AlO/zinc oxide); (iv) an asymmetric nanocavity (thin-ITO/Ag/thick-ITO/Ag). A thorough study of this latter configuration reveals peculiar metamaterial effects that can widen the actual scenario in nanophotonic applications. Numerical results have been compared with experimental data provided by real ellipsometric measurements performed on the above mentioned fabricated nanostructures. The obtained agreement is excellent, suggesting this research as a valid design approach to realize multi-band metamaterials able to work in a broad spectral range.
本文提出了一种简单且稳健的方法，该方法能够高精度地评估和预测单层及多层纳米结构的光学特性。该方法是使用COMSOL Multiphysics模拟平台实现的，并通过四个数值复杂度不断增加的案例研究进行了验证：（i）沉积在玻璃基板上的单层20 nm厚的Ag薄膜；（ii）由五个双层Ag/ITO（氧化铟锡）组成的超材料，每个双层厚度为20 nm；（iii）基于三材料单元胞（AZO/ITO/Ag）的系统，但没有任何厚度周期性（AZO代表AlO/氧化锌）；（iv）一个不对称纳米腔（薄ITO/Ag/厚ITO/Ag）。对后一种结构的深入研究揭示了特殊的超材料效应，这可以拓宽纳米光子学应用中的实际场景。数值结果已与对上述制造的纳米结构进行实际椭偏测量所提供的实验数据进行了比较。所获得的一致性非常好，表明这项研究是一种有效的设计方法，可用于实现能够在宽光谱范围内工作的多波段超材料。
